Network Working Group               G. Sidebottom, L. Ong,                          Greg Sidebottom (Editor)
INTERNET-DRAFT                                             Guy Mousseau
INTERNET-DRAFT
                                                        Nortel Networks
                                                             Lyndon Ong
                                                   Point Reyes Networks
                                                             Ian Rytina
                                                               Ericsson
                                             Hanns-Juergen Schwarzbauer, Schwarzbauer
                                                      Klaus Gradischnig
                                                                Siemens
                                                          Ken Morneault
                                                                  Cisco
                                                          Mallesh Kalla
                                                              Telcordia
                                                         Normand Glaude
                                               Performance Technologies

Expires in six months                                         Nov 2000                                         Feb 2001

                SS7 MTP3-User Adaptation Layer (M3UA)
                  <draft-ietf-sigtran-m3ua-05.txt>
                  <draft-ietf-sigtran-m3ua-06.txt>

Status of This Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC 2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, and
its working groups.  Note that other groups may also distribute working
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Abstract

This Internet Draft defines a protocol for supporting the transport of
any SS7 MTP3-User signalling (e.g., ISUP and SCCP messages) over IP
using the services of the Stream Control Transmission Protocol.  Also,
provision is made for protocol elements that enable a seamless
operation of the MTP3-User peers in the SS7 and IP domains. This

protocol would be used between a Signalling Gateway (SG) and a Media
Gateway Controller (MGC) or IP-resident Database.  It is assumed that
the SG receives SS7 signalling over a standard SS7 interface using the
SS7 Message Transfer Part (MTP) to provide transport.

                        TABLE OF CONTENTS

1. Introduction.......................................................3 Introduction.......................................................4
    1.1 Scope.........................................................3 Scope.........................................................4
    1.2 Terminology...................................................3 Terminology...................................................4
    1.3 M3UA Overview.................................................5 Overview.................................................6
    1.4 Functional Areas.............................................10 Areas.............................................12
    1.5 Sample Configurations........................................18 Configurations........................................23
    1.6 Definition of M3UA Boundaries................................21 Boundaries................................26
2. Conventions.......................................................22 Conventions.......................................................29
3. M3UA Protocol Elements............................................22 Elements............................................29
    3.1 Common Message Header........................................22 Header........................................29
    3.2 Variable-Length Parameter Format Parameter....................................32
    3.3 Transfer Messages............................................24 Messages............................................33
    3.4 SS7 Signalling Network management (SSNM) Messages............26 Messages............36
    3.5 Application Server Process Maintenance Messages..............32 (ASPM) Messages.......44
    3.6 Management Messages..........................................40 Messages..........................................60
4. Procedures........................................................44 Procedures........................................................63
    4.1 Procedures to Support the Services of the M3UA Layer.........44 Layer.........63
    4.2 Procedures to Support the Receipt of M3UA Services in Section 1.4.2.....44 Peer Management Messages.....................65
    4.3 Procedures to Support support the M3UA Services in Section 1.4.4.....45 Management services...........66
    4.4 Procedures to Support the M3UA Services in Section 1.4.3.....52 Services......................78
5. Examples of M3UA Procedures.......................................54 Procedures.......................................81
    5.1 Establishment of Association and Traffic
        Between SGs and ASPs.........................................54 ASPs.........................................81
    5.2 ASP traffic Fail-over Examples...............................56 Examples...............................86
    5.3 M3UA/MTP3-User Boundary Examples.............................57 Examples.............................87
6. Security..........................................................61 Security..........................................................91
    6.1 Introduction.................................................61 Introduction.................................................91
    6.2 Threats......................................................61 Threats......................................................91
    6.3 Protecting Confidentiality...................................62 Confidentiality...................................91
7. IANA Considerations...............................................62 Considerations...............................................92
    7.1 SCTP Payload Protocol Identifier.............................62 Identifier.............................92
    7.2 M3UA Protocol Extensions.....................................62 Extensions.....................................92
8. Acknowledgements..................................................62 Acknowledgements..................................................93
9. References........................................................62 References........................................................93
10. Author's Addresses...............................................65 Addresses...............................................95

1.  Introduction

1.1 Scope

There is a need for SCN Switched Circuit Network (SCN) signalling protocol
delivery from an SS7 Signalling Gateway (SG) to a Media Gateway
Controller (MGC) or IP-
resident IP-resident Database as described in the Framework
Architecture for Signalling Transport [1].  The delivery mechanism should
SHOULD meet the following criteria:

*  Support for the transfer of all SS7 MTP3-User Part messages (e.g.,
   ISUP, SCCP, TUP, etc.)
*  Support for the seamless operation of MTP3-User protocol peers
*  Support for the management of SCTP transport associations and
   traffic between an SG and one or more MGCs or IP-resident Databases
*  Support for MGC or IP-resident Database process fail-over and load-
   sharing
*  Support for the asynchronous reporting of status changes to
   management

In simplistic transport terms, the SG will terminate SS7 MTP2 and MTP3
protocol layers and deliver ISUP, SCCP and/or any other MTP3-User
protocol messages messages, as well as certain MTP network management events,
over SCTP transport associations to MTP3-User peers in MGCs or IP-resident IP-
resident Databases.

1.2 Terminology

Application Server (AS) - A logical entity serving a specific Routing
Key. An example of an Application Server is a virtual switch element
handling all call processing for a unique range of PSTN trunks,
identified by an SS7 DPC/OPC/CIC_range.  Another example is a virtual
database element, handling all HLR transactions for a particular SS7
DPC/OPC/SCCP_SSN combination.  The AS contains a set of one or more
unique Application Server Processes, of which one or more is normally
actively processing traffic.

Application Server Process (ASP) - A process instance of an Application
Server. An Application Server Process serves as an active or standby
process of an Application Server (e.g., part of a distributed virtual
switch or database). Examples of ASPs are processes (or process
instances) of MGCs, IP SCPs or IP HLRs.  An ASP contains an SCTP end-
point and may be configured to process signalling traffic within more
than one Application Server.

Association - An association refers to an SCTP association.  The
association provides the transport for the delivery of MTP3-User
protocol data units and M3UA adaptation layer peer messages.

IP Server Process (IPSP) - A process instance of an IP-based
application.  An IPSP is essentially the same as an ASP, except that it
uses MU3A M3UA in a peer-to-peer point-to-point fashion.  Conceptually, an IPSP does not
use the services of a signalling gateway. Signalling Gateway.

Signalling Gateway Process (SGP) - A process instance of a Signalling
Gateway.  It serves as an active, standby or load-sharing process of a
Signalling Gateway.

Signalling Process - A process instance that uses M3UA to communicate
with other signalling process.  An ASP, a signalling gateway process
and an IPSP are all signalling processes.

Routing Key: A Routing Key describes a set of SS7 parameter parameters and
parameter values that uniquely define the range of signalling traffic
to be handled by a particular Application Server. For example, where
all traffic directed to an SS7 DPC, OPC and ISUP CIC_range(s) or SCCP
SSN is to be sent to a particular Application Server, that SS7 data
defines the associated Routing Key.  Routing Keys are unique in Parameters within the
sense that a received SS7 signalling message cannot be directed to more
than one Routing Key.   Also, a
Routing Key cannot extend across more than a single SS7 DPC, in order to more easily support SS7 Management
procedures.  It is not necessary for the parameter range values within
a particular Destination
Point Code.

Routing Key to be contiguous.  For example, an ASP could
be configured to support call processing for multiple ranges of PSTN
trunks Context - A value that are not represented by contiguous CIC values. uniquely identifies a Routing Key.
Routing Context - An Application Server Process may be values are either configured using a configuration
management interface, or by using the routing key management procedures
defined in this document.

Fail-over - The capability to
process re-route signalling traffic related as required
to more than one Application Server,
over a single SCTP Association.  At an ASP, the Routing Context
parameter uniquely identifies the range alternate Application Server Process, or group of signalling traffic
associated with each ASPs, within an
Application Server that the ASP is configured to
receive.  There is a 1:1 relationship between a received Routing
Context value and a Routing Key entry at the sending node.  Therefore
the Routing Context can be viewed as an index into a sending node's
Message Distribution Table containing the Routing Key entries.

Fail-over - The capability to re-route signalling traffic as required
to an alternate Application Server Process, or group of ASPs, within an
Application Server in in the event of failure or unavailability of a
currently used Application Server Process.  Fail-back may apply  Fail-over also applies upon
the return to service of a previously unavailable Application Server
Process.

Signalling Point Management Cluster (SPMC) - The complete set of
Application Servers represented to the SS7 network under one specific
SS7 Point Code of one specific Network Appearance.  SPMCs are used to
sum the availability / congestion / User_Part status of an SS7
destination point code that is distributed in the IP domain, for the
purpose of supporting MTP3 management procedures at an SG.  In some
cases, the SG itself may also be a member of the SPMC.  In this case,
the SG availability / congestion / User_Part status must also be taken
into account when considering any supporting MTP3 management actions.

MTP - The Message Transfer Part of the SS7 protocol.

MTP3 - MTP Level 3, the signalling network layer of SS7

MTP3-User - Any protocol normally using the services of the SS7 MTP3
(e.g., ISUP, SCCP, TUP, etc.).

Network Appearance - The Network Appearance identifies an SS7 network
context for the purposes of logically separating the signalling traffic

between the SG and the Application Server Processes over a common SCTP
Association.  An example is where an SG is logically partitioned to
appear as an element in four separate national SS7 networks.  A Network
Appearance implicitly defines the SS7 Point Code(s), Network Indicator
and MTP3 protocol type/variant/version used within a specific SS7
network partition.  A physical SS7 route-set or link-set at an SG can
appear in only one network appearance. The Network Appearance is not
globally significant and requires coordination only between the SG and
the ASP. Therefore, in the case where an ASP is connected to more than
one SG, the same SS7 network context may be identified by different
Network Appearances depending over which SG a message is being
transmitted/received.

Network Byte Order: Most significant byte first, a.k.a Big Endian.

Layer Management - Layer Management is a nodal function that handles
the inputs and outputs between the M3UA layer and a local management
entity.

Host - The computing platform that the ASP process is running on.

Stream - A stream refers to an SCTP stream; a uni-directional logical
channel established from one SCTP endpoint to another associated SCTP
endpoint, within which all user messages are delivered in-sequence
except for those submitted to the un-ordered delivery service.

1.3 M3UA Overview

1.3.1 Protocol Architecture.

The framework architecture that has been defined for SCN signalling
transport over IP [1] uses multiple components, including a common
signalling transport protocol and an adaptation module to support the
services expected by a particular SCN signalling protocol from its
underlying protocol layer.

Within the framework architecture, this document defines an MTP3-User
adaptation module suitable for supporting the transfer of messages of
any protocol layer that is identified to the MTP Level 3 layer, in SS7
terms, as a user part.  The list of these protocol layers include, but
is not limited to, ISDN User Part (ISUP) [2,3,4], Signalling Connection
Control Part (SCCP) [5,6,7] and Telephone User Part (TUP) [8].  TCAP
[9,10,11] or RANAP [12] messages are transferred transparently by the
M3UA as SCCP payload, as they are SCCP-User protocols.

It is recommended that the M3UA use the services of the Stream Control
Transmission Protocol (SCTP) [13] as the underlying reliable common
signalling transport protocol. This is to take advantage of various
SCTP features such as:

   - Explicit packet-oriented delivery (not stream-oriented);
   - Sequenced delivery of user messages within multiple streams,
     with an option for order-of-arrival delivery of individual
     user messages,
   - Optional multiplexing of user messages into SCTP datagrams;
   - Network-level fault tolerance through support of multi-homing
     at either or both ends of an association;
   - Resistance to flooding and masquerade attacks; and
   - Data segmentation to conform to discovered path MTU size.

Under certain scenarios, such as back-to-back connections without
redundancy requirements, the SCTP functions above may not MAY NOT be necessary.
In these cases, it is acceptable to use a
requirement and TCP can be used as the underlying common transport
protocol.

1.3.2 Services Provided by the M3UA Layer

The M3UA Layer at an ASP or IPSP provides the equivalent set of
primitives at its upper layer to the MTP3-Users as provided by the MTP
Level 3 to its local users MTP3-Users at an SS7 SEP.  In this way, the ISUP
and/or SCCP layer at an ASP or IPSP is unaware that the expected MTP3
services are offered remotely from an MTP3 Layer at an SG, and not by a
local MTP3 layer.  The MTP3 layer at an SG may also be unaware that its
local users are actually remote user parts over M3UA.  In effect, the
M3UA extends access to the MTP3 layer services to a remote IP-based
application.  The M3UA does not itself provide the MTP3 services.  In
However, in the case where an ASP is connected to more than one SG, however, the
M3UA Layer at an ASP must maintain the status of configured SS7
destinations and route messages according to
availability/congestion the availability /
congestion status of the routes to these destinations. destinations via each SG.

The M3UA Layer may also be used for point-to-point signalling between
two IP Server Processes (IPSPs).  In this case, the M3UA provides the
same set of primitives and services at its upper layer as the MTP3.
However, in this case the expected MTP3 services are not offered
remotely from an SG.  The MTP3 services are provided but the procedures
to support these services are a subset of the MTP3 procedures due to
the simplified point-to-point nature of the IPSP to IPSP relationship.

1.3.2.1 Support for the transport of MTP3-User Messages

The M3UA provides the transport of MTP-TRANSFER primitives across an
established SCTP association between an SG and an ASP or between IPSPs.

The MTP-TRANSFER primitive information is encoded as in MTP3-User
messages.  In this way, the SCCP and ISUP messages received from the
SS7 network by the SG are not re-encoded into a different format for
transport between the M3UA peers.  The MTP3 Service Information Octet
(SIO) and Routing Label (OPC, DPC, and SLS) are included, encoded as
expected by the MTP3 and MTP3-User protocol layer.

At an ASP, in the case where a destination is reachable via multiple
SGs, the M3UA must also choose via which SG the message is to be routed
or support load balancing across the SGs, ensuring that no mis-
sequencing occurs.

The M3UA does not impose a 272-octet user signaling information block field (SIF)
length limit as specified by the SS7 MTP Level 3 protocol. 2 protocol [14] [15]
[16].  Larger information blocks can be accommodated directly by
M3UA/SCTP, without the need for an upper layer segmentation/re-assembly
procedure as specified in recent SCCP or ISUP versions.  However, in
the context of an SG, the maximum 272-octet block size must be followed
when inter-working to a SS7 network that does not support the transfer
of larger information blocks to the final destination.  This avoids
potential ISUP or SCCP fragmentation requirements at the SG.  However,
if the SS7 network is provisioned to support the Broadband MTP [20] to
the final SS7 destination, the information block size limit may be
increased past 272 octets.

1.3.2.2 Native Management Functions

The M3UA provides management of the underlying SCTP transport protocol
to ensure that SG-ASP and IPSP-IPSP transport is available to the
degree called for by the MTP3-User signalling applications.

The M3UA provides the capability to indicate errors associated with
received M3UA messages and to notify, as appropriate, local management
and/or the peer M3UA.

1.3.2.3 Inter-working with MTP3 Network Management Functions

At the SG, the M3UA must also provide inter-working with MTP3
management functions to support seamless operation of the user SCN
signalling applications in the SS7 and IP domains.  This includes:

  - Providing an indication to MTP3-Users at an ASP that a remote
    destination in the SS7 network is not reachable.

  - Providing an indication to MTP3-Users at an ASP that a remote
    destination in the SS7 network is now reachable.

  - Providing an indication to MTP3-Users at an ASP that messages to a
    remote MTP3-User peer in the SS7 network are experiencing SS7
    congestion.

  - Providing an indication to MTP3-Users at an ASP that the routes to
    a remote MTP3-User peer in the SS7 network are restricted.

  - Providing an indication to MTP3-Users at an ASP that a remote MTP3-
    User peer is unavailable.

The M3UA layer at an ASP may initiate an audit of the availability availability, the
restricted or the congested state of remote SS7 destinations.  This
information is requested from the M3UA at the SG.

The M3UA layer at an ASP may also indicate to the SG that the M3UA
itself or the ASP or the ASP's host Host is congested.

1.3.2.4 Support for the management of SCTP associations between the SG
and ASPs.

The M3UA layer at the SG maintains the availability state of all
configured local and remote ASPs, in order to manage the SCTP Associations and
the traffic between the M3UA peers.  As well, the active/inactive and
congestion state of local and remote ASPs is also maintained.

The M3UA layer may MAY be instructed by local management to establish an
SCTP association to a peer M3UA node.  This can be achieved using the
M-SCTP ESTABLISH primitive to request, indicate and confirm the
establishment of an SCTP association with a peer M3UA node.  In order
to avoid redundant SCTP associations between two M3UA peers, one side
(client) must be designated to establish the SCTP association association, or M3UA
configuration knowledge maintained to detect redundant associations
(e.g., via knowledge of the mutual expected local and remote SCTP endpoint addresses must be pre-configured.
addresses).

The M3UA layer may MAY also need to inform local management of the status
of the underlying SCTP associations using the M-SCTP STATUS request and
indication primitive. For example, the M3UA may MAY inform local management
of the reason for the release of an SCTP association, determined either
locally within the M3UA layer or by a primitive from the SCTP.

Also the M3UA layer may need to inform the local management of the
change in status of an ASP or AS.  This may be achieved using the M-ASP
STATUS request or M-AS STATUS request primitives.

1.3.2.5 Support for the management of connections to multiple SGs

As shown in Figure 1 an ASP may be connected to multiple SGs. In such a
case a particular SS7 destination may be reachable via more than SG,
i.e., via more than one route. As MTP3 users only maintain status on a
destination and not on a route basis basis, M3UA must maintain the status
(availability
(availability, restriction, and/or congestion of route to destination)
of the individual routes, derive the overall availability or congestion
status of the destination from the status of the individual routes, and
inform the MTP3 users of this derived status whenever it changes.

1.3.3 Signalling Network Architecture

A Signalling Gateway is used to support the transport of MTP3-User
signalling traffic received from the SS7 network to multiple

distributed ASPs (e.g., MGCs and IP Databases).  Clearly, the M3UA
protocol is not designed to meet the performance and reliability
requirements for such transport by itself.  However, the conjunction of
distributed architecture and redundant networks does allow for a
sufficiently reliable transport of signalling traffic over IP.  The
M3UA protocol is flexible enough to allow its operation and management
in a variety of physical configurations, enabling Network Operators to
meet their performance and reliability requirements.

To meet the stringent SS7 signalling reliability and performance
requirements for carrier grade networks, Network Operators should SHOULD
ensure that no single point of failure is present in the end-to-end
network architecture between an SS7 node and an IP-based application.
This can typically be achieved through the use of redundant SGs,
redundant hosts, and the provision of redundant QOS-bounded IP network
paths for SCTP Associations between SCTP End Points. Obviously, the
reliability of the SG, the MGC and other IP-based functional elements
also needs to be taken into account.  The distribution of ASPs within
the available Hosts must also be considered.  As an example, for a
particular Application Server, the related ASPs should be distributed
over at least two Hosts.

One example of a physical network architecture relevant to SS7 carrier-
grade operation in the IP network domain is shown in Figure 1 below:

          SG                                     MGC

  Host#1 **************                          ************** Host#1
     =   *  ********__*__________________________*__********  *   =
    SG1  *  * SGP1 *__*_____      _______________*__* ASP1 *  *  MGC1
         *  ********  *     \    /               *  ********  *
         *  ********__*______\__/________________*__********  *
         *  * SGP2 *__*_______\/______      _____*__* ASP2 *  *
         *  ********  *       /\      |    |     *  ********  *
         *      :     *      /  \     |    |     *      :     *
         *  ********  *     /    \    |    |     *  ********  *
         *  * SGPn *  *     |    |    |    |     *  * ASPn *  *
         *  ********  *     |    |    |    |     *  ********  *
         **************     |    |    |    |     **************
                            |    |    \    /
  Host#2 **************     |    |     \  /      ************** Host#2
     =   *  ********__*_____|    |______\/_______*__********  *   =
    SG2  *  * SGP1 *__*_________________/\_______*__* ASP1 *  *  MGC2
         *  ********  *                /  \      *  ********  *
         *  ********__*_______________/    \_____*__********  *
         *  * SGP2 *__*__________________________*__* ASP2 *  *
         *  ********  *                          *  ********  *
         *      :     *     SCTP Associations    *      :     *
         *  ********  *                          *  ********  *
         *  * SGPn *  *                          *  * ASPn *  *
         *  ********  *                          *  ********  *
         **************                          **************

                      Figure 1 - Physical Model

In this model, each host has many application processes.  In the case
of the MGC, an ASP may provide service to one or more application
server, and is identified as an SCTP end point.  In the case of the SG,
a pair of signalling gateway processes may represent, as an example, a
single network appearance, serving a signalling point management
cluster.

This example model can also be applied to IPSP-IPSP signalling.  In
this case, each IPSP would have its services distributed across 2 hosts
or more, and may have multiple server processes on each host.

In the example above, each signalling process (SGP, ASP or IPSP) is the
end point to more than one SCTP association, leading to many other
signalling processes.  To support this, a signalling process must be
able to support distribution of M3UA messages to many simultaneous
active associations.  This message distribution function is based on
the status of provisioned routing keys, the availability of signalling
points in the SS7 network, and the redundancy model (active-standby,
load-sharing, n+k) of the remote signalling processes.

For carrier grade networks, Operators should ensure that under the failure or isolation of a particular
signalling process, process SHOULD NOT cause stable calls or transactions are not to be
lost.  This implies that signalling processes need, in some cases, to
share the call call/transaction state or transaction be able to pass the call state
information
with other signalling processes. between each other.  In the case of ASPs performing call
processing, coordination may also be required with the related Media
Gateway to transfer the MGC control for a particular trunk termination.
However, this sharing or communication of call/transaction state
information is outside the scope of this document.

This model serves as an example.  M3UA imposes no restrictions as to
the exact layout of the network elements, the message distribution
algorithms and the distribution of the signalling processes.  Instead,
it provides a framework and a set of messages that allow for a flexible
and scalable signalling network architecture, aiming to provide
reliability and performance.

1.4 Functional Areas

1.4.1 Signalling Point Code Representation

Within an SS7 network, a Signalling Gateway is charged with
representing a set of nodes in the IP domain into the SS7 network for
routing purposes.  The SG itself, as a physical node in the SS7
network, must be addressable with an SS7 Point Code for MTP3 Management
purposes. The SG Point Code may is also be used for addressing any local
MTP3-Users MTP3-
Users at the SG such as an SG-resident SCCP function.

An SG may be logically partitioned to operate in multiple SS7 network
Appearances.  In such a case, the SG must be addressable with a Point
Code in each network appearance, and represents a set of nodes in the
IP domain into each SS7 network.  Alias PCs Point Codes [15] may also be
used within an SG network appearance.

The M3UA places no restrictions on the SS7 Point Code representation of
an AS.  Application Servers can be represented under the same PC Point
Code of the SG, their own individual Point Codes or grouped with other applications
Application Servers for Point Code preservation purposes.  A single
Point Code may be used to represent the SG and all the ASPs Application
Servers together, if desired.

Where Application Servers are grouped under a Point Code address, an
SPMC will include more than one AS. If full advantage of SS7 management
procedures is to be taken (as is advisable in carrier grade networks)
care must be taken that, if (the connection to) one AS of an SPMC
fails, becomes unavailable, all AS
Application Servers of the SPMC fail or become unreachable unavailable from the SG. If
this is not the case,
Otherwise, usage of SS7 transfer prohibited procedures by the SG
becomes problematic as either traffic to the failed unavailable AS cannot be
stopped/diverted or traffic to a still available AS will unnecessarily be
unnecessarily stopped/diverted. (Depending on the network configuration

it may even be necessary to assign an individual SS7 point code to each
AS.)

Observing these principles this principle is of particular importance if alternative
routing possibilities exist on the SS7 level (e.g. via mated SGs) or
application level (e.g. via another MGC/MG).

If an ASP or group of ASPs is available to the SS7 network via more
than one SG, each with its own Point Code, the ASP(s) should be
represented by a Point Code that is separate from any SG Point Code.
This allows these SGs to be viewed from the SS7 network as "STPs", each
having an ongoing  "route" to the same ASP(s).  Under failure
conditions where the ASP(s) become(s) unavailable from one of the SGs,
this approach enables MTP3 route management messaging between the SG
and SS7 network, allowing simple SS7 re-routing through an alternate SG
without changing the Destination Point Code Address of SS7 traffic to
the ASP(s).

Where an AS can be reached via more than one SG it is equally important
that the corresponding Routing Keys in the involved SGs are identical.
(Note: It is possible for the Routing Key configuration data to be
temporarily out-of-synch during configuration updates).

                           +--------+
                           |        |
              +------------+  SG 1  +--------------+
  +-------+   |  SS7 links | "STP"  |  IP network  |     ----
  |  SEP  +---+            +--------+              +---/      \
  |   or  |                                           |  ASPs  |
  |  STP  +---+            +--------+              +---\      /
  +-------+   |            |        |              |     ----
              +------------+  SG 2  +--------------+
                           | "STP"  |
                           +--------+

Note: there is no SG-to-SG communication shown, so each SG can be
reached only via the direct linkset from the SS7 network.

The following example shows a signalling gateway partitioned into two
network appearances.

                               SG
  +-------+              +---------------+
  |  SEP  +--------------| SS7 Ntwk |M3UA|              ----
  +-------+   SS7 links  |   "A"    |    |            /      \
                         |__________|    +-----------+  ASPs  |
                         |          |    |            \      /
  +-------+              | SS7 Ntwk |    |              ----
  |  SEP  +--------------+   "B"    |    |
  +-------+              +---------------+

1.4.2 Message Distribution

1.4.2.1 Address Translation Routing Contexts and Mapping at the SG

In order to direct messages received from the Routing Keys

1.4.2.1 Overview

The distribution of SS7 MTP3 network to the
appropriate IP destination, messages between the SG must perform address translation and
mapping functions using information from the received MTP3-User
message.

To support this message distribution, the SG must maintain the
equivalent of a network address translation table, mapping incoming SS7
message information to an Application Server for a particular
application and range of traffic.  This
Servers is accomplished determined by comparing
elements of the incoming SS7 message to provisioned Routing Keys in the
SG.  These and their associated Routing Keys in turn make reference
Contexts. A Routing Key is essentially a set of SS7 parameters used to an Application Server
filter SS7 messages, whereas the Routing Context parameter is a 4-byte
value (integer) that is enabled by one or more ASP.  These ASPs provide dynamic status
information associated to the SG using various management messages defined that Routing Key in a 1:1
relationship. The Routing Context therefore can be viewed as an index
into a sending node's Message Distribution Table containing the
M3UA protocol. Routing
Key entries.

Possible SS7 address/routing information that comprise a Routing Key
entry includes, for example, the OPC, DPC, SIO found in the MTP3
routing label, or other MTP3-User specific fields such as the ISUP CIC,
SCCP subsystem number, or TCAP transaction ID.  Some example
routing keys Routing
Keys are: the DPC alone, the DPC/OPC combination, the DPC/OPC/CIC
combination, or the DPC/SSN combination.  The particular information
used to define an M3UA Routing Key is application and network
dependent, and none of the above examples are mandated.

An Application Server contains a list of one or Process may be configured to process signalling
traffic related to more ASPs that are
capable of processing than one Application Server, over a single SCTP
Association.  In ASP Active and Inactive management messages, the traffic.  This list is assumed
signalling traffic to be dynamic,
taking into account started or stopped is discriminated by the availability status of
Routing Context parameter.  At an ASP, the individual ASPs in
the list, configuration changes, and possible fail-over mechanisms. The
M3UA protocol includes messages to convey Routing Context parameter
uniquely identifies the availability status range of
the individual ASPs as input to a fail-over mechanism.

Normally, one or more ASPs is active in the ASP (i.e., currently
processing traffic) but in certain failure and transition cases it is
possible signalling traffic associated with
each Application Server that there may not be an active the ASP available.  Both load-
sharing and backup scenarios are supported.

When there is no
configured to receive.

1.4.2.2 Routing Key match for Limitiations

>From an incoming SS7 message, network perspective, a
default treatment must be specified.  Possible solutions are Routing Key is limited to provide within a default Application Server at
single SS7 Destination Point Code. This is important, as the SG that directs all unallocated
traffic must be
able to a (set of) default ASP(s), or present this point code to drop the messages and
provide a notification to management.  The treatment of unallocated
traffic is implementation dependent.

1.4.2.2 Address Translation and Mapping at SS7 network, without
compromising the ASP

In order to direct messages to integrity of the Signaling Point Management Cluster.

Some SS7 network, networks may require the ASP must also
perform an address translation and mapping function in order SG to choose generate UPU messages in
failure conditions. In this case, the proper AS and SG or SGP for may optionally limit a given message.  This is accomplished by
observing the Destination Point Code and other elements
Routing Key to a single Service Indicator (ISUP, TUP, SCCP, etc.).  The
SG generation of a UPU message into the outgoing

message, SS7 network status, SG and SGP availability, and network
appearance configuration tables.

A remote Signalling Gateway may be composed of one or more SGPs that is implementation
dependent, therefore no specific procedures are capable of routing outlined in this
document.

Routing Keys MUST be unique in the sense that a received SS7 traffic.  As signalling
message cannot be matched to more than one Routing Key. It is not
necessary for the case with ASPs, parameter range values within a
dynamic list of SGPs in particular Routing
Key to be contiguous.  For example, an SG can AS could be maintained, taking into account
the availability status configured to

support call processing for multiple ranges of the individual SGPs, configuration changes PSTN trunks that are not
represented by contiguous CIC values.

1.4.2.3 Managing Routing Contexts and fail-over mechanisms. Routing Keys

There is, however, no M3UA messaging are two ways to
manage the status of an SGP. Whenever an SCTP association ways to provision a Routing Key at an SGP
exists, it is assumed to SG. A
Routing Key may be available.  Also, every SGP of one SG
communicating with one ASP regarding one AS provides identical SS7
connectivity configured using an implementation dependent
management interface, statically or dynamically in full accordance to this ASP.

1.4.3 SS7 and M3UA Interworking

In
the case of SS7 and M3UA inter-working, specifications. A Routing Key may also be configured using the
M3UA adaptation layer is
designed to provide an extension dynamic registration/deregistration procedures defined in this
document.  An M3UA element must implement at least one method of
Routing Key provisioning.

When using a management interface to configure Routing Keys, the
message distribution function within the MTP3 defined user primitives.

1.4.3.1 Signalling Gateway SS7 Layers

The SG is responsible for terminating MTP Level 3 of the SS7 protocol,
and offering an IP-based extension not limited to its users.

>From an SS7 perspective, it is expected that the Signalling Gateway
(SG) transmits and receives SS7 set
of parameters defined in this document.  Other implementation dependent
distribution algorithms may be used.

1.4.2.4 Message Signalling Units (MSUs) Distribution the SG

In order to and direct messages received from the PSTN over a standard SS7 MTP3 network interface, using the SS7 Message
Transfer Part (MTP) [14,15,16] to provide reliable transport of the
messages.

As a standard SS7 network interface, the use of MTP Level 2 signalling
links is not
appropriate IP destination, the only possibility.  ATM-based High Speed Links can also
be used with SG must perform a message distribution
function using information from the services of received MTP3-User message.

To support this message distribution, the Signalling ATM Adaptation Layer (SAAL)
[17,18].  It is possible for IP-based links to be present, using SG must maintain the
services
equivalent of the MTP2-User Adaptation Layer (M2UA) [19].  These SS7
datalinks may be terminated at a Signalling Transfer Point (STP) or at network address translation table, mapping incoming SS7
message information to an Application Server for a Signalling End Point (SEP).  Using the services particular
application and range of MTP3, the SG may
be capable traffic.  This is accomplished by comparing
elements of communicating with remote SS7 SEPs in a quasi-associated
fashion, where STPs may be present in the incoming SS7 path between the SEP and message to provisioned Routing Keys in the
SG.

Where ATM-based High Speed Links are used  These Routing Keys in the SS7 network, it is
possible for the SG to use the services of the MTP-3b [20] for reliable
transport turn make reference to and from an SS7 SEP Application Server
that is enabled by one or STP. The maximum Service Data Unit
(SDU) supported by the MTP-3b is 4096 octets compared to the 272-octet
maximum of the MTP3.  However, for MTP3-Users to take advantage of the
larger SDU between MTP3-User peers, network architects should ensure
that MTP3-b is used end-to-end between the SG and the SS7-resident
peer.

1.4.3.2 SS7 more ASPs.  These ASPs provide dynamic status
information on their availability, traffic handling capability and M3UA Inter-Working at
congestion to the SG

The SG provides a functional inter-working of transport functions
between the SS7 network and the IP network by also supporting the M3UA
adaptation layer.  It allows the transfer of MTP3-User signalling using various management messages to and from an IP-based Application Server Process where defined in the
peer MTP3-User protocol layer exists.
M3UA protocol.

The Signalling Gateway must maintain knowledge list of SS7 node and
Signalling Point Management Cluster (SPMC) status in their respective
domains ASPs in order an AS is assumed to perform a seamless inter-working of be dynamic, taking into account
the IP-based
signalling availability, traffic handling capability and the SS7 domains.  For example, SG knowledge of the
availability and/or congestion status of
the SPMC and SS7 nodes must be
maintained individual ASPs in the list, as well as configuration changes and disseminated
possible fail-over mechanisms.

Normally, one or more ASPs are active in the respective networks, AS (i.e., currently
processing traffic) but in order to
ensure that end-to-end operation certain failure and transition cases it is transparent to the communicating
SCN protocol peers at the SS7 node
possible that there may be active ASP available.  Both load-sharing and ASP.
backup scenarios are supported.

When the SG determines that the transport of SS7 messages to an SPMC
(or possibly to parts of an SPMC) there is encountering congestion, the SG
should inform the MTP3 route management function (by no Routing Key match, or only a partial match, for an implementation-
dependent mechanism).  This information is used by the MTP3 to mark the
"route" to the affected destination as congested and to trigger MTP
Transfer Controlled (TFC) messages to any
incoming SS7 SEPs generating traffic message, a default treatment MUST be specified.  Possible
solutions are to the congested DPC, as per current MTP3 procedures.

When provide a default Application Server at the SG determines that the transport of SS7 messages to
directs all ASPs
in unallocated traffic to a particular SPMC is interrupted, then it should similarly inform (set of) default ASP(s), or to
drop the MTP3 route management function.  This information message and provide a notification to management.  The
treatment of unallocated traffic is used by implementation dependent.

1.4.2.5 Message Distribution at the
MTP3 ASP

In order to mark the "route" direct messages to the affected destination as unavailable,
and in SS7 network, the case of ASP must also
perform a message distribution function in order to choose the proper
SG acting as or SGP for a signalling transfer point (i.e., given message.  This is accomplished by observing the
Destination Point Code (and possibly other elements of the SG is different from that of outgoing
message such as the SPMC), to send
MTP Transfer Prohibited (TFP) messages to SLS value), together with the relevant adjacent SS7
nodes, according to destination
availability/restricted/congestion status via the local SS7 network procedures.

When SG(s) and the
availability of the SG determines and SGPs themselves.

A remote Signalling Gateway may be composed of one or more SGPs that the transport
are capable of routing SS7 messages to an ASP in traffic.  As is the case with ASPs, a particular SPMC
dynamic list of SGPs in an SG can be resumed, the SG should similarly inform maintained, taking into account
the
MTP3 route management function.  This information is used by availability status of the MTP3 individual SGPs, configuration changes
and fail-over mechanisms. There is, however, no M3UA messaging to mark
manage the route status of an SGP. Whenever an SCTP association to the affected destination as available, an SGP
exists, it is assumed to be available.  Also, every SGP of one SG
communicating with one ASP regarding one AS provides identical SS7
connectivity to this ASP.

1.4.3 SS7 and in M3UA Interworking

In the case of a signalling transfer point, to send MTP Transfer Allowed (TFA)
messages SS7 and M3UA inter-working, the M3UA adaptation layer is
designed to provide an extension of the relevant adjacent MTP3 defined user primitives.

1.4.3.1 Signalling Gateway SS7 nodes, according to Layers

The SG is responsible for terminating MTP Level 3 of the local SS7
network procedures.

For protocol,
and offering an IP-based extension to its users.

>From an SS7 user part management, perspective, it is required expected that the MTP3-User
protocols at ASPs receive indications of SS7 signalling point
availability, SS7 network congestion, Signalling Gateway
(SG) transmits and remote User Part
unavailability as would be expected in an receives SS7 SEP node.  To accomplish
this, the MTP-PAUSE, MTP-RESUME Message Signalling Units (MSUs) to and MTP-STATUS indication primitives
received at
from the MTP3 upper layer interface at PSTN over a standard SS7 network interface, using the SG need to be
propagated SS7
Message Transfer Part (MTP) [14,15,16] to provide reliable transport of
the remote MTP3-User lower layer interface at messages.

As a standard SS7 network interface, the ASP.
(These indication primitives are, use of course, MTP Level 2 signalling
links is not the only possibility.  ATM-based High Speed Links can also made available to any
existing local MTP3-Users at
be used with the SG, if present.) services of the Signalling ATM Adaptation Layer (SAAL)
[17,18].  It is important possible for IP-based links to clarify that MTP3 management messages such as TFPs be present, using the
services of the MTP2-User Adaptation Layer (M2UA) [19].  These SS7
datalinks may be terminated at a Signalling Transfer Point (STP) or TFAs received from at
a Signalling End Point (SEP).  Using the services of MTP3, the SG may
be capable of communicating with remote SS7 network are not "encapsulated" and sent
blindly to SEPs in a quasi-associated
fashion, where STPs may be present in the ASPs.  Rather, SS7 path between the existing MTP3 management procedures SEP and
the SG.

Where ATM-based High Speed Links are followed within used in the MTP3 function of SS7 network, it is
possible for the SG to re-calculate use the
MTP3 route set status and initiate any required signalling-route-set-
test procedures into services of the SS7 network.  Only when MTP-3b [20] for reliable

transport to and from an SS7 destination
status changes are MTP-PAUSE SEP or MTP-RESUME primitives invoked.  These
primitives can also be invoked due STP. The maximum SIF length
supported by the MTP-3b is 4095 octets compared to local SS7 link set conditions as
per existing MTP3 procedures.

In case where the MTP in 272-octet
maximum of the SG undergoes an MTP restart, event
communication MTP3.  However, for MTP3-Users to take advantage of the concerned ASPs should be handled as follows:

When the SG discovers SS7
larger SDU between MTP3-User peers, network isolation, the SG sends an indication
to all concerned available ASPs (i.e., ASPs in the "active" or
"inactive" state), using a DUNA message.  For the purposes of MTP
Restart, all SPMCs with point codes different from that of the SG with
at least one ASP architects should ensure
that MTP3-b is active or has sent an ASPAC message to used end-to-end between the SG
during the first part of the restart procedure should be considered as
available.  If and the SS7-resident
peer.

1.4.3.2 SS7 and M3UA Inter-Working at the SG receives any ASPAC messages during
the restart procedure, it delays the ASPAC-ACK messages until the end

The SG provides a functional inter-working of transport functions
between the restart procedure.  During the second part of SS7 network and the restart
procedure IP network by also supporting the M3UA at the SG informs all concerned ASPs in the "active"
or "inactive" state of any unavailable SS7 destinations.  At
adaptation layer.  It allows the end transfer of
the restart procedure the M3UA sends an ASPAC-ACK message MTP3-User signalling
messages to all ASPs
in the "active" state.

1.4.3.2 and from an IP-based Application Server

A cluster of application servers is responsible for providing Process where the
overall support for one or more SS7 upper layers.  From an
peer MTP3-User protocol layer exists.

The Signalling Gateway must maintain knowledge of SS7
standpoint, a node and
Signalling Point Management Cluster (SPMC) provides
complete support for the upper layer service for status in their respective
domains in order to perform a given point code.
As an seamless inter-working of the IP-based
signalling and the SS7 domains.  For example, an SPMC providing MGC capabilities must provide complete
support for ISUP for a given point code, according to the local SS7
network specifications.

This measure is necessary to allow the SG to accurately represent knowledge of the
signalling point on
availability and/or congestion status of the local SPMC and SS7 network.

In nodes must be
maintained and disseminated in the case where an ASP respective networks, in order to
ensure that end-to-end operation is connected transparent to more than one SG, the M3UA
must maintain communicating
SCN protocol peers at the status of configured SS7 destinations node and route ASP.

When the SG determines that the transport of SS7 messages according to availability/congestion status of the routes an SPMC
(or possibly to
these destinations.

When parts of an ASP enters SPMC) is encountering congestion, the "Inactive" state towards an SG
should inform the M3UA must MTP3 route management function (by an implementation-
dependent mechanism).  This information is used by the MTP3 to mark all SS7 destinations configured the
"route" to be reachable via this SG as
available.

When the M3UA at an ASP receives a DUNA message indicating SS7 network
isolation at an SG, it will stop any affected traffic via this SG destination as congested and

clear to trigger MTP
Transfer Controlled (TFC) messages to any unavailability state of SS7 destinations via this SG. SEPs generating traffic
to the congested DPC, as per current MTP3 procedures.

When the M3UA subsequently receives any DUNA messages from an SG it will
mark the effected SS7 destinations as unavailable via determines that SG.  When the M3UA receives an ASPAC-ACK message it can resume traffic to
available transport of SS7 destinations via this SG, provided the ASP is in the
active state towards this SG.

1.4.3.3 IPSP

Since IPSPs use M3UA messages to all ASPs
in a point-to-point fashion, there particular SPMC is no concept
of routing of messages beyond interrupted, then it should similarly inform
the remote end.  Therefore, SS7 and M3UA
inter-working MTP3 route management function.  This information is not necessary for this model.

1.4.4 Redundancy Models

The network address translation used by the
MTP3 to mark the "route" to the affected destination as unavailable,
and mapping function in the case of the M3UA layer
supports signalling process fail-over functions in order to support SG acting as a
high availability signalling transfer point (i.e.,
the Point Code of call and transaction processing capability.

1.4.4.1 Application Server Redundancy

All MTP3-User messages (e.g., ISUP, SCCP) incoming to an the SG is different from that of the SPMC), to send
MTP Transfer Prohibited (TFP) messages to the relevant adjacent SS7 network are assigned
nodes, according to a unique Application Server, based on the
information in local SS7 network procedures.

When the message and SG determines that the provisioned Routing Keys.

The Application Server is, in practical terms, a list transport of all ASPs
configured SS7 messages to process an ASP in
a range of MTP3-User traffic defined particular SPMC can be resumed, the SG should similarly inform the
MTP3 route management function.  This information is used by one
Routing Key.  One or more ASPs in the list are normally active (i.e.,
handling traffic) while any others may be unavailable or inactive, MTP3
to
be possibly used mark the route to the affected destination as available, and in the event of failure or unavailability
case of a signalling transfer point, to send MTP Transfer Allowed (TFA)
messages to the
active ASP(s).

The fail-over model supports an "n+k" redundancy model, where "n" ASPs
is relevant adjacent SS7 nodes, according to the minimum number of redundant ASPs local SS7
network procedures.

For SS7 user part management, it is required to handle traffic and
"k" that the MTP3-User
protocols at ASPs are available to take over for a failed or unavailable ASP.  A
"1+1" active/standby redundancy is a subset receive indications of this model. A simplex
"1+0" model is also supported SS7 signalling point
availability, SS7 network congestion, and remote User Part
unavailability as a subset, with no ASP redundancy.

At the SG, would be expected in an Application Server list contains active and inactive ASPs
to support ASP load-sharing SS7 SEP node.  To accomplish
this, the MTP-PAUSE, MTP-RESUME and fail-over procedures.  The list of ASPs
within a logical Application Server is kept updated in MTP-STATUS indication primitives
received at the MTP3 upper layer interface at the SG need to be
propagated to
reflect the active Application Server Process(es).

To avoid a single point remote MTP3-User lower layer interface at the ASP.
(These indication primitives are, of failure, it course, also made available to any
existing local MTP3-Users at the SG, if present.)

It is recommended important to clarify that a minimum of
two ASPs be in the list, resident in separate hosts, and therefore
available over different SCTP Associations.  For example, in MTP3 management messages such as TFPs
or TFAs received from the SS7 network shown in Figure 1, all messages to DPC x could be are not "encapsulated" and sent to ASP1
in Host1 or ASP1 in Host2.  The AS list at SG1 might look like this:

    Routing Key {DPC=x) - "Application Server #1"
        ASP1/Host1  - State=Up, Active
        ASP1/Host2  - State=Up, Inactive

In this "1+1" redundancy case, ASP1 in Host1 would be sent any incoming
message with DPC=x.  ASP1 in Host2 would normally be brought
blindly to the
active state upon failure of, or loss of connectivity to, ASP1/Host1.
In this example, both ASPs ASPs.  Rather, the existing MTP3 management procedures
are Up, meaning that followed within the related SCTP
association MTP3 function of the SG to re-calculate the
MTP3 route set status and far-end M3UA peer is ready.

The AS List at SG1 might to initiate any required signalling-route-
set-test procedures into the SS7 network.  Only when an SS7 destination
status changes are MTP-PAUSE or MTP-RESUME primitives invoked.  These
primitives can also be invoked due to local SS7 link set up in load-share mode:

    Routing Key {DPC=x) - "Application Server #1"
        ASP1/Host1 - State = Up, Active
        ASP1/Host2 - State = Up, Active conditions as
per existing MTP3 procedures.

In this case, both the ASPs would be sent a portion of case where the traffic.
For example MTP in the two ASPs could together form a database, where incoming
queries may be sent SG undergoes an MTP restart, event
communication to any active ASP.

Care must the concerned ASPs should be exercised by a Network Operator in handled as follows:

When the selection of SG discovers SS7 network isolation, the
routing information SG sends an indication
to be used as all concerned available ASPs (i.e., ASPs in the Routing Key for "active" or
"inactive" state), using a particular AS. DUNA message.  For example, where Application Servers are defined using ranges of ISUP
CIC values, the Operator is implicitly splitting up control purposes of MTP
Restart, all SPMCs with point codes different from that of the
related circuit groups.  Some CIC value range assignments may interfere SG with ISUP circuit group management procedures.

In
at least one ASP that is active or that has sent an ASPAC message to
the process SG during the first part of fail-over or fail-back, the restart procedure should be
considered as available.  If the M3UA at the SG receives any ASPAC
messages during the restart procedure, it is recommended that in delays the
case ASPAC-ACK messages
until the end of ASPs supporting call processing, stable calls do not fail.  It
is possible that calls in "transition" may fail, although measures the restart procedure.  During the second part of
communication between the ASPs involved can be used to mitigate this.
For example,
restart procedure the two M3UA at the SG informs all concerned ASPs may share call state via shared memory, in the
"active" or
may use "inactive" state of any unavailable SS7 destinations.  At
the end of the restart procedure the M3UA sends an ASP to ASP protocol ASPAC-ACK message to pass call state information.

1.4.4.2 Signalling Gateway Redundancy

Signalling Gateways may also be distributed over multiple hosts.  Much
like
all ASPs in the AS model, SGs may be comprised "active" state.

1.4.3.3 Application Server

A cluster of application servers is responsible for providing the
overall support for one or more SG Processes
(SGPs), distributed over one or more hosts, using SS7 upper layers.  From an active/standby or
a load-sharing model.  An SGP is viewed as SS7
standpoint, a remote SCTP end-point from
an ASP perspective.  There is, however, no M3UA protocol to manage Signalling Point Management Cluster (SPMC) provides
complete support for the
status of upper layer service for a given point code.
As an SGP. Whenever example, an SCTP association SPMC providing MGC capabilities must provide complete
support for ISUP (and any other MTP3 user located at the point code of
the SPMC) for a given point code, according to an SGP exists, the
SGP local SS7 network
specifications.

This measure is assumed necessary to be available.  Also, every SGP within an allow the SG
communicating with an ASP provides identical SS7 connectivity to this
ASP. Should an SGP lose all or partial SS7 connectivity and other SGPs
exist, accurately represent the SGP must terminate
signalling point on the SCTP associations to local SS7 network.

In the concerned
ASPs.

It is therefore possible for case where an ASP is connected to route signalling messages
destined to the SS7 network using more than one SGP.  In this model, a

Signalling Gateway is deployed as a cluster of hosts acting as a single
SG.  A primary/back-up redundancy model is possible, where SG, the
unavailability of M3UA
must maintain the SCTP association to a primary SGP could be used status of configured SS7 destinations and route
messages according to reroute affected traffic availability/congestion/restricted status of the
routes to these destinations.

When an alternate SGP.  A load-sharing model
is possible, where ASP enters the signalling messages are load-shared between
multiple SGPs.

It may also be possible for "Inactive" state towards an ASP to use more than one SG the M3UA must
mark all SS7 destinations configured to access be reachable via this SG as
available.

When the M3UA at an ASP receives a
specific DUNA message indicating SS7 end point, in a model that resembles network
isolation at an SS7 STP mated
pair.  Typically, SS7 STPs are deployed in mated pairs, with SG, it will stop any affected traffic
load-shared between them.  Other models are also possible, subject to
the limitations via this SG and
clear any unavailability state of the local SS7 network provisioning guidelines.

>From the perspective of destinations via this SG. When
the M3UA at subsequently receives any DUNA messages from an ASP, a particular SG is capable
of transferring it will
mark the effected SS7 destinations as unavailable via that SG.  When
the M3UA receives an ASPAC-ACK message it can resume traffic to an
available SS7 destination if an SCTP association
with at least one SGP of destinations via this SG, provided the SG ASP is established, the SGP has received an
indication from in the ASP
active state towards this SG.

1.4.3.3 IPSP Considerations

Since IPSPs use M3UA that in a point-to-point fashion, there is no concept
of routing of messages beyond the ASP remote end.  Therefore, SS7 and M3UA
inter-working is actively handling traffic not necessary for that destination, this model.

1.4.4 Redundancy Models

The network address translation and mapping function of the SG has not indicated that the destination
is inaccessible.  When an ASP is configured M3UA layer
supports signalling process fail-over functions in order to use multiple SGs for
transferring traffic support a
high availability of call and transaction processing capability.

1.4.4.1 Application Server Redundancy

All MTP3-User messages (e.g., ISUP, SCCP) incoming to an SG from the
SS7 network, network are assigned to a unique Application Server, based on the ASP must maintain
knowledge of
information in the current capability of message and the SGs to handle traffic to
destinations provisioned Routing Keys.

The Application Server is, in practical terms, a list of interest.  This information is crucial all ASPs
configured to the overall
reliability process a range of the service, for both active/standby and load-sharing
model, MTP3-User traffic defined by one
Routing Key.  One or more ASPs in the event of failures, recovery and maintenance activities.
The ASP M3UA may also use this information for congestion avoidance
purposes.

1.4.5 Flow Control
Local Management at an ASP list are normally active (i.e.,
handling traffic) while any others may wish be unavailable or inactive, to stop traffic across an SCTP
association
be possibly used in order to temporarily remove the association from service event of failure or to perform testing and maintenance activity. unavailability of the
active ASP(s).

The function could
optionally be used to control fail-over model supports an "n+k" redundancy model, where "n" ASPs
is the start minimum number of redundant ASPs required to handle traffic on and
"k" ASPs are available to take over for a newly
available SCTP association.

1.4.6 Congestion Management

The M3UA Layer failed or unavailable ASP.  A
"1+1" active/standby redundancy is informed a subset of local this model. A simplex
"1+0" model is also supported as a subset, with no ASP redundancy.

At the SG, an Application Server list contains active and IP network congestion by means inactive ASPs
to support ASP load-sharing and fail-over procedures.  The list of an implementation-dependent function (e.g., an implementation-
dependent indication from ASPs
within a logical Application Server is kept updated in the SCTP of IP network congestion). When an SG determines that to
reflect the transport of SS7 messages to active Application Server Process(es).

To avoid a Signalling Point
Management Cluster (SPMC) is encountering congestion, the SG should
trigger SS7 MTP3 Transfer Controlled management messages to originating
SS7 nodes. The triggering single point of SS7 MTP3 Management messages from an SG is
an implementation-dependent function.

At an ASP, congestion failure, it is indicated to local MTP3-Users by means recommended that a minimum of an
MTP-Status primitive indicating congestion, to invoke appropriate upper
layer responses, as per current MTP3 procedures.

The M3UA should indicate local ASP congestion to
two ASPs be in the SG with an SCON
message.  When an SG receives an SCON message from an ASP it should

trigger SS7 MTP3 Transfer Controlled management list, resident in separate hosts and therefore
available over different SCTP Associations.  For example, in the
network shown in Figure 1, all messages to concerned
SS7 destinations according DPC x could be sent to established MTP procedures.

1.4.7 SCTP Stream Mapping. ASP1
in Host1 or ASP1 in Host2.  The M3UA AS list at both the SG and ASP also supports SG1 might look like the assignment of
signalling traffic into streams within an SCTP association.  Traffic
that requires sequencing must
following:

    Routing Key {DPC=x) - "Application Server #1"
        ASP1/Host1  - State=Up, Active
        ASP1/Host2  - State=Up, Inactive

In this "1+1" redundancy case, ASP1 in Host1 would be assigned to the same stream.  To
accomplish this, MTP3-User traffic may sent any incoming
message with DPC=x.  ASP1 in Host2 would normally be assigned brought to individual
streams based on, for example, the SLS value in the MTP3 Routing Label
active state upon failure of, or the ISUP CIC assignment, subject of course to the maximum number loss of
streams supported by connectivity to, ASP1/Host1.
In this example, both ASPs are Up, meaning that the underlying SCTP association.

The use of related SCTP streams within
association and far-end M3UA peer is recommended ready.

The AS List at SG1 might also be set up in order to minimize
transmission and buffering delays, therefore improving the overall
performance and reliability of load-share mode:

    Routing Key {DPC=x) - "Application Server #1"
        ASP1/Host1 - State = Up, Active
        ASP1/Host2 - State = Up, Active

In this case, both the signalling elements.  The
distribution ASPs would be sent a portion of the MTP3 user messages over traffic.
For example the various streams should
be done in such two ASPs could together form a way database, where incoming
queries may be sent to minimize message mis-sequencing, as required any active ASP.

Care must be exercised by a Network Operator in the SS7 User Parts.

1.4.8 Client/Server Model

The SG takes on the role selection of server while the ASP is
routing information to be used as the client. ASPs
must initiate Routing Key for a particular AS.
For example, where Application Servers are defined using ranges of ISUP
CIC values, the SCTP association to Operator is implicitly splitting up control of the SG.
related circuit groups.  Some CIC value range assignments may interfere
with ISUP circuit group management procedures.

In the process of fail-over, it is recommended that in the case of IPSP to IPSP communication, one side ASPs
supporting call processing, stable calls do not fail.  It is possible
that calls in "transition" MAY fail, although measures of communication
between the ASPs involved can be designated
as used to mitigate this.  For example,
the initiator two ASPs MAY share call state via shared memory, or MAY use an ASP
to ASP protocol to pass call state information.  Any ASP-to-ASP
protocol is outside the scope of this document.

1.4.4.2 Signalling Gateway Redundancy

Signalling Gateways MAY also be distributed over multiple hosts.  Much
like the AS model, SGs may be comprised of one or more SG Processes
(SGPs), distributed over one or more hosts, using an active/standby or
a load-sharing model.  An SGP is viewed as a remote SCTP association and end-point from
an ASP perspective.  There is, however, no M3UA messaging.

The protocol to manage the
status of an SGP. Whenever an SCTP (and UDP/TCP) Registered User Port Number Assignment for M3UA association to an SGP exists, the
SGP is 2905.

1.5 Sample Configurations

1.5.1 Example 1: ISUP message transport

  ********   SS7   *****************   IP   ********
  * SEP  *---------* assumed to be available.  Also, every SGP within an SG       *--------*
communicating with an ASP  *
  ********         *****************        ********

  +------+                                  +------+
  | ISUP |               (NIF)              | ISUP |
  +------+         +------+-+------+        +------+
  | MTP3 |         | MTP3 | | M3UA |        | M3UA |
  +------|         +------+ +------+        +------+
  | MTP2 |         | MTP2 | | SCTP |        | SCTP |
  +------+         +------+ +------+        +------+
  |  L1  |         |  L1  | |  IP  |        |  IP  |
  +------+         +------+ +------+        +------+
      |_______________|         |______________|

    SEP - provides identical SS7 Signalling End Point
    SCTP - Stream Control Transmission Protocol
    NIF - Nodal Inter-working Function

In connectivity to this example, the SG provides
ASP. Should an implementation-dependent nodal
inter-working function (NIF) that allows SGP lose all or partial SS7 connectivity and other SGPs
exist, the MGC SGP must terminate the SCTP associations to exchange SS7 the concerned
ASPs.

It is therefore possible for an ASP to route signalling messages with the SS7-based SEP.  The NIF within
destined to the SG
serves SS7 network using more than one SGP.  In this model, a
Signalling Gateway is deployed as a cluster of hosts acting as a single
SG.  A primary/back-up redundancy model is possible, where the interface within the SG between
unavailability of the MTP3 and M3UA.  This
nodal inter-working function has no visible peer protocol with either SCTP association to a primary SGP could be used
to reroute affected traffic to an alternate SGP.  A load-sharing model
is possible, where the MGC or SEP. signalling messages are load-shared between
multiple SGPs.

It may also provides network status information be possible for an ASP to use more than one or
both sides of the network.

For internal SG modeling purposes, at the NIF level, to access a
specific SS7 signalling
messages end point, in a model that resembles an SS7 STP mated
pair.  Typically, SS7 STPs are destined to the MGC are received as MTP-TRANSFER
indication primitives from the MTP Level 3 upper layer interface and deployed in mated pairs, with traffic
load-shared between them.  Other models are sent also possible, subject to
the limitations of the local M3UA-resident message distribution function for
ongoing routing to SS7 network provisioning guidelines.

>From the final IP destination.  MTP-TRANSFER primitives
received from perspective of the local M3UA network address translation and mapping
function are sent to the MTP Level 3 upper layer interface as MTP-
TRANSFER request primitives for on-going MTP Level 3 routing at an ASP, a particular SG is capable
of transferring traffic to an SS7
SEP.  For the purposes destination if an SCTP association
with at least one SGP of providing SS7 network status information the
NIF also delivers MTP-PAUSE, MTP-RESUME and MTP-STATUS indication
primitives received from SG is established, the MTP Level 3 upper layer interface SGP has returned an
ASPAC Ack message acknowledging to the
local M3UA-resident management function.

1.5.2  Example 2: SCCP Transport between IPSPs

   ********    IP    ********
   * IPSP *          * IPSP *
   ********          ********

   +------+          +------+
   |SCCP- |          |SCCP- |
   | User |          | User |
   +------+          +------+
   | SCCP |          | SCCP |
   +------+          +------+
   | M3UA |          | ASP M3UA |
   +------+          +------+
   | SCTP |          | SCTP |
   +------+          +------+
   |  IP  |          |  IP  |
   +------+          +------+
       |________________|

This example shows an architecture where no Signalling Gateway is used.
In this example, SCCP messages are exchanged directly between two IP-
resident IPSPs with resident SCCP-User protocol instances, such as
RANAP or TCAP.  SS7 network inter-working that the ASP is
actively handling traffic for that destination, and the SG has not required, therefore
there
indicated that the destination is no MTP3 network management status information inaccessible.  When an ASP is
configured to use multiple SGs for the SCCP and
SCCP-User protocols transferring traffic to consider.  Any MTP-PAUSE, -RESUME or -STATUS
indications from the M3UA to SS7
network, the SCCP should consider only ASP must maintain knowledge of the status current capability of
the SCTP Association and underlying IP network.

1.5.3 Example 3: SG resident SCCP layer, with remote ASP

  ********   SS7   *****************   IP   ********
  * SEP  *---------*               *--------*      *
  *  or  *         *      SG       *        * ASP  *
  * STP  *         *               *        *      *
  ********         *****************        ********

  +------+         +---------------+        +------+
  | SCCP-|         |     SCCP      |        | SCCP-|
  | User |         +---------------+        | User |
  +------+           |   _____   |          +------+
  | SCCP |           |  |     |  |          | SCCP |
  +------+         +------+-+------+        +------+
  | MTP3 |         | MTP3 | | M3UA |        | M3UA |
  +------|         +------+ +------+        +------+
  | MTP2 |         | MTP2 | | SCTP |        | SCTP |
  +------+         +------+ +------+        +------+
  |  L1  |         |  L1  | |  IP  |        |  IP  |
  +------+         +------+ +------+        +------+
      |_______________|         |______________|

    STP - SS7 Signalling Transfer Point

In this example, SGs to handle traffic to destinations of interest.  This
information is crucial to the SG contains an instance overall reliability of the SS7 SCCP protocol
layer that may, service, for example, perform
both active/standby and load-sharing model, in the SCCP Global Title Translation
(GTT) function event of failures,
recovery and maintenance activities.  The ASP M3UA may also use this
information for messages logically addressed to congestion avoidance purposes.  The distribution of the SG SCCP.  If
MTP3-user messages over the
result of SGs should be done in such a GTT for an SCCP way to
minimize message yields an mis-sequencing, as required by the SS7 DPC or DPC/SSN
address result of User Parts.

1.4.5 Flow Control
Local Management at an SCCP peer located ASP may wish to stop traffic across an SCTP
association in the IP domain, the resulting
MTP-TRANSFER request primitive is sent order to temporarily remove the local M3UA-resident
network address translation and mapping function for ongoing routing to
the final IP destination.

Similarly, the SCCP instance in an SG can perform the SCCP GTT association from service
for messages logically addressed
or to it from SCCP peers in the IP
domain.  In this case, MTP-TRANSFER messages are sent from the local
M3UA-resident network address translation perform testing and mapping maintenance activity.  The function could
optionally be used to control the
SCCP for GTT.  If the result start of the GTT yields the address traffic on to a newly
available SCTP association.

1.4.6 Congestion Management

The M3UA Layer is informed of local and IP network congestion by means
of an SCCP
peer in implementation-dependent function (e.g., an implementation-
dependent indication from the SS7 SCTP of IP network then congestion).

At an ASP or IPSP, the resulting MTP-TRANSFER request is
given M3UA indicates congestion to the local MTP3-Users by
means of an MTP-Status primitive, as per current MTP3 for delivery procedures, to
invoke appropriate upper layer responses.

When an SS7-resident node.

It is possible SG determines that the above SCCP GTT at transport of SS7 messages to a
Signalling Point Management Cluster (SPMC) is encountering congestion,
the SG could yield the
address should trigger SS7 MTP3 Transfer Controlled management messages
to originating SS7 nodes, as per current MTP3 procedures. The
triggering of SS7 MTP3 Management messages from an SCCP peer in the IP domain and the resulting MTP-TRANSFER
primitive would be sent back to the SG is an
implementation-dependent function.

The M3UA for delivery at an ASP or IPSP should indicate local congestion to an IP
destination.

For internal SG modeling purposes, this may be accomplished M3UA
peer with the
use of an implementation-dependent nodal inter-working function within SCON message.  When an SG M3UA receives an SCON message
from an ASP, and the SG determines that effectively sits below the SCCP and routes MTP-TRANSFER an SPMC is now encountering
congestion, it should trigger SS7 MTP3 Transfer Controlled management
messages to/from to concerned SS7 destinations according to current MTP
procedures.

1.4.7 SCTP Stream Mapping.

The M3UA at both the MTP3 SG and ASP also supports the M3UA, assignment of
signalling traffic into streams within an SCTP association.  Traffic
that requires sequencing must be assigned to the same stream.  To
accomplish this, MTP3-User traffic may be assigned to individual
streams based on on, for example, the SS7 DPC or
DPC/SSN

address information.  This nodal inter-working function has no visible
peer protocol with either SLS value in the ASP MTP3 Routing Label
or SEP.

Note that the services and interface provided ISUP CIC assignment, subject of course to the maximum number of
streams supported by the underlying SCTP association.

The use of SCTP streams within M3UA are the same
as is recommended in Example 1 order to minimize
transmission and buffering delays, therefore improving the functions taking place in overall
performance and reliability of the SCCP entity are
transparent to M3UA. signalling elements.  The SCCP protocol functions are not reproduced in
the M3UA protocol.

1.6 Definition of M3UA Boundaries

1.6.1 Definition
distribution of the boundary between M3UA and an MTP3-User.

>From ITU Q.701 [14]:

   MTP-TRANSFER request
   MTP-TRANSFER indication
   MTP-PAUSE indication
   MTP-RESUME indication
   MTP-STATUS indication

1.6.2 Definition of MTP3 user messages over the boundary between M3UA and SCTP

The upper layer primitives provided various streams should
be done in such a way to minimize message mis-sequencing, as required
by the SCTP are provided in [13]

1.6.3 Definition SS7 User Parts.

1.4.8 Client/Server Model

The SG takes on the role of server while the Boundary between M3UA and Layer Management

   M-SCTP ESTABLISH request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to establish an SCTP association with an SG
            or IPSP.

   M-STCP ESTABLISH confirm
   Direction: M3UA -> LM
   Purpose: ASP confirms to LM that it has established an SCTP
            association with an SG or IPSP.

   M-SCTP ESTABLISH indication
   Direction: M3UA -> LM
   Purpose: M3UA informs LM that a remote ASP has established an SCTP
            association.

   M-SCTP RELEASE request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to release an is the client. ASPs
MUST initiate the SCTP association with SG or
            IPSP.

   M-SCTP RELEASE confirm
   Direction: M3UA -> LM
   Purpose: ASP confirms to LM that it has released SCTP association
            with the SG.

   M-SCTP RELEASE indication
   Direction: M3UA -> LM
   Purpose: M3UA informs LM that a remote ASP has released an SCTP
            Association or

In the SCTP association has failed.

   M-SCTP STATUS request
   Direction: LM -> M3UA
   Purpose: LM requests M3UA case of IPSP to report IPSP communication, the status of an SCTP
            association.

   M-SCTP STATUS confirm
   Direction: M3UA -> LM
   Purpose: peer endpoints using
M3UA reports SHOULD be configured so that one always takes on the status role of an SCTP association.

   M-ASP STATUS request
   Direction: LM -> M3UA
   Purpose: LM requests M3UA to report
client and the status other the role of a local or remote
            ASP.

   M-ASP STATUS confirm
   Direction: server for initiating SCTP
associations and M3UA -> LM
   Purpose: messaging.

The SCTP (and UDP/TCP) Registered User Port Number Assignment for M3UA reports status of local or remote ASP.

   M-AS STATUS request
   Direction: LM ->
is 2905.

1.5 Sample Configurations

1.5.1 Example 1: ISUP message transport

  ********   SS7   *****************   IP   ********
  * SEP  *---------*      SG       *--------* ASP  *
  ********         *****************        ********

  +------+                                  +------+
  | ISUP |               (NIF)              | ISUP |
  +------+         +------+-+------+        +------+
  | MTP3 |         | MTP3 | | M3UA
   Purpose: LM requests |        | M3UA to report |
  +------|         +------+ +------+        +------+
  | MTP2 |         | MTP2 | | SCTP |        | SCTP |
  +------+         +------+ +------+        +------+
  |  L1  |         |  L1  | |  IP  |        |  IP  |
  +------+         +------+ +------+        +------+
      |_______________|         |______________|

    SEP - SS7 Signalling End Point
    SCTP - Stream Control Transmission Protocol
    NIF - Nodal Inter-working Function

In this example, the status of SG provides an AS.

   M-AS STATUS confirm
   Direction: M3UA -> LM
   Purpose: M3UA reports implementation-dependent nodal
inter-working function (NIF) that allows the MGC to exchange SS7
signalling messages with the SS7-based SEP.  The NIF within the SG
serves as the interface within the SG between the MTP3 and M3UA.  This
nodal inter-working function has no visible peer protocol with either
the MGC or SEP.  It also provides network status information to one or
both sides of an AS.

   M-NOTIFY indication
   Direction: M3UA -> LM
   Purpose: M3UA reports the network.

For internal SG modeling purposes, at the NIF level, SS7 signalling
messages that it has are destined to the MGC are received a NOTIFY message
            from its peer.

   M-ERROR as MTP-TRANSFER
indication
   Direction: M3UA -> LM
   Purpose: M3UA reports that it has received an ERROR message primitives from
            its peer or that a the MTP Level 3 upper layer interface and
are sent to the local operation has been unsuccessful.

   M-ASP UP request
   Direction: LM -> M3UA
   Purpose: LM requests ASP M3UA-resident message distribution function for
ongoing routing to start its operation the final IP destination.  MTP-TRANSFER primitives
received from the local M3UA network address translation and send an ASP-UP
            Message mapping
function are sent to its peer.

   M-ASP UP confirm
   Direction: M3UA -> LM
   Purpose: M3UA confirms requested ASP-UP change has been successfully
            acknowledged by the M3UA peer.

   M-ASP UP indication
   Direction: M3UA -> LM
   Purpose: M3UA reports it has successfully processed an incoming ASP-
            UP request from its peer.

   M-ASP DOWN MTP Level 3 upper layer interface as MTP-
TRANSFER request
   Direction: LM -> M3UA
   Purpose: LM requests ASP primitives for on-going MTP Level 3 routing to stop its operation and send an ASP-DOWN
            Message to its peer.

   M-ASP DOWN confirm
   Direction: M3UA -> LM
   Purpose: M3UA confirms requested ASP-DOWN change has been
            successfully acknowledged by SS7
SEP.  For the M3UA peer.

   M-ASP DOWN purposes of providing SS7 network status information the
NIF also delivers MTP-PAUSE, MTP-RESUME and MTP-STATUS indication
   Direction: M3UA -> LM
   Purpose: M3UA reports it has successfully processed an incoming ASP-
            DOWN request
primitives received from its peer.

   M-ASP-ACTIVE request
   Direction: LM -> M3UA
   Purpose: LM requests ASP the MTP Level 3 upper layer interface to send the
local M3UA-resident management function. In addition, as an ASP-ACTIVE message to its peer
implementation and network option, restricted destinations are
communicated from MTP network management to start data transfer.

   M-ASP ACTIVE confirm
   Direction: M3UA -> LM
   Purpose: LM confirms requested ASP-ACTIVE change has been
            successfully acknowledged by the local M3UA-resident
management function.

1.5.2  Example 2: SCCP Transport between IPSPs

        ********    IP    ********
        * IPSP *          * IPSP *
        ********          ********

        +------+          +------+
        |SCCP- |          |SCCP- |
        | User |          | User |
        +------+          +------+
        | SCCP |          | SCCP |
        +------+          +------+
        | M3UA peer.

   M-ASP ACTIVE indication
   Direction: |          | M3UA -> LM
   Purpose: LM reports it has successfully processed |
        +------+          +------+
        | SCTP |          | SCTP |
        +------+          +------+
        |  IP  |          |  IP  |
        +------+          +------+
            |________________|

This example shows an incoming ASP-
            ACTIVE request from its peer.

   M-ASP-INACTIVE request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to stop data transfer architecture where no Signalling Gateway is used.
In this example, SCCP messages are exchanged directly between two IP-
resident IPSPs with resident SCCP-User protocol instances, such as
RANAP or TCAP.  SS7 network inter-working is not required, therefore
there is no MTP3 network management status information for the SCCP and send an ASP-
            Inactive message
SCCP-User protocols to the SG.

   M-ASP INACTIVE confirm
   Direction: LM -> M3UA
   Purpose: LM confirms requested ASP-INACTIVE change has been
            successfully acknowledged by the M3UA peer.

   M-ASP INACTIVE indication
   Direction: M3UA -> LM
   Purpose: LM reports it has successfully processed an incoming ASP-
            INACTIVE request consider.  Any MTP-PAUSE, -RESUME or -STATUS
indications from its peer.

   M-AS ACTIVE indication
   Direction: M3UA -> LM
   Purpose: LM reports that an AS has moved to the ACTIVE state.

   M-AS INACTIVE indication
   Direction: M3UA -> LM
   Purpose: LM reports that an AS has moved to the INACTIVE state.

   M-AS DOWN indication
   Direction: M3UA -> LM
   Purpose: LM reports that an AS has moved to SCCP should consider the DOWN state.

2.0 Conventions

The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD
NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when they appear
in this document, are to be interpreted as described in [RFC2119].

3.0 M3UA Protocol Elements

The general M3UA message format includes a Common Message Header
followed by zero or more parameters as defined by status of the Message Type.
For forward compatibility, all Message Types may have attached
parameters even if none are specified in this version.

3.1 Common Message Header

The protocol messages for MTP3-User Adaptation require a message
structure that contains a version, message type, message length,
SCTP Association and
message contents.  This message header is common among all signalling
protocol adaptation layers:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ underlying IP network and any congestion
information received from the remote site.

1.5.3 Example 3: SG resident SCCP layer, with remote ASP

  ********   SS7   *****************   IP   ********
  * SEP  *---------*               *--------*      *
  *  or  *         *      SG       *        * ASP  *
  * STP  *         *               *        *      *
  ********         *****************        ********

  +------+         +---------------+        +------+
  |    Version SCCP-|         |   Reserved     SCCP      | Message Class        | Message Type SCCP-|
  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ User |         +---------------+        | User |
  +------+           |   _____   |          +------+
  | SCCP |           |  |     |  |          | SCCP |
  +------+         +------+-+------+        +------+
  | MTP3 |         | MTP3 |                        Message Length |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                                                               /

All fields in an M3UA message MUST be transmitted in the network byte
order, unless otherwise stated.

M3UA Protocol Version: 8 bits (unsigned integer)

   The version field contains the version of the M3UA adaptation layer.
   The supported versions are:

         1      Release 1.0

Message Class: 8 bits (unsigned integer)

   The following list |        | M3UA |
  +------|         +------+ +------+        +------+
  | MTP2 |         | MTP2 | | SCTP |        | SCTP |
  +------+         +------+ +------+        +------+
  |  L1  |         |  L1  | |  IP  |        |  IP  |
  +------+         +------+ +------+        +------+
      |_______________|         |______________|

    STP - SS7 Signalling Transfer Point

In this example, the SG contains an instance of the Message Type Classes SS7 SCCP protocol
layer that may, for example, perform the defined
   messages.

         0        Management (MGMT) Message
         1        Transfer Messages
         2        SS7 Signalling Network Management (SSNM) Messages
         3        ASP State Maintenance (ASPSM) Messages
         4        ASP Traffic Maintenance (ASPTM) Messages
      5 SCCP Global Title Translation
(GTT) function for messages logically addressed to 255    Reserved

Message Type: 8 bits (unsigned integer)

   The following list contains the message types SG SCCP.  If the
result of a GTT for an SCCP message yields an SS7 DPC or DPC/SSN
address an SCCP peer located in the defined
   messages.

     Management (MGMT) Message

         0        Error (ERR)
         1        Notify (NTFY)
       2 IP domain, the resulting MTP-
TRANSFER request primitive is sent to 255   Reserved the local M3UA-resident network
address translation and mapping function for Management Messages

     Transfer Messages

         0        Reserved
         1        Payload Data (DATA)
       2 ongoing routing to 255   Reserved for Transfer Messages

     SS7 Signalling Network Management (SSNM) Messages

         0        Reserved
         1        Destination Unavailable (DUNA)
         2        Destination Available (DAVA)
         3        Destination State Audit (DAUD)
         4        SS7 Network Congestion State (SCON)
         5        Destination User Part Unavailable (DUPU)
       6 to 255   Reserved the
final IP destination.

Similarly, the SCCP instance in an SG can perform the SCCP GTT service
for SSNM Messages
  ASP State Maintenance (ASPSM) Messages

         0        Reserved
         1        ASP Up (UP)
         2        ASP Down (DOWN)
         3        Heartbeat (BEAT)
         4        ASP Up Ack (UP ACK)
         5        ASP Down Ack (DOWN ACK)
         6        Heatbeat Ack (BEAT ACK)

       7 messages logically addressed to 255   Reserved it from SCCP peers in the IP
domain.  In this case, MTP-TRANSFER messages are sent from the local
M3UA-resident network address translation and mapping function to the
SCCP for ASPSM Messages

  ASP Traffic Maintenance (ASPTM) Messages

         0        Reserved
         1        ASP Active (ACTIVE)
         2        ASP Inactive (INACTIVE)
         3        ASP Active Ack (ACTIVE ACK)
         4        ASP Inactive Ack (INACTIVE ACK)
       5 GTT.  If the result of the GTT yields the address of an SCCP
peer in the SS7 network then the resulting MTP-TRANSFER request is
given to 255   Reserved the MTP3 for ASPTM Messages

Reserved: 8 bits

   Should be set delivery to all '0's and ignored by an SS7-resident node.

It is possible that the receiver.

Message Length: 32-bits (unsigned integer)

   The Message Length defines above SCCP GTT at the length of SG could yield the message
address of an SCCP peer in octets,
   including the header.

3.2 Variable-Length Parameter Format

M3UA messages consist of a Common Header followed by zero or more
parameters, as defined by IP domain and the message type.  The variable-length
parameters contained in a message are defined in a Tag-Length-Value
format as shown below.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |          Parameter Tag        |       Parameter Length        |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  \                                                               \
  /                       Parameter Value                         /
  \                                                               \
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameter Tag: 16 bits (unsigned integer)

   Tag field is a 16-bit identifier of the type of parameter. It takes
   a value of 0 resulting MTP-TRANSFER
primitive would be sent back to 65534.

   The value of 65535 is reserved for IETF-defined extensions.  Values
   other than those defined in specific parameter description are
   reserved the M3UA for delivery to an IP
destination.

For internal SG modeling purposes, this may be accomplished with the
use of an implementation-dependent nodal inter-working function within
the SG that effectively sits below the SCCP and routes MTP-TRANSFER
messages to/from both the MTP3 and the M3UA, based on the SS7 DPC or
DPC/SSN

address information.  This nodal inter-working function has no visible
peer protocol with either the ASP or SEP.

Note that the services and interface provided by the IETF.

Parameter Length: 16 bits (unsigned integer)

   The Parameter Length field contains M3UA are the size of same
as in Example 1 and the parameter functions taking place in
   bytes, including the Parameter Tag, Parameter Length, and Parameter
   Value fields. SCCP entity are
transparent to M3UA.  The Parameter Length does SCCP protocol functions are not include any padding
   bytes.

Parameter Value: variable-length.

   The Parameter Value field contains the actual information to be
   transferred reproduced in
the parameter.

   The total length M3UA protocol.

1.6 Definition of a parameter (including Tag, Parameter Length and
   Value fields) MUST be a multiple M3UA Boundaries

1.6.1 Definition of 4 bytes. If the length boundary between M3UA and an MTP3-User.

>From ITU Q.701 [14]:

   MTP-TRANSFER request
   MTP-TRANSFER indication
   MTP-PAUSE indication
   MTP-RESUME indication
   MTP-STATUS indication

1.6.2 Definition of the
   parameter is not a multiple boundary between M3UA and SCTP

An example of 4 bytes, the sender pads the
   Parameter at the end (i.e., after the Parameter Value field) with
   all zero bytes. The length of upper layer primitives provided by the padding is NOT included SCTP are
provided in Reference [13] Section 10.

1.6.3 Definition of the
   parameter length field. A sender should NEVER pad with more than 3
   bytes. The receiver MUST ignore the padding bytes.

3.3 Transfer Messages

The following section describes the Transfer messages Boundary between M3UA and parameter
contents.

3.3.1 Payload Data Message (DATA)

The Data message contains the SS7 MTP3-User protocol data, which is Layer Management

   M-SCTP ESTABLISH request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to establish an
MTP-TRANSFER primitive, including the complete MTP3 Routing Label. The
Data message contains the following variable length parameters:

     Network Appearance    Optional
     Protocol Data         Mandatory

The following format MUST be used for the Data Message:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1            |          Length = 8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Network Appearance*                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 3            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                        Protocol Data                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Network Appearance: 32-bits (unsigned integer)

   The optional Network Appearance parameter identifies the SS7 network
   context for the message, for the purposes of logically separating
   the signalling traffic between the SG and the Application Server
   Process over a common SCTP Association.  An example is where association with an SG
   is logically partitioned
            SG.

   M-STCP ESTABLISH confirm
   Direction: M3UA -> LM
   Purpose: ASP confirms to appear as LM that it has established an element in four different
   national SS7 networks.

   In SCTP
            association with an SG.

   M-SCTP ESTABLISH indication
   Direction: M3UA -> LM
   Purpose: M3UA informs LM that a Data message, the Network Appearance implicitly defines the SS7
   Point Code format used, the SS7 Network Indicator value, and the
   MTP3/MTP3-User protocol type/variant/version used within the SS7
   network partition.  Where remote ASP has established an SG operates in the context of SCTP
            association.

   M-SCTP RELEASE request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to release an SCTP association with SG.

   M-SCTP RELEASE confirm
   Direction: M3UA -> LM
   Purpose: ASP confirms to LM that it has released SCTP association
            with SG.

   M-SCTP RELEASE indication
   Direction: M3UA -> LM
   Purpose: M3UA informs LM that a single
   SS7 network, remote ASP has released an SCTP
            Association or individual the SCTP associations are dedicated association has failed.

   M-SCTP STATUS request
   Direction: LM -> M3UA
   Purpose: LM requests M3UA to each
   SS7 network context, report the Network Appearance parameter is not
   required.

   The Network Appearance parameter value is status of local significance
   only, coordinated between the SG and ASP.

   Where the an SCTP
            association.

   M-SCTP STATUS confirm
   Direction: M3UA -> LM
   Purpose: M3UA reports the status of an SCTP association.

   M-ASP STATUS request
   Direction: LM -> M3UA
   Purpose: LM requests M3UA to report the status of a local or remote
            ASP.

   M-ASP STATUS confirm
   Direction: M3UA -> LM
   Purpose: M3UA reports status of local or remote ASP.

   M-AS STATUS request
   Direction: LM -> M3UA
   Purpose: LM requests M3UA to report the status of an AS.

   M-AS STATUS confirm
   Direction: M3UA -> LM
   Purpose: M3UA reports the status of an AS.

   M-NOTIFY indication
   Direction: M3UA -> LM
   Purpose: M3UA reports that it has received a NOTIFY message
            from its peer.

   M-ERROR indication
   Direction: M3UA -> LM
   Purpose: M3UA reports that it has received an ERROR message from
            its peer or that a local operation has been unsuccessful.

   M-ASP UP request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to start its operation and send an ASP-UP
            Message to its peer.

   M-ASP UP confirm
   Direction: M3UA -> LM
   Purpose: ASP reports that is has received an ASP UP Acknowledgement
            message from the SG.

   M-ASP UP indication
   Direction: M3UA -> LM
   Purpose: M3UA reports it has successfully processed an incoming ASP-
            UP request from its peer.

   M-ASP DOWN request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to stop its operation and send an ASP-DOWN
            Message to its peer.

   M-ASP DOWN confirm
   Direction: M3UA -> LM
   Purpose: ASP reports that is has received an ASP DOWN
            Acknowledgement message from the SG.

   M-ASP DOWN indication
   Direction: M3UA -> LM
   Purpose: M3UA reports it has successfully processed an incoming ASP-
            DOWN request from its peer.

   M-ASP-ACTIVE request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to send an ASP-ACTIVE message to its peer.

   M-ASP ACTIVE confirm
   Direction: M3UA -> LM
   Purpose: ASP reports that is has received an ASP ACTIVE
            Acknowledgement message from the SG.

   M-ASP ACTIVE indication
   Direction: M3UA -> LM
   Purpose: LM reports it has successfully processed an incoming ASP-
            ACTIVE request from its peer.

   M-ASP-INACTIVE request
   Direction: LM -> M3UA
   Purpose: LM requests ASP to send an ASP- Inactive message to the SG.

   M-ASP INACTIVE confirm
   Direction: LM -> M3UA
   Purpose: ASP reports that is has received an ASP INACTIVE
            Acknowledgement message from the SG.

   M-ASP INACTIVE indication
   Direction: M3UA -> LM
   Purpose: LM reports it has successfully processed an incoming ASP-
            INACTIVE request from its peer.

   M-AS ACTIVE indication
   Direction: M3UA -> LM
   Purpose: LM reports that an AS has moved to the ACTIVE state.

   M-AS INACTIVE indication
   Direction: M3UA -> LM
   Purpose: LM reports that an AS has moved to the INACTIVE state.

   M-AS DOWN indication
   Direction: M3UA -> LM
   Purpose: LM reports that an AS has moved to the DOWN state.

2.0 Conventions

The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD
NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when they appear
in this document, are to be interpreted as described in [RFC2119].

3.0 M3UA Protocol Elements

The general M3UA message format includes a Common Message Header
followed by zero or more parameters as defined by the Message Type.
For forward compatibility, all Message Types may have attached
parameters even if none are specified in this version.

3.1 Common Message Header

The protocol messages for MTP3-User Adaptation require a message header
which contains the adaptation layer version, the message type, and
message length.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Version    |   Reserved    | Message Class | Message Type  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Message Length                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                                                               /

All fields in an M3UA message MUST be transmitted in the network byte
order, unless otherwise stated.

3.1.1 M3UA Protocol Version: 8 bits (unsigned integer)

   The version field contains the version of the M3UA adaptation layer.

   The supported versions are the following:

         1      Release 1.0

3.1.2  Message Classes and Types

The following list contains the valid Message Classes:

Message Class: 8 bits (unsigned integer)

   The following list contains the valid Message Type Classes:

     0     Management (MGMT) Message [IUA/M2UA/M3UA/SUA]
     1     Transfer Messages [M3UA]
     2     SS7 Signalling Network Management (SSNM) Messages [M3UA/SUA]
     3     ASP State Maintenance (ASPSM) Messages [IUA/M2UA/M3UA/SUA]
     4     ASP Traffic Maintenance (ASPTM) Messages [IUA/M2UA/M3UA/SUA]
     5     Q.921/Q.931 Boundary Primitives Transport (QPTM) Messages
              [IUA]
     6     MTP2 User Adaptation (MAUP) Messages [M2UA]
     7     Connectionless Messages [SUA]
     8     Connection-Oriented Messages [SUA]
     9     Routing Key Management (RKM) Messages (M3UA)
  10 to 127 Reserved by the IETF
  28 to 255 Reserved for IETF-Defined Message Class extensions

Message Type: 8 bits (unsigned integer)

   The following list contains the message types for the defined
   messages.

     Management (MGMT) Message

         0        Error (ERR)
         1        Notify (NTFY)
      2 to 127    Reserved by the IETF
    128 to 255    Reserved for IETF-Defined MGMT extensions

     Transfer Messages

         0        Reserved
         1        Payload Data (DATA)
      2 to 127    Reserved by the IETF
    128 to 255    Reserved for IETF-Defined Transfer extensions
     SS7 Signalling Network Management (SSNM) Messages

         0        Reserved
         1        Destination Unavailable (DUNA)
         2        Destination Available (DAVA)
         3        Destination State Audit (DAUD)
         4        SS7 Network Congestion State (SCON)
         5        Destination User Part Unavailable (DUPU)
         6        Destination Restricted (DRST)
      7 to 127    Reserved by the IETF
    128 to 255    Reserved for IETF-Defined SSNM extensions

  ASP State Maintenance (ASPSM) Messages

         0        Reserved
         1        ASP Up (UP)
         2        ASP Down (DOWN)
         3        Heartbeat (BEAT)
         4        ASP Up Ack (UP ACK)
         5        ASP Down Ack (DOWN ACK)
         6        Heatbeat Ack (BEAT ACK)
      7 to 127    Reserved by the IETF
    128 to 255    Reserved for IETF-Defined ASPSM extensions

  ASP Traffic Maintenance (ASPTM) Messages

         0        Reserved
         1        ASP Active (ACTIVE)
         2        ASP Inactive (INACTIVE)
         3        ASP Active Ack (ACTIVE ACK)
         4        ASP Inactive Ack (INACTIVE ACK)
      5 to 127    Reserved by the IETF
    128 to 255    Reserved for IETF-Defined ASPTM extensions

  Routing Key Management (RKM) Messages

         0        Reserved
         1        Registration Request (REG REQ)
         2        Registration Response (REG RSP)
         3        Deregistration Request (DEREG REQ)
         4        Deregistration Response (DEREG RSP)
      5 to 127    Reserved by the IETF
    128 to 255    Reserved for IETF-Defined ASPTM extensions

3.1.3  Reserved: 8 bits

   The Reserved field SHOULD be set to all '0's and ignored by the
   receiver.

3.1.4  Message Length: 32-bits (unsigned integer)

   The Message Length defines the length of the message in octets,
   including the Common Header.  For messages with a final parameter
   containing padding, the parameter padding MUST be included in the
   Message Length.

   Note: A receiver SHOULD accept the message whether or not the final
   parameter padding is included in the message length.

3.2 Variable-Length Parameter Format

M3UA messages consist of a Common Header followed by zero or more
variable length parameters, as defined by the message type.  All the
parameters contained in a message are defined in a Tag-Length-Value
format as shown below.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |          Parameter Tag        |       Parameter Length        |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  \                                                               \
  /                       Parameter Value                         /
  \                                                               \
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Where more than one parameter is included in a message, the parameters
may be in any order, except where explicitly mandated.  A receiver
SHOULD accept the parameters in any order.

Parameter Tag: 16 bits (unsigned integer)

   The Tag field is a 16-bit identifier of the type of parameter. It
   takes a value of 0 to 65534.  The parameter Tags defined are as
   follows:

         0        Reserved
         1        Network Appearance
         2        Protocol Data 1
         3        Protocol Data 2
         4        Info String
         5        Affected Destinations
         6        Routing Context
         7        Diagnostic Information
         8        Heartbeat Data
         9        User/Cause
        10        Reason
        11        Traffic Mode Type
        12        Error Code
        13        Status Type/ID
        14        Congestion Indications
        15        Concerned Destination
        16        Routing Key
        17        Registration Result
        18        De-registration Result
        19        Local_Routing Key Identifier
        20        Destination Point Code
        21        Service Indicators
        22        Subsystem Numbers
        23        Originating Point Code List
        24        Circuit Range
        25        Registration Results
        26        De-Registration Results
     27 to 65534  Reserved by the IETF

   The value of 65535 is reserved for IETF-defined extensions.  Values
   other than those defined in specific parameter description are
   reserved for use by the IETF.

Parameter Length: 16 bits (unsigned integer)

   The Parameter Length field contains the size of the parameter in
   bytes, including the Parameter Tag, Parameter Length, and Parameter
   Value fields. The Parameter Length does not include any padding
   bytes.

Parameter Value: variable-length.

   The Parameter Value field contains the actual information to be
   transferred in the parameter.

   The total length of a parameter (including Tag, Parameter Length and
   Value fields) MUST be a multiple of 4 bytes. If the length of the
   parameter is not a multiple of 4 bytes, the sender pads the
   Parameter at the end (i.e., after the Parameter Value field) with
   all zero bytes. The length of the padding is NOT included in the
   parameter length field. A sender SHOULD NEVER pad with more than 3
   bytes. The receiver MUST ignore the padding bytes.

3.3 Transfer Messages

The following section describes the Transfer messages and parameter
contents.

3.3.1 Payload Data Message (DATA)

The DATA message contains the SS7 MTP3-User protocol data, which is an
MTP-TRANSFER primitive, including the complete MTP3 Routing Label. The
Data message contains the following variable length parameters:

     Network Appearance       Optional
     Protocol Data 1 or 2     Mandatory

The following format MUST be used for the Data Message:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1            |          Length = 8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Network Appearance*                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 3            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                        Protocol Data                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Network Appearance: 32-bits (unsigned integer)

   The optional Network Appearance parameter identifies the SS7 network
   context for the message, for the purposes of logically separating
   the signalling traffic between the SG and the Application Server
   Process over a common SCTP Association.  An example is where an SG
   is logically partitioned to appear as an element in four different
   national SS7 networks.

   In a Data message, the Network Appearance implicitly defines the SS7
   Point Code format used, the SS7 Network Indicator value, and the
   MTP3 and possibly the MTP3-User protocol type/variant/version used
   within the SS7 network partition.  Where an SG operates in the
   context of a single SS7 network, or individual SCTP associations are
   dedicated to each SS7 network context, the Network Appearance
   parameter is not required.

   The Network Appearance parameter value is of local significance
   only, coordinated between the SG and ASP. Therefore, in the case
   where an ASP is connected to more than one SG, the same SS7 network
   context may be identified by different Network Appearances depending
   over which SG a message is being transmitted/received.

   Where the optional Network Appearance parameter is present, it must
   be the first parameter in the message as it defines the format of
   the Protocol Data field.

Protocol Data 1 or 2: variable length

   One of two possible Protocol Data parameters are included in a DATA
   message: Protocol Data 1 or Protocol Data 2.

   The Protocol Data 1 parameter contains the original SS7 MTP3
   message, including the Service Information Octet and Routing Label.

   The Protocol Data 1 parameter contains the following fields:

       Service Information Octet. Includes:
            Service Indicator,
            Network Indicator,
            and Spare/Priority codes

       Routing Label. Includes:
            Destination Point Code,
            Originating Point Code,
            And Signalling Link Selection Code (SLS)

       User Protocol Data.  Includes:
            MTP3-User protocol elements (e.g., ISUP, SCCP, or TUP
               parameters)

   The Protocol Data 2 parameter contains all the information in
   Protocol Data 1 as described above, plus the MTP2 Length Indicator
   octet.  The MTP2 Length Indicator (LI) octet appears before the SIO
   and Routing Label information.  The MTP2 Length Indicator octet is
   required for some national MTP variants that use the spare bits in
   the LI to carry additional information of interest to the MTP3 and
   MTP3-User (e.g., the Japan TTC standard use of LI spare bits to
   indicate message priority)

   The Payload Data format is as defined in the relevant MTP standards
   for the SS7 protocol being transported.  The format is either
   implicitly known or identified by the Network Appearance parameter.
   Note: In the SS7 Recommendations, the format of the messages and
   fields within the messages are based on bit transmission order.  In
   these recommendations the Least Significant Bit (LSB) of each field
   is positioned to the right.  For this document the received SS7
   fields are populated octet by octet as received into the 4-octet
   word as shown in the examples below.

   For the ANSI protocol example, the Protocol Data field format is
   shown below:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      SIO      |  DPC Member  |  DPC Cluster  |  DPC Network   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  OPC Member  |  OPC Cluster  |  OPC Network   |      SLS      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                        Protocol Data                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |MSB---------------------------------------------------------LSB|

   Within each octet the Least Significant Bit (LSB) per the SS7
   Recommendations is to the right (e.g., bit 7 of SIO is the LSB).

   For the ITU international protocol example, the Protocol Data field
   is shown below.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |      SIO      | DPC     | DPC |OPC| DPC | DPC |   OPC       |@|
    |               | Region *| SP *|SP*|Zone*| reg.|  Region    *| |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  SLS  | OPC |$|      Protocol                                 |
    |      *| SP *| |        Data                                   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    * marks LSB of each field;  @ = OPC SP MSB;  $ = OPC region MSB

3.4 SS7 Signalling Network Management (SSNM) Messages

3.4.1 Destination Unavailable (DUNA)

The DUNA message is sent from the SG to all concerned ASPs to indicate
that the SG has determined that one or more SS7 destinations are
unreachable.  It is also sent in response to a message from the ASP to
an unreachable SS7 destination.  As an implementation option the SG may
suppress the sending of subsequent "response" DUNAs regarding a certain
unreachable SS7 destination for a certain period in order to give the
remote side time to react. The MTP3-User at the ASP is expected to stop
traffic to the affected destination through the SG initiating the DUNA
as per the defined MTP3-User procedures.

The DUNA message contains the following parameters:

     Network Appearance      Optional
     Affected Destinations   Mandatory
     Info String             Optional

The format for DUNA Message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1            |           Length =8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Network Appearance*                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 5            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Mask      |                 Affected DPC 1                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                              ...                              /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask      |                 Affected DPC n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Tag = 4           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Network Appearance: 32-bit unsigned integer

   See Section 3.3.1

Affected Destinations: n x 32-bits

   The Affected Destinations parameter contains up to sixteen Affected
   Destination Point Code fields, each a three-octet parameter to allow
   for 14-, 16- and 24-bit binary formatted SS7 Point Codes.  Affected
   Point Codes that are less than 24-bits, are padded on the left to
   the 24-bit boundary.  The encoding is shown below for ANSI and ITU
   Point Code examples.

ANSI 24-bit Point Code:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |    Network    |    Cluster    |     Member    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      |MSB-----------------------------------------LSB|

   ITU 14-bit Point Code:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |0 0 0 0 0 0 0 0 0 0|Zone |     Region    | SP  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                           |MSB--------------------LSB|

   It is optional to send an Affected Destinations parameter with more
   than one Affected DPC but it is mandatory to receive and process it.
   All the Affected DPCs included must be within the same Network
   Appearance.  Including multiple Affected DPCs may be useful when
   reception of an MTP3 management message or a linkset event
   simultaneously affects the availability status of a list of
   destinations at an SG.

Mask: 8-bits (unsigned integer)

   The Mask field associated with each Affected DPC in the Affected
   Destinations parameter, used to identify a contiguous range of
   Affected Destination Point Codes, independent of the point code
   format.  Identifying a contiguous range of Affected DPCs may be
   useful when reception of an MTP3 management message or a linkset
   event simultaneously affects the availability status of a series of
   destinations at an SG.  For example, if all DPCs in an ANSI cluster
   are determined to be unavailable due to local linkset
   unavailability, the DUNA could identify potentially 256 Affected
   DPCs in a single Affected DPC field.

   The Mask parameter represents a bit mask that can be applied to the
   related Affected DPC field.  The bit mask identifies how many bits
   of the Affected DPC field are significant and which are effectively
   "wildcarded".  For example, a mask of "8" indicates that the least
   significant eight bits of the DPC is "wildcarded".  For an ANSI 24-
   bit Affected DPC, this is equivalent to signalling that all DPCs in
   an ANSI Cluster are unavailable.  A mask of "3" indicates that the
   least significant three bits of the DPC is "wildcarded".  For a 14-
   bit ITU Affected DPC, this is equivalent to signaling that an ITU
   Region is unavailable. A mask value equal to the number of bits in
   the DPC indicates that the entire network appearance is affected 
   this is used to indicate network isolation to the ASP.

Info String: variable length

   The optional INFO String parameter can carry any 8-bit ASCII
   character string along with the message.  Length of the INFO
   String parameter is from 0 to 255 characters.  No procedures are
   presently identified for its use but the INFO String MAY be used by
   Operators to identify in text form the location reflected by the
   Affected DPC for debugging purposes.

3.4.2 Destination Available (DAVA)

The DAVA message is sent from the SG to all concerned ASPs to indicate
that the SG has determined that one or more SS7 destinations are now
reachable (and not restricted), or in response to a DAUD message if
appropriate. The ASP MTP3-User protocol is allowed to resume traffic to
the affected destination through the SG initiating the DUNA.

The DAVA message contains the following parameters:

     Network Appearance       Optional
     Affected Destinations    Mandatory
     Info String              Optional

The format and description of the Network Appearance, Affected
Destinations and Info String parameters is the same as for the DUNA
message (See Section 3.4.1.)

3.4.3 Destination State Audit (DAUD)

The DAUD message can be sent from the ASP to the SG to audit the
availability/congestion state of SS7 routes to one or more affected
destinations.

The DAUD message contains the following parameters:

     Network Appearance      Optional
     Affected Destinations   Mandatory
     Info String             Optional

The format and description of DAUD Message parameters is the same as
for the DUNA message (See Section 3.4.1.)

3.4.4 SS7 Network Congestion (SCON)

The SCON message can be sent from the SG to all concerned ASPs to
indicate congestion in the SS7 network to one or more destinations, or

to an ASP in response to a DATA or DAUD message as appropriate.  For
some MTP protocol variants (e.g., ANSI MTP) the SCON may be sent when
the SS7 congestion level changes.  The SCON message MAY also be sent
from the M3UA of an ASP to an M3UA peer indicating that the M3UA or the
ASP is congested.

The SCON message contains the following parameters:

     Network Appearance       Optional
     Affected Destinations    Mandatory
     Concerned Destination    Optional     Congestion Indications
Optional
     Info String              Optional

The format for SCON Message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1            |           Length =8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Network Appearance*                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 5            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Mask     |                 Affected DPC 1                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                              ...                              /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Mask     |                 Affected DPC n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 15           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    reserved   |                 Concerned DPC                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 14           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Reserved                    |  Cong. Level* |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                         INFO String*                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format and description of the Network Appearance, Affected
Destinations, and Info String parameters is the same as for the DUNA
message (See Section 3.4.1.)

The Affected Destinations parameter can be used to indicate congestion
of multiple destinations or ranges of destinations.  However, an SCON
MUST not be delayed in order to "collect" individual congested
destinations into a single SCON as any delay might affect the timing of
congestion indications to the M3UA Users.  One use for including a
range of Congested DPCs is when the SG supports an ANSI cluster route
set to the SS7 network that becomes congested due to outgoing link set
congestion.

Concerned Destination: 32-bits

   The optional Concerned Destination parameter is only used if the
   SCON is sent from an ASP to the SG. It contains the point code of
   the originator of the message that triggered the SCON. The Concerned
   Destination parameter contains one Concerned Destination Point Code
   field, a three-octet parameter to allow for 14-, 16- and 24-bit
   binary formatted SS7 Point Codes.  A Concerned Point Code that is
   less than 24-bits, is padded on the left to the 24-bit boundary. The
   SG sends a Transfer Controlled Message to the Concerned Point Code
   using the single Affected DPC contained in the SCON to populate the
   (affected) Destination field of the TFC message. Normally the
   Affected DPC will be equal to the point code of the ASP.

Congested Indications: 32-bits

   The optional Congestion Indications parameter contains a Congestion
   Level field.  This optional parameter is used to communicate
   congestion levels in national MTP networks with multiple congestion
   thresholds, such as in ANSI MTP3.  For MTP congestion methods
   without multiple congestion levels (e.g., the ITU international
   method) the parameter is not included.

Congestion Level field: 8-bits (unsigned integer)

   The Congestion Level field, associated with all of the Affected
   DPC(s) in the Affected Destinations parameter, contains one of the
   Following values:

         0     No Congestion or Undefined
         1     Congestion Level 1
         2     Congestion Level 2
         3     Congestion Level 3

   The congestion levels are defined in the congestion method in the
   appropriate national MTP recommendations [14,15].

3.4.5 Destination User Part Unavailable (DUPU)

The DUPU message is used by an SG to inform an ASP that a remote peer
MTP3-User Part (e.g., ISUP or SCCP) at an SS7 node is unavailable.

The DUPU message contains the following parameters:

     Network Appearance       Optional
     Affected Destinations    Mandatory
     User/Cause               Mandatory
     Info String              Optional

The format for DUPU Message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Network Appearance*                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 5            |          Length = 8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Mask = 0    |                  Affected DPC                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 9            |          Length = 8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Cause             |            User               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

User/Cause: 32-bits

   The Unavailability Cause and MTP3-User Identity fields, associated
   with the Affected DPC in the Affected Destinations parameter, are
   encoded as follows:

Unavailability Cause field: 16-bits (unsigned integer)

   The Unavailability Cause parameter provides the reason for the
   unavailability of the MTP3-User.  The valid values for the
   Unavailability Cause parameter are shown in the following table.
   The values agree with those provided in the SS7 MTP3 User Part
   Unavailable message.  Depending on the MTP3 protocol used in the
   network appearance, additional values may be used - the
   specification of the relevant MTP3 protocol variant/version
   recommendation is definitive.

         0         Unknown
         1         Unequipped Remote User
         2         Inaccessible Remote User

MTP3-User Identity field: 16-bits (unsigned integer)

   The MTP3-User Identity describes the specific MTP3-User that is
   unavailable (e.g., ISUP, SCCP, ...).  Some of the valid values for
   the MTP3-User Identity are shown below.  The values agree with those
   provided in the SS7 MTP3 User Part Unavailable message and Service
   Indicator.  Depending on the MTP3 protocol variant/version used in
   the network appearance, additional values may be used.  The relevant
   MTP3 protocol variant/version recommendation is definitive.

       0 to 2       Reserved
          3         SCCP
          4         TUP
          5         ISUP
       6 to 8       Reserved
          9         Broadband ISUP
         10        Satellite ISUP

The format and description of the Affected Destinations parameter is
the same as for the DUNA message (See Section 3.4.1.) except that the
Mask field is not used and only a single Affected DPC is included.
Ranges and lists of Affected DPCs cannot be signaled in a DUPU, but
this is consistent with UPU operation in the SS7 network. The Affected
Destinations parameter in an MTP3 User Part Unavailable message (UPU)
received by an SG from the SS7 network contains only one destination.

The format and description of the Network Appearance parameter and Info String
parameters is the same as for the DUNA message (See Section 3.4.1.).

3.4.6 Destination Restricted (DRST)

The DRST message is optionally sent from the SG to all concerned ASPs
to indicate that the SG has determined that one or more SS7
destinations are now restricted, or in response to a DAUD message if
appropriate. The M3UA at the ASP is present, it must expected to send traffic to the
affected destination via an alternate SG of equal priority, but only if
such an alternate route exists and is available. If the affected
destination is currently considered unavailable by the ASP, traffic to
the affected destination through the SG initiating the DRST should be
resumed.

This message is optional for the first parameter SG to send and optional for the ASP to
process. It is for use in the "STP" case described in Section 1.4.2.

The DRST message as it defines contains the following parameters:

     Network Appearance       Optional
     Affected Destinations    Mandatory
     Info String              Optional

The format and description of the Protocol Data field.

Protocol Data: variable length Network Appearance, Affected
Destinations and Info String parameters is the same as for the DUNA
message (See Section 3.4.1.)

3.5 Application Server Process Maintenance (ASPM) Messages

3.5.1 ASP Up (ASPUP)

The Protocol Data field ASP UP (ASPUP) message is used to indicate to a remote M3UA peer
that the Adaptation layer is ready to receive SSNM or ASPM management
messages for all Routing Keys that the ASP is configured to serve.

The ASPUP message contains the SS7 MTP3-User application
   message, including following parameters:

     INFO String                   Optional

The format for ASPUP Message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format and description of the optional Info String parameter is the Service Information Octet and Routing Label.
same as for the DUNA message (See Section 3.4.1.)

3.5.2 ASP Up Ack

The Protocol Data parameter ASP UP Ack message is used to acknowledge an ASP-Up message
received from a  remote M3UA peer.

The ASPUP Ack message contains the following fields:

       Service Information Octet. Includes:
            Service Indicator,
            Network Indicator,
            and Spare/Priority codes

       Routing Label. Includes:
            Destination Point Code,
            Originating Point Code,
            And Signalling Link Selection Code (SLS)

       User Protocol Data.  Includes MTP3-User protocol elements:
            ISUP, SCCP, or TUP parameters parameters:

     INFO String (optional)

The format for ASPUP Ack Message parameters is as defined in follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag =4             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format and description of the relevant MTP standards optional Info String parameter is the
same as for the SS7
   protocol being transported. DUNA message (See Section 3.4.1.)

3.5.3 ASP Down (ASPDN)

The format ASP Down (ASPDN) message is either implicitly known
   or identified by the Network Appearance parameter.

   For used to indicate to a remote M3UA peer
that the ANSI protocol example, adaptation layer is NOT ready to receive traffic or
maintenance messages.

The ASPDN message contains the Protocol Data field following parameters:

     Reason         Mandatory
     INFO String    Optional

The format for the ASPDN message parameters is
   shown below: as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      SIO      |  DPC Network 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  DPC Cluster           Tag = 10            |  DPC Member            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  OPC Network                              Reason                           |  OPC Cluster
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  OPC Member            Tag =4             |      SLS            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                        Protocol Data                         INFO String*                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |MSB---------------------------------------------------------LSB|

   For

The format and description of the ITU international protocol example, optional Info String parameter is the Protocol Data field
same as for the DUNA message (See Section 3.4.1.)

Reason: 32-bit (unsigned integer)

   The Reason parameter indicates the reason that the remote M3UA
   adaptation layer is unavailable.  The valid values for Reason are
   shown below. in the following table.

         0       Unspecified
         1       User Unavailable
         2       Management Blocking

3.5.4 ASP Down Ack

The ASP Down Ack message is used to acknowledge an ASP-Down message
received from a remote M3UA peer, or to reply to an ASPM message from
an ASP which is locked out for management reasons.

The ASP Down Ack message contains the following parameters:

     Reason          Mandatory
     INFO String     Optional

The format for the ASPDN Ack message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      SIO      | DPC |      DPC      | DPC | OPC |     OPC     |
   |               |Zone |     Region    | SP  |Zone           Tag = 10            |    Region            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |*| OPC |  SLS
   |                              Reason                           |
   |*| SP
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |            Length             |
   +-+-+-+-+-+-+-+-+                                               +
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                        Protocol Data                         INFO String*                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |MSB---------------------------------------------------------LSB|

       * LSB of OPC Region

3.4 SS7 Signalling Network Management (SSNM) Messages

3.4.1 Destination Unavailable (DUNA)

The format and description of the optional Info String parameter is the
same as for the DUNA message (See Section 3.4.1.)

The format of the Reason parameter is the same as for the ASP-Down
message. (See Section 3.4.3)

3.5.5 Registration Request (REG REQ)

The REG REQ message is sent from the SG to all concerned ASPs by an ASP to indicate to a remote M3UA peer
that the SG has determined that it wishes to register one or more SS7 destinations are
unreachable.  It is also sent in response to a message from given Routing Key with the ASP to

remote peer.  Typically, an unreachable SS7 destination.  The MTP3-User at the ASP is expected would send this message to stop traffic an SGP, and
expects to the affected destination through the SG initiating
the DUNA as per the defined MTP3-User procedures. receive a REG RSP in return with an associated Routing
Context value.

The DUNA REG REQ message contains the following parameters:

     Network Appearance      Optional
     Affected Destinations

     Routing Key           Mandatory
     Info String             Optional

The format for DUNA Message parameters the REG REQ message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1            |           Length =8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Network Appearance*                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 5 16           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask      |                 Affected DPC
   \                                                               \
   /                         Routing Key 1                |                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                              ...                              /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask      |                 Affected DPC n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4 16           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         Routing Key n                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Network Appearance: 32-bit unsigned integer

Routing Key: variable length

   The optional Network Appearance Routing Key parameter identifies the SS7 network
   context for the message, for the purposes of logically separating
   the signalling traffic between the SG and the Application Server
   Process over a common SCTP Association.  An example is where an SG is logically partitioned to appear as an element in four different
   national SS7 networks.

   In an SSNM message, the Network Appearance parameter defines the
   format of the Affected DPC(s) in the Affected Destination parameter. mandatory. The DPC point code length (e.g., 14-, 16-, or 24-bit) and sub-field
   definitions (e.g., ANSI 24-bit network/cluster/member, ITU-
   international 14-bit zone/region/signal_point, many national field
   variants, ...) are fixed within a particular Network Appearance.
   Where an SG operates in sender of this message
   expects that the context receiver of this message will create a single SS7 network, or
   individual SCTP associations are dedicated Routing
   Key entry and assign a unique Routing Context value to each SS7 network
   context, it, if the Network Appearance
   Routing Key entry does not already exist.

   The Routing Key parameter may be present multiple times in the same
   message. This is not required and used to allow the
   format registration of the Affected DPC(s) is understood implicitly. multiple Routing
   Keys in a single message.

The format of the Routing Key parameter is as follows.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Local-RK-Identifier                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Destination Point Code                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Network Appearance parameter (optional)                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       SI (optional)                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         SSN (optional)                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Origination Point Code List (optional)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Circuit Range List (optional)               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Local-RK-Identifier: 32-bit integer

   The mandatory Local-RK-Identifier field is an integer, the
   values used are of local significance only, coordinated between to uniquely identify
   the
   SG and ASP.

   Where registration request. The Identifier value is assigned by the optional Network Appearance parameter
   ASP, and is present, it must
   be used to correlate the first parameter response in the an REG RSP message as it defines the format of
   the Affected DPCs in
   with the Affected Destination parameter.

Affected Destinations: n x 32-bits original registration request. The Affected Destinations parameter contains up to sixteen Affected
   Destination Point Code fields, each a three-octet parameter to allow
   for 14-, 16- and 24-bit binary formatted SS7 Point Codes.  Affected
   Point Codes that are less than 24-bits, are padded on the left to Identifier value must
   remain unique until the 24-bit boundary. REG RSP is received.

   The encoding format of the Local-RK-Identifier field is shown below for ANSI and ITU
   Point Code examples.

   ANSI 24-bit Point Code: as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Mask           Tag = 19            |    Network         Length = 8            |    Cluster
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Member                  Local-RK-Identifier value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      |MSB-----------------------------------------LSB|

   ITU 14-bit

Destination Point Code:

   The Destination Point Code parameter is mandatory, and identifies
   the Destination Point Code of incoming SS7 traffic for which the ASP
   is registering.  The format is the same as described for the
   Affected Destination parameter in the DUNA Message (See Section
   3.4.1). Its format is:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 20            |         Length = 8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask      |0 0 0 = 0   |            Destination Point Code             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Network Appearance:

   The optional Network Appearance parameter field identifies the SS7
   Network context for the Routing Key, and has the same format as in
   the Data message (See Section 3.3.1). Its format is:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 0|Zone 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Region            Tag = 1            | SP         Length = 8            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                           |MSB--------------------LSB|

   It is optional to send an Affected Destinations parameter with more
   than one Affected DPC but it is mandatory to receive and process it.
   All the Affected DPCs included must be within the same
   |                     Network
   Appearance.  Including multiple Affected DPCs may be useful when
   reception of an MTP3 management message or a linkset event
   simultaneously affects the availability status of a list of
   destinations at an SG.

Mask: 8-bits (unsigned integer)

   The Mask field associated with each Affected DPC Appearance                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Service Indicators (SI): n X 8-bit integers

   The SI field contains one or more Service Indicators from the values
   as described in the Affected
   Destinations parameter, used to identify a contiguous range of
   Affected Destination Point Codes, independent MTP3-User Identity field of the point code
   format.  Identifying a contiguous range of Affected DPCs may be
   useful when reception DUPU Message.
   The absence of an MTP3 management message or a linkset
   event simultaneously affects the availability status of a series of
   destinations at an SG.  For example, if all DPCs SI parameter in an ANSI cluster
   are determined to be unavailable due to local linkset
   unavailability, the DUNA could identify potentially 256 Affected
   DPCs in a single Affected DPC field.

   The Mask parameter represents a bit mask that can be applied to Routing Key indicates the
   related Affected DPC field.  The bit mask identifies how many bits use
   of the Affected DPC field are significant and which are effectively
   "wildcarded".  For example, any SI values, excluding of course MTP management.  Where an SI
   parameter does not contain a mask multiple of "8" indicates that four SIs, the last
   eight bits parameter is
   padded out to 32-byte alignment.  An SI value of the DPC zero is "wildcarded".  For an ANSI 24-bit Affected
   DPC, this not valid
   in M3UA.  The SI format is:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 21            |         Length = var.         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      SI #1    |     SI #2     |    SI #3      |    SI #4      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                              ...                              /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      SI #n    |             0 Padding, if necessary           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Subsystem Numbers (SSN): n X 8-bit integers

   The optional SSN field contains one or more SCCP subsystem numbers,
   and is equivalent to signalling that all DPCs used in conjunction with an ANSI
   Cluster are unavailable.  A mask SI values of "3" indicates that the last
   three bits 3 (i.e., SCCP) only.
   Where an SSN parameter does not contain a multiple of four SSNs, the DPC is "wildcarded".  For a 14-bit ITU Affected
   DPC, this is equivalent to signaling that an ITU Region
   parameter is
   unavailable. A mask value equal padded out to the 32-byte alignment. The subsystem number of bits in the DPC
   indicates that
   values associated are defined by the entire local network appearance operator, and
   typically follow ITU-T Recommendation Q.713.  An SSN value of zero
   is affected - not valid in M3UA.  The format of this field is
   used to indicate network isolation to the ASP.

Info String: variable length as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 22            |         Length = var.         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     SSN #1    |    SSN #2     |   SSN #3      |   SSN #4      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                              ...                              /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     SSN #n    |             0 Padding, if necessary           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

OPC List:

   The optional INFO String Originating Point Code List parameter can carry any meaningful 8-BIT
   ASCII character string along with contains one or more SS7
   OPC entries, and its format is the message.  Length of same as the INFO
   String parameter is from Destination Point
   Code parameter.

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 23            |         Length = var.         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask = 0   |          Origination Point Code #1            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask = 0   |          Origination Point Code #2            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                              ...                              /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask = 0 to 255 characters.  No procedures are
   presently   |          Origination Point Code #n            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Circuit Range:

   An ISUP controlled circuit is uniquely identified for its use but the INFO String may be used by
   Operators to identify in text form the location reflected by the
   Affected SS7 OPC,
   DPC for debugging purposes.

3.4.2 Destination Available (DAVA)

The DAVA message is sent from and CIC value.  For the SG to all concerned ASPs to indicate
that purposes of identifying Circuit Ranges
   in an M3UA Routing Key, the SG has determined that optional Circuit Range parameter
   includes one or more SS7 destinations are now
reachable, or in response to a DAUD message if appropriate. circuit ranges, each identified by an OPC and
   Upper/Lower CIC value.  The ASP
MTP3-User protocol DPC is expected to resume traffic to the affected
destination through the SG initiating the DUNA.

The DAVA message contains the following parameters:

     Network Appearance       Optional
     Affected Destinations    Mandatory
     Info String              Optional

The format implicit as it is mandatory and description
   already included in the DPC parameter of the Network Appearance, Affected
Destinations and Info String parameters Routing Key.  The
   Origination Point Code is encoded the same as for the DUNA
message (See Section 3.4.1.)

3.4.3 Destination State Audit (DAUD)

The DAUD message can be sent from the ASP to the SG to audit Point
   Code parameter, while the
availability/congestion state of SS7 routes to one or more affected
destinations. CIC values are 16-bit integers.

   The Circuit Range format is as follows:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 24            |         Length = var.         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask = 0   |          Origination Point Code #1            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Lower CIC Value #1      |      Upper CIC Value #1       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask = 0   |          Origination Point Code #2            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Lower CIC Value #2      |      Upper CIC Value #2       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                              ...                              /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Mask = 0   |          Origination Point Code #n            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Lower CIC Value #n      |      Upper CIC Value #n       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.5.6 Registration Response (REG RSP)

The DAUD REG RSP message contains the following parameters:

     Network Appearance      Optional
     Affected Destinations   Mandatory
     Info String             Optional

The format and description of DAUD Message parameters is the same used as
for the DUNA message (See Section 3.4.1.)

3.4.4 SS7 Network Congestion (SCON)

The SCON message can be sent from the SG to all concerned ASPs to
indicate congestion in the SS7 network to one or more destinations, or
to an ASP in a response to a DATA or DAUD message as appropriate.  For
some MTP protocol variants (e.g., ANSI MTP) the SCON may be sent when the SS7 congestion level changes.  The SCON REG REQ message MAY also be sent from the a
remote M3UA peer.  It contains indications of an ASP success/failure for
registration requests and returns a unique Routing Context value for
successful registration requests, to an M3UA peer indicating that the be used in subsequent M3UA or the
ASP is congested. Traffic
Management protocol.

The SCON REG RSP message contains the following parameters:

     Network Appearance       Optional
     Affected Destinations

     Registration Results   Mandatory
     Congestion Indications   Optional
     Info String              Optional

The format for SCON Message parameters the REG RSP message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1 25           |         Length =8 = var.         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Network Appearance*                    Registration Result 1                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                              ...                              /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag =                    Registration Result n                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Registration Results:

   The Registration Results parameter contains one or more results,
   each containing the registration status for a single Routing Key in
   an REG REQ message.  The number of results in a single REG RSP
   message MAY match the number of Routing Key parameters found in the
   corresponding REG REQ message.  The format of each result is as
   follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Mask     |                 Affected DPC 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                              ...                              /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Mask     |                 Affected DPC n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 14           |             Length                  Local-RK-Identifier value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Reserved                    |  Cong. Level*                      Registration Status                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |             Length                        Routing Context                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                         INFO String*                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Local-RK-Identifier: 32-bit integer

   The format and description of the Network Appearance, Affected
Destinations, and Info String parameters is Local-RK-Identifier contains the same value as for found in the DUNA
message (See Section 3.4.1.)

The Affected Destinations
   matching Routing Key parameter can be used to indicate congestion
of multiple destinations or ranges of destinations.  However, an SCON
MUST not be delayed found in order to "collect" individual congested
destinations into a single SCON as any delay might affect the timing of
congestion indications to REG Req message.

Registration Status: 32-bit integer

   The Registration Result Status field indicates the M3UA Users.  One use success or the
   reason for including a
range failure of Congested DPCs is when a registration request.

   Its values may be:

        0           Successfully Registered
        1           Error - Unknown
        2           Error - Invalid DPC
        3           Error - Invalid Network Appearance
        4           Error - Invalid Routing Key
        5           Error - Permission Denied
        6           Error - Overlapping (Non-unique) Routing Key
        7           Error - Routing Key not Provisioned
        8           Error - Insufficient Resources

Routing Context: 32-bit integer

   The Routing Context field contains the SG supports an ANSI cluster route Routing Context value for the
   associated Routing Key if the registration was successful. It is set
   to "0" if the SS7 network registration was not successful.

3.5.7 De-Registration Request (DEREG REQ)

The DEREG REQ message is sent by an ASP to indicate to a remote M3UA
peer that becomes congested due it wishes to outgoing link set
congestion.

Congested Indications: 32-bits

   The optional Congestion Indications parameter contains de-register a Congestion
   Level field.  This optional parameter is used given Routing Key. Typically, an
ASP would send this message to communicate
   congestion levels an SGP, and expects to receive a DEREG
RSP in national MTP networks return with multiple congestion
   thresholds, such as in ANSI MTP3.  For MTP congestion methods
   without multiple congestion levels (e.g., the ITU international
   method) the parameter is not included.

Congestion Level field: 8-bits (unsigned integer)

   The Congestion Level field, associated with all of the Affected
   DPC(s) in the Affected Destinations parameter, Routing Context value.

The DEREG REQ message contains one of the
   Following values: following parameters:

     Routing Context       Mandatory

The format for the DEREG REQ message is as follows:

    0     No Congestion or Undefined                   1     Congestion Level                   2                   3
    0 1 2     Congestion Level 3 4 5 6 7 8 9 0 1 2 3     Congestion Level 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 6            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Routing Context: n X 32-bit integers

   The congestion levels are defined in Routing Context parameter contains (a list of) integers indexing
   the congestion method in Application Server traffic that the
   appropriate national MTP recommendations [14,15].

3.4.5 Destination User Part Unavailable (DUPU) sending ASP is currently
   registered to receive from the SG but now wishes to deregister.

3.5.8 De-Registration Response (DEREG RSP)

The DUPU DEREG RSP message is used by an SG as a response to inform an ASP that the DEREG REQ message
from a remote peer
MTP3-User Part (e.g., ISUP or SCCP) at an SS7 node is unavailable. remote M3UA peer.

The DUPU DEREG RSP message contains the following parameters:

     Network Appearance       Optional
     Affected Destinations    Mandatory
     User/Cause

     De-registration Results    Mandatory
     Info String              Optional

The format for DUPU Message parameters the DEREG RSP message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 1            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Network Appearance*                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 5            |          Length = 8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Mask = 0    |                  Affected DPC                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 9 18           |           Length = 8           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Cause             |            User var        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |             Length                  De-Registration Result 1                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                              ...                              /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

User/Cause: 32-bits

   The Unavailability Cause and MTP3-User Identity fields, associated
   with the Affected DPC in the Affected Destinations parameter, are
   encoded as follows:

Unavailability Cause field: 16-bits (unsigned integer)
   |                  De-Registration Result n                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

De-Registration Results:

   The Unavailability Cause De-Registration Results parameter provides the reason for the
   unavailability of contains one or more results,
   each containing the MTP3-User.  The valid values de-registration status for the
   Unavailability Cause parameter are shown in the following table.
   The values agree with those provided a single Routing
   Context in the SS7 MTP3 User Part
   Unavailable a DEREG REQ message.  Depending on the MTP3 protocol used in the
   network appearance, additional values may be used - the
   specification of the relevant MTP3 protocol variant/version
   recommendation is definitive.

         0         Unknown
         1         Unequipped Remote User
         2         Inaccessible Remote User

MTP3-User Identity field: 16-bits (unsigned integer)  The MTP3-User Identity describes the specific MTP3-User that is
   unavailable (e.g., ISUP, SCCP, ...).  Some number of the valid values for
   the MTP3-User Identity are shown below.  The values agree with those
   provided results in the SS7 MTP3 User Part Unavailable a single
   DEREG RSP message and Service
   Indicator.  Depending on the MTP3 protocol variant/version used in MAY match the network appearance, additional values may be used. number of Routing Contexts found in
   the corresponding DEREG REQ message.  The relevant
   MTP3 protocol variant/version recommendation format of each result is definitive.
   as follows:

    0 to                   1                   2                   3
    0 1 2       Reserved 3         SCCP 4         TUP 5         ISUP 6 to 7 8       Reserved 9         Broadband ISUP
          10        Satellite ISUP 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Routing Context                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    De-Registration Status                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Routing Context: 32-bit integer

   The Affected Destinations parameter in a DUPU message differs from the
Affected Destinations parameter in the DUNA, DAVA, and DAUD in that the
Mask Routing Context field is not used and only a single Affected DPC is attached.
Ranges and lists contains the Routing Context value of Affected DPCs cannot be signaled, but this is
consistent with operation in the SS7 network. The Affected Destinations
parameter
   matching Routing Key to deregister, as found in an MTP3 User Part Unavailable message (UPU) received by an
SG from the SS7 network contains only one destination. DEREG Req.

De-Registration Status: 32-bit integer

   The format and description of De-Registration Result Status field indicates the Network Appearance and Info String
parameters is success or the same as
   reason for failure of the DUNA message (See Section 3.4.1.).

3.5 Application Server Process Maintenance (ASPM) Messages

3.5.1 de-registration.

   Its values may be:
        0           Successfully De-registered
        1           Error - Unknown
        2           Error - Invalid Routing Context
        3           Error - Permission Denied
        4           Error - Not Registered

3.5.5 ASP Up (ASPUP) Active (ASPAC)

The ASP UP (ASPUP) ASPAC message is used sent by an ASP to indicate to a remote M3UA peer
that the Adaptation layer it is Active and ready to receive  SSNM or ASPM management
messages process signalling traffic for all Routing Keys that a
particular Application Server.  The ASPAC affects only the ASP state
for the routing keys identified by the ASP is configured to serve. Routing Contexts, if present.

The ASPUP ASPAC message contains the following parameters:

     Traffic Mode Type     Mandatory
     Routing Context       Optional
     INFO String           Optional

The format for ASPUP Message parameters the ASPAC message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 11            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Traffic Mode Type                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 6            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 4              |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Traffic Mode Type: 32-bit (unsigned integer)

   The format and description of the optional Info String Traffic Mode Type parameter is identifies the
same as for traffic mode of
   operation of the DUNA message (See Section 3.4.1.)

3.5.2 ASP Up Ack

The ASP UP Ack message is used to acknowledge within an ASP-Up message
received from a  remote M3UA peer. AS. The ASPUP Ack message contains valid values for Type are
   shown in the following parameters:

     INFO String (optional)

The format for ASPUP Ack Message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 table.

         1         Over-ride
         2         Load-share
         3         Over-ride (Standby)
         4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag =4            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+         Load-share (Standby)
   Within a particular Routing Context, only one Traffic Mode Type
   can be used.  The format Over-ride value indicates that the ASP is
   operating in Over-ride mode, and description the ASP takes over all
   traffic in an Application Server (i.e., primary/back-up operation),
   over-riding any currently active ASPs in the AS.  In Load-share
   mode, the ASP will share in the traffic distribution with any other
   currently active ASPs.  The Standby versions of the optional Info String parameter Over-ride and
   Load-share Types indicate that the ASP is declaring itself ready to
   accept traffic but leaves it up to the
same sender as for to when the DUNA message (See Section 3.4.1.)

3.5.3 traffic
   is started.  Over-ride (Standby) indicates that the traffic sender
   continues to use the currently active ASP Down (ASPDN)

The until it can no longer
   send/receive traffic (i.e., the currently active ASP transitions to
   Down (ASPDN) message or Inactive).  At this point the sender MUST move the standby
   ASP to Active and commence traffic.  Load-share (Standby) is used similar
   - the sender continues to indicate load-share to a remote M3UA peer
that the adaptation layer current ASPs until it is not ready
   determined that there is insufficient resources in
   the Load-share group.  When there are insufficient ASPs, the sender
   MUST move the ASP to receive traffic or management
messages. Active.

Routing Context: n X 32-bit integers

   The ASPDN message optional Routing Context parameter contains (a list of) integers
   indexing the following parameters:

     Reason         Mandatory
     INFO String    Optional

The format for Application Server traffic that the ASPDN message parameters sending ASP is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 10            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Reason                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag =4             |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                         INFO String*                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format
   configured/registered to receive.

   There is one-to-one relationship between an index entry and description of an SG
   Routing Key or AS Name.  Because an AS can only appear in one
   Network Appearance, the optional Info String Network Appearance parameter is not required
   in the
same as ASPAC message.

   An Application Server Process may be configured to process traffic
   for more than one logical Application Server.  From the DUNA message (See Section 3.4.1.)

Reason: 32-bit (unsigned integer)

   The Reason parameter indicates the reason perspective
   of an ASP, a Routing Context defines a range of signalling traffic
   that the remote M3UA
   adaptation layer is unavailable.  The valid values for Reason are
   shown in the following table.

         0       Unspecified
         1       User Unavailable
         2       Management Blocking

3.5.4 ASP Down Ack

The ASP Down Ack message is used currently configured to acknowledge an ASP-Down message
received receive from a remote M3UA peer.

The ASP Down Ack message contains the following parameters:

     Reason          Mandatory
     INFO String     Optional

The format SG.  For
   example, an ASP could be configured to support call processing for the ASPDN Ack message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 10            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Reason                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                         INFO String*                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   multiple ranges of PSTN trunks and therefore receive related
   signalling traffic, identified by separate SS7 DPC/OPC/CIC_ranges.

The format and description of the optional Info String parameter is the
same as for the DUNA message (See Section 3.4.1.)

The format of the Reason parameter is the same as for the ASP-Down
message. (See Section 3.4.3)

3.5.5

3.5.6 ASP Active (ASPAC) Ack

The ASPAC Ack message is sent by an ASP to indicate used to acknowledge an ASP-Active message
received from a remote M3UA peer
that it peer.  In the case where an ASPAC (Over-
ride (standby)) or ASPAC (load-share (standby) is Active and ready to process signalling traffic for received, a
particular Application Server.  The ASPAC affects only second
ASPACK Ack is sent when the ASP state
for the routing keys identified by is moved to the Routing Contexts, if present. "Active" state from
"Active (Standby)".

The ASPAC Ack message contains the following parameters:

     Traffic Mode Type     Mandatory
     Routing Context       Optional
     INFO String           Optional

The format for the ASPAC Ack message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag = 11            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Traffic Mode Type                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag =6 = 6            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Traffic Mode Type: 32-bit (unsigned integer)

   The Traffic Mode Type parameter identifies the traffic mode of
   operation of the ASP within an AS. The valid values for Type are
   shown in the following table.

         1         Over-ride
         2         Load-share
         3         Over-ride (Standby)
         4         Load-share (Standby)

   Within a particular Routing Context, Over-ride and Load-share Types
   cannot be mixed.  The Over-ride value indicates that the ASP is
   operating in Over-ride mode, and the ASP wishes to take over all
   traffic in an Application Server (i.e., primary/back-up operation),
   over-riding any currently active ASP in the AS.  In Load-share mode,
   the ASP wishes to share in the traffic distribution with any other
   currently active ASPs.  The Standby versions of the Over-ride and
   Load-share Types indicate that the ASP is declaring itself ready to
   accept traffic but leaves it up to the sender as to when the traffic
   is started.  Over-ride (Standby) indicates that the traffic sender
   continues to use the currently active ASP until it can no longer
   send/receive traffic (i.e., the currently active ASP transitions to
   Down or Inactive).  At this point the sender may immediately move
   the ASP to Active

The format and commence traffic.  Load-share (Standby) is
   similar - the sender continues to load-share to the current ASPs
   until there it is determined that there is insufficient resources in description of the Load-share group.  When there optional Info String parameter is insufficient ASPs, the sender
   may immediately move
same as for the ASP to Active.

Routing Context: DUNA message (See Section 3.3.2.1.)

The optional format of the Traffic Mode Type and Routing Context parameter contains (a list of) 4-byte
   unsigned integers indexing parameters is
the Application Server traffic that same as for the
   sending ASP-Active message. (See Section 3.4.5).

3.5.7  ASP Inactive (ASPIA)

The ASPIA message is configured/registered sent by an ASP to receive.

   There indicate to a remote M3UA peer
that it is one-to-one relationship between an index entry and an SG
   Routing Key or AS Name.  Because no longer an AS can active ASP to be used from within a list of
ASPs.  The ASPIA affects only appear in one
   Network Appearance, the Network Appearance parameter is not required ASP state in the ASPAC message.

   An Application Server Process may be configured to process traffic Routing Keys
identified by the Routing Contexts, if present.

The ASPIA message contains the following parameters:

     Routing Context         Optional
     INFO String             Optional

The format for more than one logical Application Server.  From the perspective ASPIA message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 6            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format and description of an ASP, a the optional Routing Context defines a range of signalling traffic
   that and Info
String parameters is the same as for the ASPAC message (See Section
3.5.5.)

3.5.8 ASP Inactive Ack

The ASPIA Ack message is currently configured used to receive acknowledge an ASP-Inactive message
received from a remote M3UA peer.

The ASPIA Ack message contains the SG.  For
   example, an ASP could be configured to support call processing following parameters:

     Routing Context       Optional
     INFO String           Optional

The format for
   multiple ranges of PSTN trunks and therefore receive related
   signalling traffic, identified by separate SS7 DPC/OPC/CIC_ranges. the ASPIA Ack message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 6            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4            |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format and description of the optional Info String parameter is the
same as for the DUNA message (See Section 3.4.1.)

3.5.6 ASP Active Ack

The ASPAC Ack format of the Routing Context parameter is the same as for the ASP-
Inactive message. (See Section 3.5.7).

3.5.9 Heartbeat (BEAT)

The Heartbeat message is optionally used to acknowledge an ASP-Active message
received from a remote ensure that the M3UA peer. peers
are still available to each other.  It is recommended for use when the
M3UA runs over a transport layer other than the SCTP, which has its own
heartbeat.

The ASPAC Ack BEAT message contains the following parameters:

     Traffic Mode Type     Mandatory
     Routing Context       Optional
     INFO String

     Heatbeat Data         Optional

The format for the ASPAC Ack BEAT message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 11            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Traffic Mode Type                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 6            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4 8            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                       Heartbeat Data *                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format and description of the optional Info String Heartbeat Data parameter is contents are defined by the
same as sending node.
The Heartbeat Data could include, for the DUNA message (See Section 3.3.2.1.) example, a Heartbeat Sequence
Number and/or Timestamp.  The format receiver of the Traffic Mode Type and Routing Context parameters is
the same a Heartbeat message does not
process this field as for it is only of significance to the ASP-Active sender.  The
receiver MUST respond with a BEAT-Ack message. (See Section 3.4.5).

3.5.7  ASP Inactive (ASPIA)

3.5.10 Heartbeat Ack (Beat-Ack)

The ASPIA Heartbeat Ack message is sent by an ASP to indicate in response to a remote M3UA peer
that it received Heartbeat
message.  It includes all the parameters of the received Heartbeat
message, without any change.

3.6  Management Messages

3.6.1  Error (ERR)

The Error message is no longer processing signalling traffic within used to notify a particular
Application Server.  The ASPIA affects only the ASP state in peer of an error event associated
with an incoming message.  For example, the
Routing Keys identified by message type might be
unexpected given the Routing Contexts, if present. current state, or a parameter value might be
invalid.

The ASPIA ERR message contains the following parameters:

     Traffic Mode Type

     Error Code                 Mandatory
     Routing Context         Optional
     INFO String
     Diagnostic Information     Optional

The format for the ASPIA ERR message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 11 12           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Traffic Mode Type                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 6            |            Length                          Error Code                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 4 7            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                     Diagnostic Information*                   /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Traffic Mode Type: 32-bit

Error Code: 32-bits (unsigned integer)

   The Traffic Mode Type Error Code parameter identifies indicates the traffic mode of
   operation of reason for the ASP within an AS. Error Message.
   The valid values for Type are
   shown in Error parameter value can be one of the following table. values:

     1            Over-ride      Invalid Version
     2            Load-share

   Within a particular      Invalid Network Appearance
     3      Unsupported Message Class
     4      Unsupported Message Type
     5      Unsupported/Invalid Traffic Handling Mode
     6      Unexpected Message
     7      Protocol Error
     8      Invalid Routing Context, only one Context
     9      Invalid Stream Identifier
    10      Invalid Parameter Value

The "Invalid Version" error is sent if a message was received with an
invalid or unsupported version.  The Error message contains the

supported version in the Common header.  The Error message could
optionally provide the supported version in the Diagnostic Information
area.

The "Invalid Network Appearance" error is sent by a SG if an ASP sends
a message with an invalid (unconfigured) Network Appearance value.

The "Unsupported Message Class" error is sent if a message with an
unexpected or unsupported Message Class is received.

The "Unsupported Message Type" error is sent if a message with an
unexpected or unsupported Message Type can is received.

The "Unsupported/Invalid Traffic Handling Mode" error is sent by a SG
if an ASP sends an ASP Active with an unsupported Traffic Handling Mode
or a Traffic Handling mode that is inconsistent with the presently
configured mode for the Application Server.  An example would be used. a case
in which the SG did not support load-sharing.

The
   Over-ride value indicates "Unexpected Message" error MAY be sent if a defined and recognized
message is received that the ASP is operating not expected in Over-ride
   mode, the current state( in some
cases the ASP may optionally silently discard the message and will no longer handle traffic within not send
an Application Server
   (i.e., it Error).  For example, silent discard is now used by an ASP if it
received a backup Transfer message from an SG while it was in a primary/back-up arrangement). the Inactive
state.

The
   Load-share value indicates "Protocol Error" error is sent for any protocol anomaly(i.e.,
reception of a parameter that the ASP is operating in Load-share
   mode and will no longer share syntactically correct but unexpected
in the traffic distribution current situation.

The "Invalid Routing Context" error is sent by an SG if an Asp sends a
message with any
   other currently active ASPs.

   A node that receives an ASPIA invalid (unconfigured) Routing Context value.

The "Invalid Stream Identifier" error is sent if a message was received
on an unexpected SCTP stream (e.g., a MGMT message was received on a
stream other than "0").

The " Invalid Parameter Value " error is sent if a message was received
with an incorrect Type for invalid parameter value (e.g., a
   particular routing Context will respond DUPU message was received with
a Mask value other than "0").

Diagnostic Information: variable length

   When included, the optional Diagnostic information can be any
   information germane to the error condition, to assist in
   identification of the error condition.  In the case of an Error Message
   (Cause: Invalid
   Network Appearance, Traffic Handling Mode).

The format and description of the optional Mode, Routing Context and Info
String parameters is or
   Parameter Value, the Diagnostic information includes the received
   parameter.  In the other cases, the Diagnostic information may be
   the same as for first 40 bytes of the ASPAC message (See Section
3.5.5.)

3.5.8 ASP Inactive Ack offending message.

Error messages are not generated in response to other Error messages.

3.6.2 Notify (NTFY)

The ASPIA Ack Notify message is used to acknowledge provide an autonomous indication of M3UA
events to an ASP-Inactive message
received from a remote M3UA peer.

The ASPIA Ack NTFY message contains the following parameters:

     Traffic Mode Type

     Status Type/ID              Mandatory
     Routing Context            Optional
     INFO String                Optional

The format for the ASPIA Ack NTFY message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 11 13             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Traffic Mode        Status Type            |    Status Identification      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 6              |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 4              |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Status Type: 16-bits (unsigned integer)

   The format and description Status Type parameter identifies the type of the Notify message.
   The following are the valid Status Type values:

         1     Application Server State Change (AS-StateChange)
         2     Other

Status Information: 16-bits (unsigned integer)

   The Status Information parameter contains more detailed information
   for the notification, based on the value of the Status Type.

   If the Status Type is AS_State_Change the following Status
   Information values are used:

         1    reserved
         2    Application Server Inactive (AS-Inactive)
         3    Application Server Active (AS-Active)
         4    Application Server Pending (AS-Pending)

   These notifications are sent from an SG to an ASP upon a change in
   status of a particular Application Server. The value reflects the
   new state of the Application Server.

   If the Status Type is Other, then the following Status Information
   values are defined:

         1    Insufficient ASP resources active in AS
         2    Alternate ASP Active

These notifications are not based on the SG reporting the state change
of an ASP or AS.  In the Insufficent ASP Resources case, the SG is
indicating to an "Inactive" ASP(s) in the AS that another ASP is
required in order to handle the load of the optional Info String parameter is AS (Load-sharing mode).
For the
same as for Alternate ASP Active case, an ASP is informed when an alternate
ASP transitions to the DUNA message (See Section 3.4.1.) ASP-Active state in Over-ride mode.

The format and description of the Traffic Mode Type and optional Routing Context and Info
String parameters is the same as for the ASP-Inactive message. ASPAC message (See Section 3.5.7).

3.5.9 Heartbeat (BEAT)
3.4.6.)

4.0 Procedures

The Heartbeat message is optionally used to ensure that the M3UA peers
are still available to each other.  It is recommended for use when the M3UA runs over a transport layer needs to respond to various local primitives it receives
from other than the SCTP, which has its own
heartbeat.

The BEAT message contains the following parameters:

     Heatbeat Data         Optional

The format for the BEAT message is layers as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 8            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Heartbeat Data *                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The Heartbeat Data parameter contents are defined by the sending node.
The Heartbeat Data could include, for example, a Heartbeat Sequence
Number and/or Timestamp.  The receiver of a Heartbeat message does not
process this field well as the messages that it is only of significance to receives from the sender.  The
receiver MUST respond with a BEAT-Ack message.

3.5.10 Heartbeat Ack (Beat-Ack)

The Heartbeat Ack message is sent
peer M3UA layer.  This section describes the M3UA procedures in
response to a received Heartbeat
message.  It includes all these events.

4.1 Procedures to support the parameters services of the received Heartbeat
message, without any change.

3.6  Management Messages

3.6.1  Error (ERR)

The Error message is used to notify a peer M3UA layer

4.1.1 Receipt of primitives from the M3UA-User

On receiving an error event associated
with MTP-Transfer request primitive from an incoming message.  For example, upper layer, or
the message type might be
unexpected given nodal inter-working function at an SG, the current state, or M3UA layer sends a parameter value might be
invalid.

The ERR
corresponding DATA message contains the following parameters:

     Error Code                 Mandatory
     Diagnostic Information     Optional (see Section 3) to its M3UA peer.  The format for M3UA
peer receiving the ERR Data message is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 12           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Error Code                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Tag = 7            |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                     Diagnostic Information*                   /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Error Code: 32-bits (unsigned integer) sends an MTP-Transfer indication
primitive to the upper layer.

The Error Code parameter indicates M3UA message distribution function (see Section 1.4.2.1) determines
the reason for Application Server (AS) based on comparing the Error Message.
   The Error parameter value can information in the
MTP-Transfer request primitive with a provisioned Routing Key.

>From the list of ASPs within the AS table, an Active ASP is selected
and a DATA message is constructed and issued on the corresponding SCTP
Association.  If more than one ASP is active (i.e., traffic is to be
load-shared across all the active ASPs), one of the following values:

     1      Invalid Version
     2      Invalid Network Appearance
     3      Unsupported Message Type
     4      Invalid Message Type
     5      Invalid Traffic Handling Mode
     6      Unexpected Message
     7      Protocol Error
     8      Invalid Routing Context

Diagnostic Information: variable length

   When included, active ASPs from
the optional Diagnostic information can list is selected.  The selection algorithm is implementation
dependent but could, for example, be any
   information germane to round-robin or based on, for
example, the error condition, to assist in
   identification SLS or ISUP CIC.  The appropriate selection algorithm must
be chosen carefully as it is dependent on application assumptions and
understanding of the error condition.  In the case degree of an Invalid
   Network Appearance, Traffic Handling Mode or Routing Context, state coordination between the
   Diagnostic information includes active
ASPs in the received parameter. AS.

In addition, the
   other cases, the Diagnostic information may message needs to be sent on the first 40 bytes appropriate SCTP
stream, again taking care to meet the message sequencing needs of the offending message.

   In
signalling application.

When there is no Routing Key match, or only a partial match, for an
incoming SS7 message, a default treatment must be specified.  Possible
solutions are to provide a default Application Server at the case of SG that
directs all unallocated traffic to a (set of) default ASP(s), or to
drop the message and provide a notification to management in an Invalid Version Error Code, M-Error
indication primitive.  The treatment of unallocated traffic is
implementation dependent.

4.1.2 Receipt of primitives from the Layer Management

On receiving primitives from the Common Header
   contains local Layer Management, the supported Version.

Error messages are not generated in M3UA layer
will take the requested action and provide an appropriate  response
primitive to other Error messages.

3.6.2 Notify (NTFY) Layer Management.

An M-SCTP ESTABLISH request from Layer Management at an ASP or IPSP
will initiate the establishment of an SCTP association.  The Notify message used M3UA layer
will attempt to provide establish an autonomous indication of SCTP association with the remote M3UA
events peer
at by sending an SCTP-Associate primitive to the local SCTP layer.

When an SCTP association has been successfully established, the SCTP
will send an SCTP-Communication Up notification to the local M3UA peer.

The NTFY message contains
layer.  At the following parameters:

     Status Type/ID              Mandatory
     Routing Context            Optional
     INFO String                Optional

The format for SG or IPSP that initiated the NTFY message request, the M3UA will
send an M-SCTP ESTABLISH confirm to Layer Management when the
association set-up is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 13             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Status Type            |    Status Identification      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 6              |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                       Routing Context*                        /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 4              |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \                                                               \
   /                          INFO String*                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Status Type: 16-bits (unsigned integer)

   The Status Type parameter identifies complete.  At the type peer M3UA layer, an M-SCTP
ESTABLISH indication is sent to Layer Management upon successful
completion of an incoming SCTP association set-up.

An M-SCTP RELEASE request from Layer Management initates the Notify message.
   Following are tear-down
of an SCTP association.  M3UA accomplishes a graceful shutdown of the valid Status Type values:

         1     Application Server State Change (AS-StateChange)
         2     Other

Status Information: 16-bits (unsigned integer)

   The Status Information parameter contains more detailed information
   for
SCTP association by sending a SHUTDOWN primitive to the notification, based on SCTP layer.

When the value graceful shutdown of the Status Type.

   If SCTP association has been
accomplished, the Status Type is AS_State_Change SCTP layer returns a SHUTDOWN COMPLETE notification

to the following Status
   Information values are used:

         1    reserved
         2    Application Server Inactive (AS-Inactive)
         3    Application Server Active (AS-Active)
         4    Application Server Pending (AS-Pending)
   These notifications are sent from local M3UA Layer.  At the M3UA Layer that initiated the request,
the M3UA will send an SG M-SCTP RELEASE confirm to Layer Management when
the association teardown is complete.   At the peer M3UA Layer, an ASP M-
SCTP RELEASE indication is sent to Layer Management upon successful
tear-down of an SCTP association.

An M-SCTP STATUS request supports a change in Layer Management query of the local
status of a particular Application Server. SCTP association.  The value reflects M3UA simply maps the
   new state of M-
SCTP STATUS request to a STATUS primitive to the Application Server.

   If SCTP.  When the SCTP
responds, the M3UA maps the association status information to an M-SCTP
STATUS confirm.  No peer protocol is invoked.

Similar LM-to-M3UA-to-SCTP and/or SCTP-to-M3UA-LM mappings can be
described for the various other SCTP Upper layer primitives in RFC2960
such as Initialize, Set Primary, Change Heartbeat, Request Heartbeat,
Get SRTT Report, Set Failure Threshold, Set Protocol parameters,
Destroy SCTP Instance, Send Failure, and Network Status Change.
Alternatively, these SCTP Upper Layer primitives (and Status as well)
can be considered for modeling purposes as a Layer Management
interaction directly with the Status Type is Other, then SCTP Layer.

M-NOTIFY indication and M-ERROR indication primitives indicate to Layer
Management the following Status Information
   values are defined:

         1    Insufficient ASP resources active notification or error information contained in AS
         2    Alternate ASP Active a
received M3UA Notify or Error message respectively.  These notifications are not indications
can also be generated based on local M3UA events.

An M-ASP STATUS request supports a Layer Management query of the SG reporting the state change status
of an ASP a particular local or AS.  In the Insufficent ASP Resources case, remote ASP.  The M3UA responds with the SG is
indicating to an "Inactive" ASP(s) status
in the AS that another ASP an M-ASP STATUS confirm.  No M3UA peer protocol is
required in order to handle the load invoked.

An M-AS STATUS request supports a Layer Management query of the AS (Load-sharing mode).
For the Alternate ASP Active case, status
of a particular AS.  The M3UA responds with an ASP M-AS STATUS confirm.  No
M3UA peer protocol is informed when invoked.

M-ASP-UP request, M-ASP-DOWN request, M-ASP-ACTIVE request and M-ASP-
INACTIVE request primitives allow Layer Management at an alternate ASP transitions to the ASP-Active
initiate state in Over-ride mode.

The format and description of the optional Routing Context and Info
String parameters changes.  Upon successful completion, a corresponding
confirm is the same as for the ASPAC message (See Section
3.4.6.)

4.0 Procedures

The M3UA layer needs to respond to various local primitives it receives
from the SCTP and M3UA-User layers and Layer Management as well as the
messages that it receives from the peer M3UA layers.  This section
describes provided by the M3UA procedures in response to these events.

4.1 Procedures Layer Management.  If an invocation
is unsuccessful, an Error indication is provided.

These requests result in outgoing M3UA ASP-UP, ASP-DOWN, ASP-ACTIVE and
ASP-INACTIVE messages to support the services of the remote M3UA layer

4.1.1 peer at an SG or IPSP.

4.2 Receipt of primitives M3UA Peer Management messages

Upon successful state changes resulting from the M3UA-User

On receiving an MTP-Transfer request primitive reception of M3UA ASP-UP,
ASP-DOWN, ASP-ACTIVE and ASP-INACTIVE messages from an upper layer, or
the nodal inter-working function at an SG, a peer M3UA, the

M3UA layer sends a MUST invoke corresponding DATA message (see Section 3) M-ASP UP, M-ASP DOWN, M-ASP ACTIVE
and M-ASP INACTIVE, M-AS ACTIVE, M-AS INACTIVE, and M-AS DOWN
indications to its M3UA peer.  The M3UA
peer receiving the Data message sends an MTP-Transfer local Layer Management.

M-NOTIFY indication
primitive to the upper layer.

The M3UA address translation and mapping function determines the
Application Server (AS) based on M-ERROR indication indicate to Layer Management
the notification or error information contained in the incoming
message.  From the list of ASPs within the AS table, an Active ASP is
selected and a DATA message is constructed and issued on the
corresponding SCTP Association.  If more than one ASP is active (i.e.,
traffic is to be load-shared across all the active ASPs), one of the
active ASPs from the list is selected.  The selection algorithm is
implementation dependent but could, for example, be round-robin or
based on, for example, the SLS received M3UA
Notify or ISUP CIC.  The appropriate selection
algorithm must be chosen carefully as it is dependent Error message.  These indications can also be generated based
on application
assumptions and understanding of local M3UA events.

4.3 Procedures to support the degree M3UA Management services

These procedures support the M3UA management of state coordination SCTP Associations
between SGs and ASPs.

4.3.1 AS and ASP State Maintenance

The M3UA layer on the active ASPs in SG maintains the AS.

In addition, state of each remote ASP, in
each Application Server that the message needs ASP is configured to be sent on the appropriate SCTP
stream, again taking care receive traffic,
as input to meet the M3UA message sequencing needs distribution function.  Similarly, where
IPSPs use M3UA in a point-to-point fashion, the M3UA layer in an IPSP
maintains the state of remote IPSPs. For the
signalling application.

4.1.2 Receipt purposes of primitives from the Layer Management

On receiving primitives from following
procedures, only the local Layer Management, SG/ASP case is described but the M3UA
layer will take SG side of the requested action and provide a response
procedures also apply to Layer
Management.

An M-SCTP ESTABLISH request from Layer Management will initiate the
establishment of an SCTP association.  An M-SCTP ESTABLISH confirm will
be sent to Layer Management when the initiated association set-up is
complete.  An M-SCTP ESTABLISH indication is sent IPSP sending traffic to Layer Management
upon successful completion of an incoming SCTP association set-up from AS consisting of
a peer M3UA node

An M-SCTP RELEASE request from Layer Management initates the tear-
down set of an SCTP association.  An M-SCTP RELEASE confirm is sent to
Layer Management when the association teardown is complete.   An M-SCTP
RELEASE indication remote IPSPs.

4.3.1.1 ASP States

The state of each remote ASP, in each AS that it is sent configured to Layer Management upon successful tear-
down of an SCTP association initiated by a peer
operate, is maintained in the M3UA

An M-SCTP STATUS request supports a Layer Management query of layer in the local
status SG. The state of a
particular SCTP association. ASP in a particular AS changes due to events. The M3UA responds with events
include:

   * Reception of messages from the
association status in an M-SCTP STATUS confirm.  No peer protocol is
invoked.

An M-ASP STATUS request supports a Layer Management query M3UA layer at the ASP;
   * Reception of some messages from the status peer M3UA layer at other ASPs
     in the AS (e.g., ASPAC Take-over);
   * Reception of a particular local indications from the SCTP layer; or remote ASP.
   * Local Management intervention.

The M3UA responds with the status ASP state transition diagram is shown in Figure 4.  The possible
states of an M-ASP STATUS confirm.  No ASP are:

ASP-DOWN: The remote M3UA peer protocol at the ASP is invoked.

An M-AS STATUS request supports a Layer Management query of unavailable and/or the status
of a particular AS.  The
related SCTP association is down.  Initially all ASPs will be in this
state.  An ASP in this state should not be sent any M3UA responds with an M-AS STATUS confirm.  No messages.

ASP-INACTIVE: The remote M3UA peer protocol is invoked.

M-ASP-UP request, M-ASP-DOWN request, M-ASP-ACTIVE request and M-ASP-
INACTIVE request primitives allow Layer Management at an the ASP to
initiate state changes.  Upon successful completion, a corresponding
confirm is provided by the M3UA to Layer Management.  If available (and the invocation
is unsuccessful, an Error indication
related SCTP association is provided.

These requests result in outgoing M3UA ASP-UP, ASP-DOWN, ASP-ACTIVE and
ASP-INACTIVE messages to up) but application traffic is stopped.  In
this state the ASP can be sent any non-Data M3UA messages.

ASP-ACTIVE: The remote M3UA peer at an SG the ASP is available and
application traffic is active (for a particular Routing Context or IPSP.

4.2 Receipt of M3UA Peer Management messages

Upon successful state changes resulting from reception set
of Routing Contexts).

ASP-STANDBY: The remote M3UA ASP-UP,
ASP-DOWN, ASP-ACTIVE and ASP-INACTIVE messages from a peer M3UA, the
M3UA layer invoke corresponding M-ASP UP, M-ASP DOWN, M-ASP ACTIVE and
M-ASP INACTIVE, M-AS ACTIVE, M-AS INACTIVE, and M-AS DOWN indications
as appropriate to at the Layer Management.

M-NOTIFY indication ASP is available and M-ERROR indication indicate ready to Layer Management
the notification or error information contained in
receive application traffic at any time (for a received M3UA
Notify particular Routing
Context or Error message.  These indications set of Routing Contexts).  In this state the ASP can also be generated based
on local M3UA events.

4.3 Procedures to support the M3UA Management services

These procedures support the sent
any non-Data M3UA management of messages.

                 Figure 4: ASP State Transition Diagram

                                   +--------------+
                                   |  ASP-ACTIVE  |
            +----------------------|      or      |
            |    Alternate +-------| ASP-STANDBY* |
            |       ASP    |       +--------------+
            |     Takeover |           ^     |
            |              |    ASP    |     | ASP
            |              |    Active |     | Inact
            |              |           |     v
            |              |       +--------------+
            |              |       |              |
            |              +------>| ASP-INACTIVE |
            |                      +--------------+
            |                          ^     |
  ASP Down/ |                     ASP  |     | ASP Down /
  SCTP Associations
between SGs and ASPs.

4.3.1 AS CDI  |                     Up   |     | SCTP CDI
            |                          |     v
            |                      +--------------+
            |                      |              |
            +--------------------->|   ASP-DOWN   |
                                   |              |
                                   +--------------+

*Note: ASP-ACTIVE and ASP State Maintenance

The M3UA layer on the SG maintains the state of each remote ASP, ASP-STANDBY differ only in
each Application Server that whether the ASP is configured to receive traffic,
as input to
currently receiving Data traffic within the M3UA message distribution function.  Similarly, where
IPSPs use M3UA in a point-to-point fashion, AS.

SCTP CDI: The local SCTP layer's Communication Down Indication to the M3UA layer in
Upper Layer Protocol (M3UA) on an IPSP
maintains the state of remote ASPs in IPSPs. For SG. The local SCTP will send this
indication when it detects the purposes loss of connectivity to the
following procedures, only the SG/ASP case ASP's peer
SCTP layer.  SCTP CDI is described but the SG side
of understood as either a SHUTDOWN COMPLETE
notification or COMMUNICATION LOST notification from the procedures also apply to an IPSP sending traffic to an SCTP.

4.3.1.2  AS
consisting of remote ASPs in IPSPs.

4.3.1.1  ASP States

The state of each remote ASP, in each the AS that it is configured to
operate, is maintained in the M3UA layer in on the SG or IPSP. SG.

The state of a particular ASP in a particular an AS changes due to events. The These events include:

   * Reception of messages from the peer M3UA layer at the ASP
   * Reception of some messages from the peer M3UA layer at other ASPs
     in the AS (e.g., ASPAC Take-over)
   * Reception of indications from the SCTP layer

The ASP state transition diagram is shown in Figure 4. transitions
   * Recovery timer triggers

The possible states of an ASP AS are:

ASP-DOWN:

AS-DOWN: The remote M3UA peer at the ASP is unavailable and/or the
related SCTP association Application Server is down.  Initially unavailable.  This state implies
that all related ASPs are in the ASP-DOWN state for this AS. Initially
the AS will be in this state.  An ASP in this state should not be sent any M3UA messages.

ASP-INACTIVE:

AS-INACTIVE: The remote M3UA peer at the ASP Application Server is available (and the
related SCTP association is up) but no application
traffic is stopped.  In
this state active (i.e., one or more related ASPs are in the ASP can be sent any non-Data M3UA messages.

ASP-ACTIVE: The remote M3UA peer at ASP-
Inactive state, but none in the ASP ASP-Active state).  The recovery timer
T(r) is not running or has expired.

AS-ACTIVE: The Application Server is available and application traffic
is active (for a particular Routing Context or set
of Routing Contexts).

ASP-STANDBY: The remote M3UA peer active.  This state implies that at the least one ASP is available in the ASP-
ACTIVE state.

AS-PENDING: An active ASP has transitioned to inactive and ready it was the
last remaining active ASP in the AS (and no STANDBY ASPs are available.
A recovery timer T(r) will be started and all incoming SCN messages
will be queued by the SG. If an ASP becomes active before T(r) expires,
the AS will move to
receive application traffic at any time (for a particular Routing
Context or set of Routing Contexts).  In this AS-ACTIVE state and all the ASP can queued messages will be
sent
any non-Data M3UA to the active ASP.

If T(r) expires before an ASP becomes active, the SG stops queuing
messages and discards all previously queued messages.

                 Figure 4: The AS will move
to AS-INACTIVE if at least one ASP is in ASP-INACTIVE state, otherwise
it will move to AS-DOWN state.

                 Figure 5: AS State Transition Diagram

      +----------+   one ASP trans to ACTIVE   +-------------+
      |          |---------------------------->|             |
      | AS-INACT |                             |  AS-ACTIVE  |
      |          |<---                         |             |
      +----------+    \                        +-------------+
         ^   | ASP-ACTIVE         \ Tr Expiry,                ^    |
            +----------------------|      or
         |   |    Alternate +-------| ASP-STNDBY*          \ at least one             |    |
         |   |           \ ASP in INACT            |       +-------------+    |     Takeover
         |           ^   |            \                        |    |
         |   |             \                       |    |
         |   |              \                      |    |
 one ASP |   | all ASP       \            one ASP  |    |    Active Last ACT ASP
 trans   |   | Inact trans to       \           trans to |    | trans to
INACT
 to INACT|   |     v DOWN            -------\   ACTIVE   |    |       +-------------+ or DOWN
         |   |                         \           |    |
         |              +------>|  ASP-INACT   |                          \          |                      +-------------+    |                          ^
         |
  ASP Down/   |                     ASP                           \         |    | ASP Down /
  SCTP CDI
         |                     Up   |                            \        | SCTP CDI    |
         |   v                             \       |    v
      +----------+                          \  +-------------+
      |          |                           --|             |
      |
            +--------------------->| AS-DOWN  |                             |  ASP-DOWN AS-PENDING  |
      |          |                             |  (queueing) |
      |          |<----------------------------|             |
      +----------+       Tr Expiry no ASP      +-------------+

*Note: ASP-ACTIVE and ASP-STNDBY differ only
                         in whether INACT state

    Tr = Recovery Timer

4.3.2 M3UA Management procedures for primitives

Before the establishment of an SCTP association the ASP state at both
the SG and ASP is
currently receiving Data traffic. assumed to be "Down".

Once the SCTP CDI: The association is established (See Section 4.1.2) and
assuming that the local SCTP layer's Communication Down Indication M3UA-User is ready, the local ASP M3UA
Application Server Process Maintenance (ASPM) function will initiate
the ASPM procedures, using the ASP-Up/-Down/-Active/-Inactive messages
to convey the
Upper Layer Protocol (M3UA) on ASP-state to the SG - see Section 4.3.3.

If the M3UA layer subsequently receives an SG. The local SCTP-Communication Down
indication from the underlying SCTP layer, it will send this inform the Layer
Management by invoking the M-SCTP STATUS indication when it detects primitive. The
state of the remote ASP will be moved to "Down".  At an ASP, the MTP3-
User at an ASP will be informed of the loss unavailability of connectivity to any affected
SS7 destinations through the ASP's peer
SCTP layer.  SCTP CDI is understood as either a SHUTDOWN COMPLETE
notification or COMMUNICATION LOST notification from use of MTP-PAUSE primitives.  In the SCTP.

4.3.1.2  AS States

The state case

of SS7 network isolation, the AS local MTP3-Users may be informed by
implementation-dependent means as there is maintained in currently no primitive
defined for conveying this information.

At an ASP, the Layer Management may try to re-establish the SCTP
association using M-SCTP ESTABLISH request primitive.

4.3.3 M3UA layer Management procedures for peer-to-peer messages

All M3UA MGMT and ASP Maintenance messages are sent on the SG.

The state of an AS changes due a sequenced
stream to events. These events include:

   * ensure ordering.  SCTP stream '0' is used.

4.3.3.1 ASP-Up

After an ASP state transitions
   * Recovery timer triggers

The possible states of has successfully established an AS are:

AS-DOWN: The Application Server is unavailable.  This state implies
that all related ASPs are in SCTP association to an SG,
the ASP-DOWN state SG waits for this AS. Initially the AS will be in this state.

AS-INACTIVE: The Application Server ASP to send an ASP-Up message, indicating that the
ASP M3UA peer is available but no application
traffic available.  The ASP is active (i.e., one or more related ASPs are in always the ASP-
Inactive state, but none in initiator of the ASP-Active state).

AS-ACTIVE: The Application Server is available and application traffic
ASP-Up exchange.  This action MAY be initiated at the ASP by an M-ASP
UP request primitive from Layer Management or may be initiated
automatically by an M3UA management function.

When an ASP-Up message is active.  This state implies that received at least one an SG and internally the remote
ASP is in the ASP-
ACTIVE state.

AS-PENDING: An active "Down" state and not considered locked-out for local
management reasons, the SG marks the remote ASP has transitioned to inactive as "Inactive" and
informs Layer Management with an M-ASP-Up indication primitive.  If the
SG knows, via current configuration data, which Application Servers the
ASP is configured to operate in, it was can update the
last remaining active ASP status to
"Inactive" in the each AS (and no STANDBY ASPs are available.
A recovery timer T(r) will be started and all incoming SCN messages
will be queued by that it is a member.  Alternatively, the SG may
move the SG. If an ASP becomes active before T(r) expires, into a pool of Inactive ASPs available for future
activation in Application Server(s) denoted in the AS will move subsequent ASP-
Active Routing Contexts.  The SG responds with an ASP-Up Ack message in
acknowledgement.  The SG sends an ASP-Up Ack message in response to AS-ACTIVE state and all a
received ASP-Up message even if the queued messages will be
sent to ASP is already marked as "Inactive"
at the active ASP. SG.

If T(r) expires before for any local reason (e.g., management lock-out) the SG cannot
respond with an ASP becomes active, ASP-Up Ack, the SG stops queuing
messages and discards all previously queued messages. The AS will move responds to AS-INACTIVE if at least one ASP an ASP-Up with an ASP-
Down Ack message with Reason "Management Blocking".

At the ASP, the ASP-Up Ack message received is not acknowledged. Layer
Management is in ASP-INACTIVE state, otherwise informed with an M-ASP UP confirm primitive .

When the ASP sends an ASP-Up message it will move to AS-DOWN state.

                 Figure 5: AS State Transition Diagram

      +----------+   one starts timer T(ack).  If the
ASP trans does not receive a response to ACTIVE   +-------------+
      |          |---------------------------->|             |
      | AS-INACT |                             |  AS-ACTIVE  |
      |          |<---                         |             |
      +----------+    \                        +-------------+
         ^   |         \ Tr Expiry,                ^    |
         |   |          \ at least one             |    |
         |   |           \ an ASP-Up within T(ack), the ASP MAY
restart T(ack) and resend ASP-Up messages until it receives an ASP-Up
Ack message.  T(ack) is provisionable, with a default of 2 seconds.
Alternatively, retransmission of ASP-Up messages may be put under
control of Layer Management.  In this method, expiry of T(ack) results
in INACT            |    |
         |   |            \                        |    |
         |   |             \                       |    |
         |   |              \                      |    |
 one ASP |   | all ASP       \            one ASP  |    | Last ACT ASP
 trans   |   | trans to       \           trans to |    | trans to
INACT
 to INACT|   | DOWN            -------\   ACTIVE   |    | or DOWN
         |   |                         \           |    |
         |   |                          \          |    |
         |   |                           \         |    |
         |   |                            \        |    |
         |   v                             \       |    v
      +----------+                          \  +-------------+
      |          |                           --|             |
      | AS-DOWN  |                             | AS-PENDING  |
      |          |                             |  (queueing) |
      |          |<----------------------------|             |
      +----------+       Tr Expiry no a M-ASP-Up confirmation carrying a negative indication.

The ASP      +-------------+
                         in INACT state

    Tr = Recovery Timer

4.3.2 M3UA Management procedures must wait for primitives

Before the establishment of an SCTP association ASP-Up Ack message before sending any other
M3UA messages (e.g., ASPAC, REG REQ).  If the SG receives any other
M3UA messages before an ASP state at both Up is received, the SG and ASP should discard them.

If an ASP-Up is assumed to be "Down".

As received and internally the remote ASP is responsible for initiating in the setup of an SCTP
association to
"Active" or "Standby" state, an SG, Error ("Unexpected Message) is returned
and the M3UA layer at an remote ASP receives state is not changed.

If an M-SCTP
ESTABLISH request primitive from ASP-Up is received and internally the Layer Management. remote ASP is already in
the M3UA layer "Inactive" state, and ASP-Up Ack is returned and no action is
taken.

4.3.3.2 ASP-Down

The ASP will try send an ASP-Down to establish an SCTP association with SG when the remote ASP wishes to be
removed from service in all Application Servers that it is a member and
no longer receive any M3UA peer traffic or management messages.  This action
MAY be initiated at the ASP by an SG.  Upon reception of an eventual SCTP-Communication Up confirm M-ASP DOWN request primitive from the SCTP, the M3UA layer will invoke the primitive M-
SCTP ESTABLISH confirm to the
Layer Management.

The Management or may be initiated automatically by an M3UA layers at
management function.

Whether the SG will receive an SCTP-CommunicationUp
indication primitive ASP is permanently removed from the SCTP when the association any AS is successfully
set up. a function of
configuration management.

The M3UA layer will then invoke SG marks the primitive M-SCTP ESTABLISH ASP as "Down", informs Layer Management with an M-ASP-
Down indication primitive, and returns an ASP-Down Ack message to the Layer Management.

Once
ASP if one of the SCTP association following events occur:

    - an ASP-Down message is established and assuming that received from the local
M3UA-User ASP,
    - another ASPM message is ready, received from the local ASP M3UA Application Server Process
Maintenance (ASPM) function will initiate and the ASPM procedures, using SG has
      locked out the ASP-Up/-Down/-Active/-Inactive messages ASP for management reasons.

The SG sends an ASP-Down Ack message in response to convey a received ASP-Down
message from the ASP-state to ASP even if the SG - see Section 4.3.3.

If ASP is already marked as "Down" at the M3UA layer subsequently receives an SCTP-Communication Down
indication from
SG.

At the underlying SCTP layer, it will inform ASP, the ASP-Down Ack message received is not acknowledged.
Layer Management by invoking the M-SCTP STATUS indication is informed with an M-ASP Down confirm primitive. The
state of

When the remote ASP will be moved to "Down".  At sends an ASP, ASP-Down it starts timer T(ack).  If the MTP3-
User at ASP does
not receive a response to an ASP-Down within T(ack), the ASP will be informed MAY
restart T(ack) and resend ASP-Down messages  until it receives an ASP-
Down Ack message.  T(ack) is provisionable, with a default of the unavailability 2
seconds.  Alternatively, retransmission of any affected
SS7 destinations through the use ASP-Down messages may be put
under control of MTP-PAUSE primitives. Layer Management.  In the case this method, expiry of SS7 network isolation, the local MTP3-Users may be informed by
implementation-dependent means as there T(ack)
results in a M-ASP-Down confirmation carrying a negative indication.

4.3.3.3 M3UA Version Control

If an ASP-Up message with an unsupported version is currently no primitive
defined for conveying this information.

At received, the
receiving end responds with an ASP, Error message, indicating the Layer Management may try to re-establish version
the SCTP
association using M-SCTP ESTABLISH request primitive.

4.3.3 M3UA Management procedures for peer-to-peer messages

All M3UA MGMT receiving node supports and ASP Maintenance messages notifies Layer Management.

This is useful when protocol version upgrades are sent on being performed in a sequenced
stream
network.  A node upgraded to ensure ordering.  SCTP stream '0' a newer version should support the older
versions used on other nodes it is used.

4.3.3.1 communicating with.  Because ASPs
initiate the ASP-Up

After an procedure it is assumed that the Error message
would normally come from the SG.

4.3.3.4 ASP-Active

Anytime after the ASP has successfully established an SCTP association to received an SG
or IPSP, ASP-Up Ack from the SG or IPSP waits for IPSP,
the ASP to send sends an ASP-Up message, ASP-Active (ASPAC) to the SG indicating that the ASP M3UA peer is available.  The ASP
is always the
initiator of the ASP-Up exchange. ready to start processing traffic.  This action MAY be initiated at
the ASP by an M-ASP UP Active request primitive from Layer Management or
may be initiated automatically by an M3UA management function.   In the
case where an ASP wishes to process the traffic for more than one
Application Server across a common SCTP association, the ASPAC contains
a list of one or more Routing Contexts to indicate for which
Application Servers the ASPAC applies. It is not necessary for the ASP
to include all Routing Contexts of interest in the initial ASPAC
message, thus becoming active in all Routing Contexts at the same time.
Multiple ASPAC messages MAY be used to activate within the Application
Servers independently.  In the case where an ASP-Active message does
not contain a Routing Context parameter, the receiver must know, via
configuration data, which Application Server(s) the ASP is a member.

When an ASP-Up ASP Active (ASPAC) message is received at an received, the SG or IPSP and internally responds
with an ASPAC Ack message(with the
remote ASP is not considered locked-out for local management reasons, same Type value contained in the SG marks
received APAC), acknowledging that the ASPAC was received and,
depending on the ASPAC Type value, moves the remote ASP as 'Inactive' and informs to the "Active" or
"Standby" state within the associated Application Server(s). Layer
Management is informed with an M-ASP-Up ASP-Active indication primitive. If the
SG knows via
configuration data which Application Servers that or IPSP receives any Data messages before an ASPAC is received, the ASP
SG or IPSP should discard them.  By sending an ASPAC Ack, the SG or
IPSP is configured now ready to operate in, it can update receive and send traffic for the related Routing
Contexts.  The ASP status to "Inactive" MUST not send Data messages before receiving an
ASPAC Ack.

Multiple ASPAC Ack messages MAY be used in each AS
pool that it is a member.  Alternatively, response to an ASPAC
containing multiple Routing Contexts, allowing the SG may move the ASP into
a pool of Inactive ASPs available or IPSP to
independently Ack for future activation in AS pool(s)
denoted in the subsequent ASP-Active different (sets of) Routing Contexts.  The SG responds
with or
IPSP sends an ASP-Up Ack Error ("Invalid Routing Context") message for each
invalid or un-configured Routing Context value in acknowledgement. a received ASPAC
message.

The SG sends MUST send an ASP-Up ASP-Active Ack message in response to a received ASP-Up
ASP-Active message even if from the ASP and the ASP is already marked as "Inactive" at the SG.

If for any local reason (e.g., management lock-out) the SG cannot
respond with an ASP-Up Ack, the SG responds to an ASP-Up with an ASP-
Down Ack message with Reason "Management Blocking".
"Active" at the SG.

At the ASP, the ASP-Up ASP-Active Ack message received is not acknowledged.
Layer Management is informed with an M-ASP UP Active confirm primitive . primitive.

When the Asp ASP sends an ASP-Up ASP-Active it starts timer T(ack).  If the ASP
does not receive a response to an ASP-Up ASP-Active within T(ack), the ASP MAY
restart T(ack) and resend ASP-Up ASP-Active messages until it receives an ASP-Up ASP-
Active Ack message.  T(ack) is provisionable, with a default of 2
seconds.  Alternatively, retransmission of ASP-Up ASP-Active messages may be
put under control of Layer Management.  In this method, expiry of
T(ack) results in a M-ASP-Up M-ASP-Active confirmation carrying a negative
indication.

There are four modes of Application Server traffic handling in the SG
M3UA - Over-ride, Over-ride (Standby), Loadshare and Load-share
(Standby).  The ASP must wait for Traffic Mode Type parameter in the ASP-Up Ack ASPAC message before sending any ASP
messages (e.g., ASPAC).
indicates the traffic handling mode used in a particular Application
Server. If the remote peer receives any other M3UA
messages before SG determines that the mode indicated in an ASP Up ASPAC is received,
unsupported or incompatible with the mode currently configured for the
AS, the remote peer should
discard them.

4.3.3.2 ASP-Down

The ASP will send an ASP-Down to an SG or IPSP when responds with an Error message indicating "Unsupported /
Invalid Traffic Handling Mode".  If the Traffic Handling mode of the ASP wishes to
be removed from service in all
Application Servers that it Server is a member
And no longer receive any M3UA traffic or management messages.  This
action not already known via configuration data, then
the Traffic handling mode indicated in the first ASPAC message causing
the transition of the Application Server state to "Active" MAY be initiated at used
to set the ASP by an M-ASP DOWN request primitive
from Layer Management or may be initiated automatically by an M3UA
management function.

Whether mode.

In the ASP is permanently removed from any AS is a function case of
configuration management.

The SG marks the ASP as "Down", informs Layer Management with an M-ASP-
Up indication primitive, and returns Over-ride mode AS, reception of an ASP-Down Ack ASPAC message to at
an SG causes the ASP
if one redirection of all traffic for the following events occur:

    - an ASP-Down message is received from AS to the ASP,
    - another ASPM message is received from ASP that
sent the ASPAC.  Any previously active ASP in the AS is now considered
Inactive and will no longer receive traffic from the SG has
      locked out within the ASP for management reasons. AS.
The SG or IPSP sends an ASP-Down Ack message a Notify (Alternate ASP-Active) to the previously
active ASP in response the AS, after stopping all traffic to that ASP.

In the case of Over-ride (Standby) mode the traffic is not started to a received ASP-Down
message from
the ASP even if until the previously active ASP is already marked as transitions to "Inactive or
"Down" at the
SG. state.  At this point the ASP, ASP that sent the ASP-Down Over-Ride (Standby)
ASPAC is moved to the Active state and the traffic is redirected.  A
second ASP-Active Ack message received with a new Traffic Mode Type ("Over-
ride", previously "Over-ride(Standby)") is not acknowledged.
Layer Management sent to the ASP. A Notify
(Alternate ASP-Active) message is informed with not sent in this case.

In the case of a Load-share mode AS, reception of an M-ASP Down confirm primitive.

When ASPAC message at
an SG or IPSP causes the direction of traffic to the ASP sending the
ASPAC, in addition to all the other ASPs that are currently active in
the AS.  The algorithm at the SG for load-sharing traffic within an AS

to all the active ASPs is implementation dependent.  The algorithm
could, for example be round-robin or based on information in the Data
message (e.g., such as the Asp sends SLS, SCCP SSN, ISUP CIC value).

An SG or IPSP, upon reception of an ASP-Down it starts timer T(ack).  If ASPAC for the first ASP does
not receive in a response
Loadshare AS, MAY choose not to an ASP-Down within T(ack), the direct traffic to a newly active ASP MAY
restart T(ack) and resend ASP-Down messages
until it receives an
ASP-Down Ack message.  T(ack) is provisionable, with a default of 2
seconds.  Alternatively, retransmission of ASP-Down messages may be put
under control of Layer Management. determines that there are sufficient resources to handle the
expected load (e.g., until there are sufficient ASPs "Active" in the
AS).

In this method, expiry the case of T(ack)
results in a M-ASP-Down confirmation carrying a negative indication.

4.3.3.3 M3UA Version Control

If an ASP-Up message with an unsupported version Load-share (Standby) mode, the traffic is received, not started to
the
receiving end responds with an Error message, indicating ASP until the version SG or IPSP determines that there are insufficient
resources available in the receiving node supports and notifies Layer Management. AS.  This is useful likely when protocol version upgrades are being performed in a
network.  A node upgraded one of the active
load-sharing ASPs transitions to a newer version should support the older
versions used on other nodes it "Inactive" or "Down" state.  At
this point the ASP that sent the Load-share (Standby) ASPAC is communicating with.  Because ASPs
initiate moved to
the ASP-Up procedure it Active state and traffic is assumed that started.  A second ASP-Active Ack
message with a new Traffic Mode Type ("Load-share" - previously
"Loadshare(Standby)") is sent to the Error ASP. A Notify ("Insufficient ASP
resources active in AS ") message
would normally come from is not sent in this case.

All ASPs within a load-sharing mode AS must be able to handle any
traffic within the SG.

4.3.3.4 ASP-Active

Anytime after AS, in order to accommodate any potential fail-over
or rebalancing of the offered load.

4.3.3.5 ASP has received Inactive

When an ASP-Up Ack ASP wishes to withdraw from the SG or IPSP, receiving traffic within an AS, the
ASP sends an ASP-Active (ASPAC) ASP Inactive (ASPIA) to the SG indicating that the ASP
is ready to start processing traffic. or IPSP.  This action MAY
be initiated at the ASP by an M-ASP Active INACTIVE request primitive from
Layer Management or may be initiated automatically by an M3UA
management function.   In the case where an ASP wishes to process is processing the
traffic for more than one Application Server across a common SCTP
association, the ASPAC ASPIA contains
a list of one or more Routing Contexts to
indicate for which Application Servers the ASPAC ASPIA applies.  In the case
where an ASP-Active ASP-Inactive message does not contain a Routing Context, Context
parameter, the receiver must know, via configuration data, which AS pools
Application Servers the ASP will be a member.

When an ASP Active (ASPAC) message is received, a member and move the SG or IPSP responds ASP to the
"Inactive" state in each AS.

In the case of an Over-ride mode AS, where another ASP has already
taken over the traffic within the AS with an ASPAC Over-ride ASPAC, the ASP
that sends the ASPIA is already considered by the SG to be "Inactive".
An ASPIA Ack message, acknowledging message is sent to the ASP, after ensuring that all
traffic is stopped to the ASPAC was
received and, depending on ASP.

In the ASPAC Type value received, case of a Load-share mode AS, the SG moves the ASP ASP to the
"Inactive" state and the AS traffic is re-allocated across the
remaining "active" ASPs per the load-sharing algorithm currently used
within the AS.  A NTFY(Insufficient ASP resources active in AS) may be
sent to all inactive ASPs, if required.  However, if a Loadshare

(Standby) ASP is available, it may be now immediately included in the
loadshare group and a Notify message is not sent.  An ASPIA Ack message
is sent to the "Active" or "Standby" state within the associated Application
Server(s). ASP after all traffic is halted and Layer Management is
informed with an ASP-Active ASP-INACTIVE indication primitive.  The ASP MUST not send Data

Multiple ASPIA Ack messages before receiving MAY be used in response to an
ASPAC Ack.  If ASPIA
containing multiple Routing Contexts, allowing the SG or IPSP receives any Data messages before an
ASPAC is received, the to
independently Ack for different (sets of) Routing Contexts.  The SG or
IPSP should discard them. sends an Error ("Invalid Routing Context") message for each
invalid or un-configured Routing Context value in a received ASPIA
message.

The SG sends MUST send an ASP-Active ASP-Inactive Ack message in response to a received ASP-
Active
ASP-Inactive message from the ASP even if and the ASP is already marked as
"Active"
"Inactive" at the SG.

At the ASP, the ASP-Active ASP-INACTIVE Ack message received is not acknowledged.
Layer Management is informed with an M-ASP Active INACTIVE confirm primitive.
When the ASP sends an ASP-Active ASP-Inactive it starts timer T(ack).  If the ASP
does not receive a response to an ASP-Active ASP-Inactive within T(ack), the ASP
MAY restart T(ack) and resend ASP-Active ASP-Inactive messages  until it receives
an ASP-Active ASP-Inactive Ack message.  T(ack) is provisionable, with a default
of 2 seconds.  Alternatively, retransmission of ASP-Active ASP-Inactive messages
may be put under control of Layer Management.  In this method, expiry
of T(ack) results in a M-ASP-Active M-ASP-Inactive confirmation carrying a negative
indication.

There

If no other ASPs are two modes of Application Server traffic handling in the SG
M3UA - Over-ride and Load-share.  The Type parameter "Active" or "Standby" in the ASPAC
message indicates the traffic handling mode used in a particular Application Server. If the SG determines that the mode indicated in an
ASPAC is incompatible with the mode currently used in the AS, the SG
responds with an Error message indicating "Invalid Traffic Handling
Mode".

In the case of an Over-ride mode AS, reception of an ASPAC message at
an SG causes the redirection of all traffic for the AS to the ASP that
sent the ASPAC.  Any previously active ASP in the AS is now considered
Inactive and will no longer receive traffic from the SG within Server,
the AS.
The SG or IPSP SG sends a Notify (Alternate ASP-Active) NTFY(AS-Pending) to all inactive ASPs of the previously
active ASP in the AS, after stopping AS and
either discards all traffic to that ASP.  In incoming messages for the
case of Over-ride (Standby) mode AS or starts buffering
the actions are incoming messages for T(r)seconds, after which messages will be
discarded.  T(r) is configurable by the same with network operator.  If the
exception that SG
receives an ASPAC from an ASP in the AS before expiry of T(r), the
buffered traffic is not started directed to the ASP until the
previously active ASP transitions to "Inactive or "Down" state.  At
this point and the ASP that sent timer is cancelled.  If
T(r) expires, the Over-Ride (Standby) ASPAC AS is moved to the Active state and the traffic is redirected. "Inactive" state.

4.3.3.6 Notify

A Notify message is
not sent in this case.

In the case of reflecting a Load-share mode AS, reception of an ASPAC message at
an SG or IPSP causes the direction of traffic to the ASP sending the
ASPAC, in addition to all the other ASPs that are currently active change in the AS.  The algorithm at the SG for load-sharing traffic within an AS state is sent to all the active
ASPs is implementation dependent.  The algorithm
could, for example be round-robin or based on information in the Data
message (e.g., such as the SLS, SCCP SSN, ISUP CIC value).

In the case of Load-share (Standby) mode, the actions are AS, except those in the same "Down" state, with appropriate
Status Identification.  At the exception that the traffic ASP, Layer Management is not started to the ASP until the SG
or IPSP determines that there are insufficient resources available in informed with
an M-NOTIFY indication primitive.

In the AS.  This case where a Notify (AS-Pending) message is likely due to one of the active load-sharing sent by an SG that
now has no ASPs
transitions active to service the "Inactive" traffic, or "Down" state.  At this point the a NTFY(Insufficient
ASP
that resources active in AS) is sent in the Load-share (Standby) ASPAC s moved to Loadshare mode, the Active state
and traffic is started.  A Notify message is
does not sent in this case.

All ASPs within a load-sharing mode AS must be able explicitly compel the ASP(s) receiving the message to handle any become
active. The ASPs remain in control of what (and when) traffic within action is
taken.

4.3.3.7 Heartbeat

The optional Heartbeat procedures may be used when operating over
transport layers that do not have their own heartbeat mechanism for
detecting loss of the AS, transport association (i.e., other than the
SCTP).

After receiving an ASP-Up Ack message from an M3UA peer in order response to accommodate any potential fail-over
or rebalancing of the offered load.

A node that receives
an ASPAC with ASP-Up message, an incorrect Type for ASP may optionally send Beat messages
periodically, subject to a particular
Routing Context will provisionable timer T(beat).  Upon receiving
a BEAT message, the M3UA peer MUST respond with an Error Message (Cause: Invalid
Traffic Handling Mode).  A node that receives an unknown Routing
Context value responds with an Error a BEAT ACK message.  If
no BEAT ACK message (Cause: Invalid Routing
Context).

4.3.3.5 (or any other M3UA message), is received by the ASP Inactive

When an
within the timer 2*T(beat), the ASP wishes to withdraw will consider the remote M3UA peer
as "Down".

At the ASP, if no BEAT ACK message (or any other M3UA message) is
received from receiving traffic the M3UA peer within an AS, 2*T(beat), the
ASP sends an ASP Inactive (ASPIA) remote M3UA peer is
considered unavailable.  Transmission of BEAT messages is stopped and
ASP-Up procedures are used to re-establish communication with the SG or IPSP.  This action MAY
be initiated at the ASP by an M-ASP INACTIVE request primitive from
Layer Management or
M3UA peer.

The BEAT message may be initiated automatically by optionally contain an M3UA
management function.   In opaque Heartbeat Data
parameter that MUST be echoed back unchanged in the case where an related Beat Ack
message.  The ASP is processing the
traffic for more than one Application Server across a common SCTP
association, the ASPIA contains one or more Routing Contexts to
indicate for which Application Servers upon examining the ASPIA applies.  In contents of the case
where an ASP-Inactive returned BEAT Ack
message does not contain a Routing Context, the
receiver must know via configuration data which AS pools MAY choose to consider the remote ASP as unavailable. The
contents/format of the Heartbeat Data parameter is a
member implementation-
dependent and move the ASP only of local interest to the "Inactive" state in each AS.

There original sender.  The
contents may be used, for example, to support a Heartbeat sequence
algorithm (to detect missing Heartbeats), and/or a timestamp mechanism
(to evaluate delays).

Note: Heartbeat related events are two modes of Application Server traffic handling not shown in the Figure 4 "ASP state
transition diagram".

4.3.4 Routing Key Management procedures

4.3.4.1 Registration

An ASP MAY dynamically register with an SG or
IPSP M3UA when withdrawing as an ASP from service - Over-ride and Load-
share.  The Type within an
Application Server using the REG REQ message. A Routing Key parameter
in the ASPIA message indicates REG REQ specifies the mode used
in a particular Application Server.  If parameters associated with the Routing
Key.

The SG or IPSP determines that examines the mode indicates in an ASPIA is inconsistent contents of the received Routing Key parameter and
compares it with the traffic
handling mode currently used in the AS, a this is reported to local
management indicating("Invalid Traffic Handling Mode").  The ASPIA is
still processed.

In provisioned Routing Keys.  If the case of
received Routing Key matches an Over-ride mode AS, where another existing SG Routing Key entry, and the
ASP has already
taken over is not currently included in the traffic within list of ASPs for the AS with an Over-ride ASPAC, related
Application Server, the ASP
that sends the ASPIA is already considered by MAY authorize the SG ASP to be "Inactive".
An ASPIA Ack message is sent added to the ASP, after ensuring that all
traffic is stopped to
AS.  Or, if the ASP.

In Routing Key does not currently exist and the case received
Routing Key data is valid and unique, an SG supporting dynamic

configuration MAY authorize the creation of a Load-share mode AS, the SG moves new Routing Key and
related Application Server and add the ASP to the
"Inactive" state and the AS traffic is re-allocated across new AS.  In either
case, the
remaining "active" ASPs per SG returns a Registration Response message to the load-sharing algorithm currently used

within ASP,
containing the AS.  A NTFY(Insufficient ASPs) may be sent to all inactive
ASPs, if required.  However, if a Loadshare (Standby) ASP is available,
it may be now immediately included same Local-RK-Identifier as provided in the loadshare group initial
request, and a Notify
message Registration Result "Successfully Registered".  A unique
Routing Context value assigned to the SG Routing Key is not sent.  An ASPIA Ack message included. The
method of Routing Context value assignment at the SG/SGP is sent
implementation dependent but must be guaranteed to the ASP after be unique across all
traffic is halted and Layer Management is informed with
SGPs in an ASP-INACTIVE
indication primitive.

At SG.

If the ASP, SG determines that the ASP-INACTIVE Ack message received Routing Key data is not acknowledged.
Layer Management is informed with an M-ASP INACTIVE confirm primitive.
When invalid, or
contains invalid parameter values, the ASP sends an ASP-Inactive it starts timer T(ack). SG returns a Registration
Response message to the ASP, containing a Registration Result "Error -
Invalid Routing Key", "Error - Invalid DPC, "Error - Invalid Network
Appearance" as appropriate.

If the ASP
does not receive SG determines that the Routing Key parameter overlaps with an
existing Routing Key entry, the SG returns a response Registration Response
message to an ASP-Inactive within T(ack), the ASP
MAY restart T(ack) and resend ASP-Inactive messages  until it receives
an ASP-Inactive Ack message.  T(ack) is provisionable, ASP, with a default
of 2 seconds.  Alternatively, retransmission of ASP-Inactive messages
may be put under control of Layer Management.  In this method, expiry Registration Status of T(ack) results in a M-ASP-Inactive confirmation carrying a negative
indication. "Error - Overlapping
(Non-Unique) Routing Key".  An incoming signalling message received at
an SG cannot match against more than one Routing Key.

If no other ASPs are "Active" or "Standby" in the Application Server, SG does not authorize the registration request, the SG sends returns a NTFY(AS-Pending)
REG RSP message to all inactive ASPs of the AS and
either discards all incoming messages for the AS or starts buffering the incoming messages for T(r)seconds, after which messages will be
discarded.  T(r) is configurable by ASP containing the network operator. Registration Result "Error 
Permission Denied".

If the SG
receives an ASPAC from an ASP in SG determines that a received Routing Key does not currently
exist and the AS before expiry of T(r), SG does not support dynamic configuration, the
buffered traffic is directed SG returns
a Registration Response message to the ASP ASP, containing a Registration
Result "Error - Routing Key not Provisioned".

If an SG determines that a received Routing Key does not currently
exist and the timer is cancelled.  If
T(r) expires, SG supports dynamic configuration but does not have the AS is moved
capacity to add new Routing Key and Application Server entries, the "Down" state.

4.3.3.6 Notify

A Notify message reflecting SG
returns a change in the AS state is sent Registration Response message to all
ASPs in the AS, except those in the "Down" state, with appropriate
Status Identification.  At the ASP, Layer Management is informed with
an M-NOTIFY indication primitive.

In the case where containing a Notify (AS-Pending) message is sent
Registration Result "Error - Insufficient Resources".

An ASP MAY register multiple Routing Keys at once by an including a number
of Routing Key parameters in a single REG REQ message.  The SG that
now has no ASPs active MAY
respond to service each registration request in a single REG RSP message,
indicating the traffic, success or a NTFY(Insufficient
ASPs) is sent failure result for each Routing Key in a
separate Registration Result parameter.  Alternatively the Loadshare mode, SG MAY
respond with multiple REG RSP messages, each with one or more
Registration Result parameters.  The ASP uses the Notify does not explicitly
force Local-RK-Identifier
parameter to correlate the ASP(s) receiving requests with the message to become active. The ASPs
remain in control of what (and when) action is taken.

4.3.3.7 Heartbeat

The optional Heartbeat procedures may be used when operating over
transport layers that do not have their own heartbeat mechanism for
detecting loss responses.

Upon successful registration of an ASP in an AS, the transport association (i.e., other than SG can now send
related SSNM messaging, if this did not previously start upon the
SCTP).

After receiving an ASP-Up Ack message from an M3UA peer in response ASP
transitioning to "Inactive".

4.3.4.2 Deregistration

An ASP MAY dynamically deregister with an ASP-Up message, SG as an ASP may optionally send Beat messages

periodically, subject to a provisionable timer T(beat).  Upon receiving
a BEAT message, within an
Application Server using the M3UA peer MUST respond with a BEAT ACK DEREG REQ message.  If
no BEAT ACK message (or any other M3UA message), is received by A Routing Context
parameter in the ASP
within DEREG REQ specifies which Routing Key to de-register.

The SG examines the timer 2*T(beat), contents of the received Routing Context parameter
and validates that the ASP will consider is currently registered in the remote M3UA peer
as "Down".

At Application
Server(s) related to the ASP, if no BEAT ACK message (or any other M3UA message) included Routing Context(s).  If validated,
the ASP is
received from de-registered as an ASP in the M3UA peer within 2*T(beat), related Application Server.

The deregistration procedure does not necessarily imply the remote M3UA peer is
considered unavailable.  Transmission deletion of BEAT messages is stopped
Routing Key and
ASP-Up procedures are used Application Server configuration data at the SG. Other
ASPs may continue to re-establish communication be associated with the SG
M3UA peer.

The BEAT message may optionally contain an opaque Heartbeat Data
parameter that MUST Application Server, in
which case the Routing Key data CANNOT be echoed back unchanged deleted.  If a Deregistration
results in no more ASPs in an Application Server, an SG MAY delete the related Beat Ack
message.
Routing Key data.

The ASP upon examining the contents of SG acknowledges the returned BEAT Ack
message MAY choose de-registration request by returning a DEREG
RSP to consider the remote ASP as unavailable. requesting ASP.  The
contents/format result of the Heartbeat Data parameter is implementation-
dependent and only of local interest to de-registration is found
in the original sender. Deregistration Result parameter, indicating success or failure
with cause.

An ASP MAY deregister multiple Routing Contexts at once by including a
number of Routing Contexts in a single DEREG REQ message.  The
contents may be used, for example, SG MUST
respond to support a Heartbeat sequence
algorithm (to detect missing Heartbeats), and/or each deregistration request in a timestamp mechanism
(to evaluate delays).

Note: Heartbeat related events are not shown single DEREG RSP message,
indicating the success or failure result for each Routing Context in Figure 4 "ASP state
transition diagram". a
separate Deregistration Result parameter.

4.4 Procedures to support the M3UA services

4.4.1 At an SG

On receiving an MTP-PAUSE, MTP-RESUME, or MTP-STATUS indication
primitive from the nodal inter-working function at an SG, the SG M3UA
layer will send a corresponding SSNM DUNA, DAVA, SCON, or DUPU message
(see Section 2) to the M3UA peers at concerned ASPs.  The M3UA layer
must fill in various fields of the SSNM messages consistently with the
information received in the primitives.

The SG M3UA determines the set of concerned ASPs to be informed based
on the SS7 network partition for which the primitive indication is
relevant. In this way, all ASPs configured to send/receive traffic
within a particular network appearance are informed.  If the SG
operates within a single SS7 network appearance, then all ASPs are
informed.

Optionally, the SG M3UA may filter further based on the Affected Point
Code in the MTP-PAUSE, MTP-Resume, or MTP-Status indication primitives.
In this way ASPs can be informed only of affected destinations to which
they actually communicate.  The SG M3UA may also suppress DUPU messages
to ASPs that do not implement an MTP3-User protocol peer for the
affected MTP3-User.

DUNA, DAVA, SCON messages must be sent on a sequenced stream as these
primitives should arrive in order.  Stream 0 is used.  Sequencing is
not required for the DUPU or DAUD message, which may optionally be sent
un-sequenced.  The same applies for the SCON message if the
international congestion method (see Q.704) is used.

4.4.2 At an ASP

4.4.2.1 Single SG configurations

At an ASP, upon receiving an SSNM message from the remote M3UA Peer,
the M3UA layer invokes the appropriate primitive indications to the
resident M3UA-Users.  Local management is informed.

In the case where a local event has caused the unavailability or
congestion status of SS7 destinations, the M3UA at the ASP should pass
up appropriate indications n the primitives to the M3UA User, as though
equivalent SSNM messages were received.  For example, the loss of an
SCTP association to an SG may cause the unavailability of a set of SS7
destinations.  MTP-Pause indications to the M3UA User is appropriate.
To accomplish this, the M3UA layer at an ASP maintains the status of
routes via the SG, much like an MTP3 layer maintains route-set status.

4.4.2.2 Multiple SG configurations

At an ASP, upon receiving an SSNM message from the remote M3UA Peer,
the M3UA layer updates the status of the affected route(s) via the
originating SG and determines, whether or not the overall availability
or congestion status of the effected destination(s) has changed. In
this case the M3UA layer invokes the appropriate primitive indications
to the resident M3UA-Users.  Local management is informed.

4.4.3 ASP Auditing

An ASP may optionally initiate an audit procedure in order to enquire
of an SG the availability and, if the congestion method with multiple
congestion levels and message priorities is used, congestion status of
an SS7 destination or set of destinations.  A Destination Audit (DAUD)
message is sent from the ASP to the SG requesting the current
availability and congestion status of one or more SS7 Destination Point
Codes.

The DAUD may be sent un-sequenced. The DAUD may be sent by the ASP in
the following cases:

   - Periodic.  A Timer originally set upon reception of DUNA or SCON
     message has expired without a subsequent DAVA, DUNA or SCON
     updating the availability/congestion status of the affected

     Destination Point Codes.  The Timer is reset upon issuing a DAUD.
     In this case the DAUD is sent to the SG that originally sent the
     SSNM message.

   - the ASP is newly "Inactive" or "Active" or has been isolated from
     an SG for an extended period.  The ASP can request the
     availability/congestion status of one or more SS7 destinations to
     which it expects to communicate.

In the first case, the DAUD procedure must not be invoked for the case
of  received SCON containing a congestion level value of "no
congestion" or undefined" (i.e., congestion Level = "0").  This is
because the value indicates either congestion abatement or that the ITU
MTP3 international congestion method is being used.  In the
international congestion method, the MTP3 at the SG MTP3 does not
maintain the congestion status of any destinations and therefore the SG
cannot provide any congestion information in response to the DAUD.  For
the same reason, in the second case a DAUD cannot reveal any congested
destination(s).

The SG MUST respond to a DAUD with the MTP3 status of the routeset
associated with each Destination Point Code(s) in the DAUD.  The status
of each SS7 destination requested is indicated in a DUNA (if
unavailable), DAVA (if available/uncongested) or an SCON (if
available/congested).  Optionally, any DUNA or DAVA message in response
to a DAUD may contain a list of up to sixteen Affected Point Codes.
Note that from the point of view of an ASP sending an DAUD, the
subsequent reception of an SCON implies that the Affected Destination
is available.  The reception of a DAVA implies that the routeset to the
Affected Destination is not congested.  Obviously with the reception of
an DUNA, the routeset to the Affected Destination can not also be
congested.

5.0 Examples of M3UA Procedures

5.1 Establishment of Association and Traffic between SGs and ASPs

5.1.1 ASPs

5.1.1a Single ASP in an Application Server ("1+0" sparing), No
Registration

This scenario shows the example M3UA message flows for the
establishment of traffic between an SG and an ASP, where only one ASP
is configured within an AS (no backup).  It is assumed that the SCTP
association is already set-up. The sending of DUNA/SCON messages by the
SG is not shown but would be similar to 5.1.2.

             SG                              ASP1
              |                                |
              |<-------------ASP Up------------|
              |-----------ASP-Up Ack---------->|
              |                                |
              |<------- ASP Active(RCn)--------|  RC: Routing Context
              |-----ASP Active Ack (RCn)------>|      (optional)
              |                                |

Note: If ASPAC contains an optional Routing Context parameter, The
ASPAC only applies for the specified RC value. For an unknown RC value,
the SG responds with an Error message.

5.1.1b Single ASP in Application Server ("1+0" sparing), With Dynamic
Registration

This scenario is the same as for 5.1.1a but with the optional exchange
of registration information.  In this case the Registration is accepted
by the SG.

             SG                              ASP1
              |                                |
              |<------------ASP Up-------------|
              |----------ASP-Up Ack----------->|
              |                                |
              |<----REGISTER REQ(LRCn,RKn)-----|  LRC: Local Routing
              |                                |       Context
              |----REGISTER RESP(LRCn,RCn)---->|   RK: Routing Key
              |                                |   RC: Routing Context
              |                                |
              |<------- ASP Active(RCn)--------|
              |-----ASP Active Ack (RCn)------>|
              |                                |

Note: In the case of an unsuccessful registration attempt (e.g.,
Invalid RKn), the Register Response will contain an unsuccessful
indication and the ASP will not subsequently send an ASPAC.

5.1.1c Single ASP in an multiple Application Server ("1+0" sparing)

This scenario shows the example M3UA message flows for Servers (each with "1+0"
sparing), With Dynamic Registration (Case 1  Multiple Registration
Requests)

             SG                              ASP1
              |                                |
              |<------------ASP Up-------------|
              |----------ASP-Up Ack----------->|
              |                                |
              |<----REGISTER REQ(LRC1,RK1)-----|  LRC: Local Routing
              |                                |       Context
              |----REGISTER RESP(LRC1,RC1)---->|   RK: Routing Key
              |                                |   RC: Routing Context
              |                                |
              |<------- ASP Active(RC1)--------|
              |-----ASP Active Ack (RC1)------>|
              |                                |
              :                                :
              :                                :
              |                                |
              |<----REGISTER REQ(LRCn,RKn)-----|
              |                                |
              |----REGISTER RESP(LRCn,RCn)---->|
              |                                |
              |                                |
              |<------- ASP Active(RCn)--------|
              |-----ASP Active Ack (RCn)------>|
              |                                |

Note: In the
establishment case of traffic between an SG and unsuccessful registration attempt (e.g.,
Invalid RKn), the Register Response will contain an ASP, where only one unsuccessful
indication and the ASP
is configured within will not subsequently send an AS (no backup). ASPAC. Each LRC/RK
pair registration is considered independently.

It is assumed that not necessary to follow a Registration Request/Response with an
ASP Active before sending the SCTP
association is already set-up. next Registration Request. The sending of DUNA/SCON messages by ASP Active
can happen any time after the
SG is not shown but would be similar to 5.1.2. related successful Registration.

5.1.1.d Single ASP in multiple Application Servers (each with "1+0"
sparing), With Dynamic Registration (Case 2  Single Registration
Request)

             SG                              ASP1
              |
              |<---------ASP Up----------|
              |-------ASP-Up Ack-------->|                                |
              |<------------ASP Up-------------|
              |----------ASP-Up Ack----------->|
              |
              |<-------ASP Active--------|                                |
              |<---REGISTER REQ({LRC1,RK1},----|
              |                   ...,         |
              |                 {LRCn,RKn}),----|
              |                                |
              |---REGISTER RESP({LRC1,RC1},--->|
              |                  ...,          |
              |                 (LRCn,RCn})    |
              |                                |
              |<------- ASP Active(RC1)--------|
              |-----ASP Active Ack------>| Ack (RC1)------>|
              |                                |
              :                                :
              :                                :
              |                                |
              |<------- ASP Active(RCn)--------|
              |-----ASP Active Ack (RCn)------>|
              |                                |

Note: In the case of an unsuccessful registration attempt (e.g.,
Invalid RKn), the Register Response will contain an unsuccessful
indication and the ASP will not subsequently send an ASPAC. Each LRC/RK
pair registration is considered independently.

The ASP Active can happen any time after the related successful
Registration, and may have more than one RC.

5.1.2 Two ASPs in Application Server ("1+1" sparing)

This scenario shows the example M3UA message flows for the
establishment of traffic between an SG and two ASPs in the same
Application Server, where ASP1 is configured to be "active" and ASP2 a
"standby" in the event of communication failure or the withdrawal from
service of ASP1.  ASP2 may act as a hot, warm, or cold standby
depending on the extent to which ASP1 and ASP2 share call/transaction
state or can communicate call state under failure/withdrawal events.
The example message flow is the same whether the ASP-Active messages
are Over-ride or Load-share mode although typically this example would
use an Over-ride mode. In the case of MTP Restart, the SG starts
sending any relevant DUNA and SCON messages to the ASPs as soon as they
enter the ASP-INACTIVE state. The ASP-Active Ack message is only sent
after all relevant DUNA/SCON messages have been transmitted to the
concerned ASP.

       SG                        ASP1                        ASP2
        |                         |                          |
        |<--------ASP Up----------|                          |
        |-------ASP-Up Ack------->|                          |
        |                         |                          |
        |<-----------------------------ASP Up----------------|
        |-----------------------------ASP-Up Ack------------>|
        |                         |                          |
        |                         |                          |
        |<-------ASP Active-------|                          |
        |------ASP-Active Ack---->|                          |
        |                         |                          |

5.1.3 Two ASPs in an Application Server ("1+1" sparing, load-sharing
case)

This scenario shows a similar case to Section 4.1.2 but where the two
ASPs are brought to "active" and load-share the traffic load.  In this
case, one ASP is sufficient to handle the total traffic load. The
sending of DUNA/SCON messages by the SG is not shown but would be
similar to 5.1.2.

       SG                       ASP1                       ASP2
        |                         |                          |
        |<---------ASP Up---------|                          |
        |--------ASP-Up Ack------>|                          |
        |                         |                          |
        |<------------------------------ASP Up---------------|
        |-----------------------------ASP Up Ack------------>|
        |                         |                          |
        |                         |                          |
        |<--ASP Active (Ldshr)----|                          |
        |-----ASP-Active Ack----->|                          |
        |                         |                          |
        |<----------------------------ASP Active (Ldshr)-----|
        |-------------------------------ASP-Active Ack------>|
        |                         |                          |

5.1.4 Three ASPs in an Application Server ("n+k" sparing, load-sharing
case)

This scenario shows the example M3UA message flows for the
establishment of traffic between an SG and three ASPs in the same
Application Server, where two of the ASPs are brought to "active" and
share the load. In this case, a minimum of two ASPs are required to
handle the total traffic load (2+1 sparing). The sending of DUNA/SCON
messages by the SG is not shown but would be similar to 5.1.2.

   SG                  ASP1                 ASP2                 ASP3
    |                    |                   |                   |
    |<------ASP Up-------|                   |                   |
    |-----ASP-Up Ack---->|                   |                   |
    |                    |                   |                   |
    |<--------------------------ASP Up-------|                   |
    |-------------------------ASP-Up Ack)--->|                   |
    |                    |                   |                   |
    |<---------------------------------------------ASP Up--------|
    |---------------------------------------------ASP-Up Ack---->|
    |                    |                   |                   |
    |                    |                   |                   |
    |<--ASP Act (Ldshr)--|                   |                   |
    |----ASP-Act Ack---->|                   |                   |
    |                    |                   |                   |
    |<--------------------ASP Act. (Ldshr)---|                   |
    |-----------------------ASP-Act Ack----->|                   |
    |                    |                   |                   |

5.2 ASP Traffic Fail-over Examples

5.2.1 (1+1 Sparing, withdrawal of ASP, Back-up Over-ride)

Following on from the example in Section 4.1.2, 5.1.2, and ASP ASP1 withdraws from
service:

       SG                       ASP1                       ASP2
        |                         |                          |
        |<-----ASP Inactive-------|                          |
        |----ASP Inactive Ack---->|                          |
        |------------------------NTFY(AS-Inact.)(Optional)-->|
        |------------------------NTFY(AS-Pending)----------->|
        |                         |                          |
        |<------------------------------ ASP Active----------|
        |------------------------------ASP-Active Ack)------>|
        |                                                    |

Note: If the SG detects loss of the M3UA peer (M3UA heartbeat loss or
detection of SCTP failure), the initial SG-ASP1 ASP Inactive message
exchange would not occur.

5.2.2 (1+1 Sparing, Back-up Over-ride)

Following on from the example in Section 4.1.2, 5.1.2, and ASP2 wishes to
over-ride ASP1 and take over the traffic:

       SG                       ASP1                       ASP2
        |                         |                          |
        |<------------------------------ ASP Active----------|
        |-------------------------------ASP-Active Ack------>|
        |----NTFY(Alt ASP-Act)--->|
        |                         |                          |

5.2.3 (n+k Sparing, Load-sharing case, withdrawal of ASP)

Following on from the example in Section 4.1.4, 5.1.4, and ASP1 withdraws from
service:

   SG                  ASP1                 ASP2                 ASP3
    |                    |                   |                   |
    |<----ASP Inact.-----|                   |                   |
    |---ASP-Inact Ack--->|                   |                   |
    |                    |                   |                   |
    |---------------------------------NTFY(Ins. ASPs)(Optional)->| ASPs)----------->|
    |                    |                   |                   |
    |<-----------------------------------------ASP Act (Ldshr)---|
    |-------------------------------------------ASP Act (Ack)--->|
    |                    |                   |                   |

The Notify message to ASP3 is optional, as well as

For the ASP-Active from
ASP3.  The optional Notify can only to occur if the SG maintains knowledge of the minimum ASP
resources required - for example if the SG knows that "n+k" = "2+1" for
a load-share AS and "n" currently equals "1".

Note: If the SG detects loss of the ASP1 M3UA peer (M3UA heartbeat loss
or detection of SCTP failure), the first SG-ASP1 ASP Inactive message
exchange would not occur.

5.3  M3UA/MTP3-User Boundary Examples

5.3.1 At an ASP

This section describes the primitive mapping from the MTP3 User to M3UA
at an ASP.

5.3.1.1 Support for MTP-Transfer on the ASP

5.3.1.1.1 Support for MTP-Transfer Request
When the MTP3-User on the ASP has data to send into the SS7 network, it
will use the MTP-Transfer Request primitive.  The M3UA on the ASP will
do the following when it receives an MTP-Transfer Request primitive
from the M3UA user:

  - Determine the correct SG

  - Determine the correct association to the chosen SG

  - Determine the correct stream in the association (e.g., based on
    SLS)

  - Determine whether to complete the optional fields of the Data
    message

  - Map the MTP-Transfer Request primitive into the Protocol Data
    field of an m3ua Data message

  - Send the Data message to the remote M3UA peer in the SG, over the
    SCTP association

        SG                       ASP
        |                         |
        |<-----Data Message-------|<--MTP-Transfer req.
        |                         |

5.3.1.1.2 Support for MTP Transfer Indication

When the M3UA on the ASP has received Data messages from the remote
M3UA peer in the SG it will do the following:

  - Evaluate the optional fields of the Data message if present

  - Map the Payload of a Data message into the MTP-Transfer Indication
    primitive

  - Pass the MTP-Transfer Indication primitive to the user part. In
    case of multiple user parts, the optional fields of the Data
    message are used to determine the concerned user part.

        SG                       ASP
        |                         |
        |------Data Message------>|---MTP-Transfer Message------>|-->MTP-Transfer ind.
        |                         |

5.3.1.1.3 Support for ASP Querying of SS7 Destination States

There are situations such as temporary loss of connectivity to the SG
that may cause the M3UA on the ASP to audit SS7 destination
availability states.  Note: there is no primitive for the MTP3-User to
request this audit from the M3UA as this is initiated by an internal
M3UA management function.

The M3UA on the ASP normally sends Destination State Audit (DAUD)
messages for each of the destinations that the ASP supports.

       SG                        ASP
        |                         |
        |<-----DAUD Message ------|
        |<-----DAUD Message ------|
        |<-----DAUD Message ------|
        |                         |
        |                         |

5.3.2 At an SG

This section describes the MTP3 upper layer primitive mapping to the
M3UA at the SG.

5.3.2.1 Support for MTP-Transfer Request at the SG

When the M3UA on the SG has received Data messages from its peer
destined to the SS7 network it will do the following:

  - Evaluate the optional fields of the Data message if present to
    determine the network appearance

  - Map the Protocol data of the Data message into an MTP-Transfer
    Request primitive

  - Pass the MTP-Transfer Request primitive to the MTP3 of the
    concerned network appearance.

                            SG                        ASP
                             |                         |
        <---MTP-Transfer req.|<------Data Message------|
                             |                         |

5.3.2.2 Support for MTP-Transfer Indication at the SG

When the MTP3 on the SG has data to pass its user parts, it will use
the MTP-Transfer Indication primitive.  The M3UA on the SG will do the
following when it receives an MTP-Transfer Indication:

  - Determine the correct ASP

  - Determine the correct association to the chosen ASP

  - Determine the correct stream in the association (e.g., based on
    SLS)

  - Determine whether to complete the optional fields of the Data
    message

  - Map the MTP-Transfer Indication primitive into the Protocol Data
    field of an M3UA Data message

  - Send the Data message to the remote M3UA peer in the ASP, over the
    SCTP association

                           SG                        ASP
                            |                         |
       --MTP-Transfer ind.->|------Data Message------>|
                            |                         |

5.3.2.3 Support for MTP-PAUSE, MTP-RESUME, MTP-STATUS

The MTP-PAUSE, MTP-RESUME and MTP-STATUS indication primitives from the
MTP3 upper layer interface at the SG need to be made available to the
remote MTP3 User Part lower layer interface at the concerned ASP(s).

5.3.2.3.1 Destination Unavailable

The MTP3 on the SG will generate an MTP-PAUSE primitive when it
determines locally that an SS7 destination is unreachable.  The M3UA
will map this primitive to a Destination Unavailable (DUNA) message.
The SG M3UA determines the set of concerned ASPs to be informed based
on internal SS7 network information associated with the MTP-PAUSE
primitive indication.

                   SG                       ASP
                    |                         |
 --MTP-PAUSE ind.-->|------DUNA Message ----->|--MTP-PAUSE ind.-->
                    |                         |

5.3.2.3.2 Destination Available

The MTP3 on the SG will generate an MTP-RESUME primitive when it
determines locally that an SS7 destination that was previously
unreachable is now reachable.  The M3UA will map this primitive to a
Destination Available (DAVA) message.  The SG M3UA determines the set
of concerned ASPs to be informed based on internal SS7 network
information associated with the MTP-RESUME primitive indication.

                   SG                       ASP
                    |                         |
--MTP-RESUME ind.-->|------DAVA Message ----->|--MTP-RESUME ind.-->
                    |                         |

5.3.2.3.3 SS7 Network Congestion

The MTP3 on the SG will generate an MTP-STATUS primitive when it
determines locally that the route to an SS7 destination is congested.
The M3UA will map this primitive to a SS7 Network Congestion State
(SCON) message.  It will determine which ASP(s) to send the DUPU to
based on the intended Application Server.

                     SG                       ASP
                       |                         |
   --MTP-STATUS ind.-->|------SCON Message ----->|--MTP-STATUS ind.-->
                       |                         |

5.3.2.3.4 Destination User Part Unavailable

The MTP3 on the SG will generate an MTP-STATUS primitive when it
receives an UPU message from the SS7 network.  The M3UA will map this
primitive to a Destination User Part Unavailable (DUPU) message.  It
will determine which ASP(s) to send the DUPU based on the intended
Application Server.

                      SG                       ASP
                       |                         |
   --MTP-STATUS ind.-->|------DUPU Message ----->|--MTP-STATUS ind.-->
                       |                         |

6.0 Security

6.1 Introduction

M3UA is designed to carry signalling messages for telephony services.
As such, M3UA must involve the security needs of several parties: the
end users of the services; the network providers and the applications
involved.  Additional requirements may come from local regulation.
While having some overlapping security needs, any security solution
should fulfill all of the different parties' needs.

6.2 Threats

There is no quick fix, one-size-fits-all solution for security.  As a
transport protocol, M3UA has the following security objectives:

 * Availability of reliable and timely user data transport.
 * Integrity of user data transport.
 * Confidentiality of user data.

M3UA runs on top of SCTP.  SCTP [6] provides certain transport related
security features, such as some protection against:

 * Blind Denial of Service Attacks
 * Flooding
 * Masquerade
 * Improper Monopolization of Services

When M3UA is running in professionally managed corporate or service
provider network, it is reasonable to expect that this network includes
an appropriate security policy framework. The "Site Security Handbook"
[21] should be consulted for guidance.

When the network in which M3UA runs in involves more than one party, it
may not be reasonable to expect that all parties have implemented
security in a sufficient manner.  In such a case, it is recommended
that IPSEC is used to ensure confidentiality of user payload.  Consult
[22] for more information on configuring IPSEC services.

6.3 Protecting Confidentiality

Particularly for mobile users, the requirement for confidentiality may
include the masking of IP addresses and ports.  In this case
application level encryption is not sufficient; IPSEC ESP should be
used instead.  Regardless of which level performs the encryption, the
IPSEC ISAKMP service should be used for key management.

7.0 IANA Considerations

7.1 SCTP Payload Protocol Identifier

A request will be made to IANA to assign an M3UA value for the Payload
Protocol Identifier in SCTP Payload Data chunk.  The following SCTP
Payload Protocol Identifier will be registered:

        M3UA    "3"

The SCTP Payload Protocol Identifier is included in each SCTP Data
chunk, to indicate which protocol the SCTP is carrying. This Payload
Protocol Identifier is not directly used by SCTP but MAY be used by
certain network entities to identify the type of information being
carried in a Data chunk.

The User Adaptation peer MAY use the Payload Protocol Identifier as a
way of determining additional information about the data being
presented to it by SCTP.

7.2 M3UA Protocol Extensions

This protocol may also be extended through IANA in three ways:
 -- through definition of additional message classes,
 -- through definition of additional message types, and
 -- through definition of additional message parameters

The definition and use of new message classes, types and parameters is
an integral part of SIGTRAN adaptation layers.  Thus these extensions
are assigned by IANA through an IETF Consensus action as defined in
[RFC2434].

The proposed extension must in no way adversely affect the general
working of the protocol.

7.2.1 IETF Defined Message Classes

The documentation for a new message class MUST include the following
information:
(a) A long and short name for the new message class;
(b) A detailed description of the purpose of the message class.

7.2.2 IETF Defined Message Types

The documentation for a new message type MUST include the following
information:
(a) A long and short name for the new message type;
(b) A detailed description of the structure of the message.
(c) A detailed definition and description of intended use for each
    field within the message.

(d) A detailed procedural description of the use of the new message
    type within the operation of the protocol.
(e) A detailed description of error conditions when receiving this
    message type.

When an implementation receives a message type which it does not
support, it MUST respond with an Error (ERR) message, with an Error
Code = Unsupported Message Type.

7.2.3 IETF-defined TLV Parameter extension

Documentation of the message parameter MUST contain the following
information:

(a) Name of the parameter type.
(b) Detailed description of the structure of the parameter field.  This
    structure MUST conform to the general type-length-value format
    described in Section 3.1.5.
(c) Detailed definition of each component of the parameter value.
(d) Detailed description of the intended use of this parameter type,
    and an indication of whether and under what circumstances multiple
    instances of this parameter type may be found within the same
    message.

8.0 Acknowledgements

The authors would like to thank John Loughney, Neil Olson, Michael
Tuexen, Nikhil Jain, Steve Lorusso, Dan Brendes, Joe Keller, Heinz
Prantner, Barry Nagelberg, Naoto Makinae Makinae, Selvam Rengasami, Shyamal
Prasad, Joyce Archibald, Ray Singh, Antonio Roque Alvarez and many
others for their valuable comments and suggestions.

9.0  References

[1] RFC 2719, "Framework Architecture for Signaling Transport"

[2] ITU-T Recommendations Q.761 to Q.767, 'Signalling System No.7 (SS7)
    - ISDN User Part (ISUP)'

[3] ANSI T1.113 - 'Signaling System Number 7 - ISDN User Part

[4] ETSI ETS 300 356-1 "Integrated Services Digital Network (ISDN);
    Signalling System No.7; ISDN User Part (ISUP) version 2 for the
    international interface; Part 1: Basic services"

[5] ITU-T Recommendations Q.711-715, 'Signalling System No. 7 (SS7) -
    Signalling Connection Control Part (SCCP)'

[6] ANSI T1.112 'Signaling System Number 7 - Signaling Connection
    Control Part'

[7] ETSI ETS 300 009-1, "Integrated Services Digital Network (ISDN);
    Signalling System No.7; Signalling Connection Control Part (SCCP)
    (connectionless and connection-oriented class 2) to support
    international interconnection; Part 1: Protocol specification"

[8] ITU-T Recommendations Q.720, 'Telephone User Part'

[9] ITU-T Recommendation Q.771-775 'Signalling System No. 7 SS7) -
    Transaction Capabilities (TCAP)

[10] ANSI T1.114 'Signaling System Number 7 - Transaction Capabilities
     Application Part'

[11] ETSI ETS 300 287-1, "Integrated Services Digital Network (ISDN);
     Signalling System No.7; Transaction Capabilities (TC) version 2;
     Part 1: Protocol specification"

[12] 3G TS 25.410 V3.1.0 (2000-01) Technical Specification - 3rd
     Generation partnership Project; Technical Specification Group
     Radio Access Network; UTRAN Iu Interface: General Aspects and
     Principles (3G TS 25.410 Version 3.1.0 Release 1999)

[13] RFC 2719, 2960, "Stream Control Transport Protocol", R. Stewart et al,
     October 2000.

[14] ITU-T Recommendations Q.701-Q.705, 'Signalling System No. 7 (SS7)
     - Message Transfer Part (MTP)'

[15] ANSI T1.111 'Signaling System Number 7 - Message Transfer Part'

[16] ETSI ETS 300 008-1, "Integrated Services Digital Network (ISDN);
     Signalling System No.7; Message Transfer Part (MTP) to support
     international interconnection; Part 1: Protocol specification"

[17] ITU-T Recommendation Q.2140 'B-ISDN ATM Adaptation Layer - Service
     Specific Coordination Function for signalling at the Network Node
     Interface (SSCF at NNI)

[18] ITU-T Recommendation Q.2110 'B-ISDN ATM Adaptation Layer - Service
     Specific Connection Oriented Protocol (SSCOP)

[19] MTP2-User Adaptation Layer <draft-ietf-sigtran-m2ua-01.txt>, <draft-ietf-sigtran-m2ua-05.txt>, Nov.
     1999,
     2000, Work in Progress

[20] ITU-T Recommendation Q.2210 'B-ISDN MTP'

[21] RFC 2196, "Site Security Handbook", B. Fraser Ed., September 1997

[22] RFC 2401, "Security Architecture for the Internet Protocol", S.
Kent, R. Atkinson, November 1998.

10.0  Author's Addresses

Greg Sidebottom
Nortel Networks
3685 Richmond Rd,
Nepean, Ontario, Canada  K2H 5B7
gregside@nortelnetworks.com

Guy Mousseau
Nortel Networks
3685 Richmond Rd
Nepean, Ontario, Canada  K2H 5B7

Lyndon Ong
Nortel
Point Reyes Networks
4401 Great America Pkwy
Santa Clara,
1991 Concourse Dr.
San Jose, CA, USA  95054
long@nortelnetworks.com  95131
long@pointreyesnet.com

Ian Rytina
Ericsson Australia
37/360 Elizabeth Street
Melbourne, Victoria 3000, Australia
ian.rytina@ericsson.com

Hanns Juergen Schwarzbauer
SIEMENS AG
Hofmannstr. 51
81359 Munich, Germany
HannsJuergen.Schwarzbauer@icn.siemens.de

Klaus D. Gradischnig
SIEMENS AG
Hofmannstr. 51
81359 Munich, Germany
klaus.gradischnig@icn.siemens.de

Ken Morneault
Cisco Systems Inc.
13615 Dulles Technology Drive
Herndon, VA, USA  20171
EMail: kmorneau@cisco.com

Malleswar Kalla
Telcordia Technologies
MCC 1J211R
445 South Street
Morristown, NJ, USA  07960
Email: kalla@research.telcordia.com

Normand Glaude
Performance Technologies
150 Metcalf Sreet, Suite 1300
Ottawa, Ontario, Canada  K2P 1P1
EMail: nglaude@microlegend.com

This draft expires May 2000. August 2001.