draft-ietf-sigtran-m3ua-01.txt   draft-ietf-sigtran-m3ua-02.txt 
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INTERNET-DRAFT Nortel Networks INTERNET-DRAFT Nortel Networks
Ian Rytina Ian Rytina
Ericsson Ericsson
Hanns-Juergen Schwarzbauer Hanns-Juergen Schwarzbauer
Siemens Siemens
Ken Morneault Ken Morneault
Cisco Cisco
Mallesh Kalla Mallesh Kalla
Telcordia Telcordia
Expires in six months 15 February 2000 Expires in six months 10 March 2000
SS7 MTP3-User Adaptation Layer (M3UA) SS7 MTP3-User Adaptation Layer (M3UA)
<draft-ietf-sigtran-m3ua-01.txt> <draft-ietf-sigtran-m3ua-02.txt>
Status of This Memo Status of This Memo
This document is an Internet-Draft and is in full conformance with all This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC 2026. Internet-Drafts are working provisions of Section 10 of RFC 2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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Simple Control Transport Protocol. Also, provision is made for Simple Control Transport Protocol. Also, provision is made for
protocol elements that enable a seamless operation of the MTP3-User 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 peers in the SS7 and IP domains. This protocol would be used between a
Signaling Gateway (SG) and a Media Gateway Controller (MGC) or IP- Signaling Gateway (SG) and a Media Gateway Controller (MGC) or IP-
resident Database. It is assumed that the SG receives SS7 signaling resident Database. It is assumed that the SG receives SS7 signaling
over a standard SS7 interface using the SS7 Message Transfer Part (MTP) over a standard SS7 interface using the SS7 Message Transfer Part (MTP)
to provide transport. to provide transport.
TABLE OF CONTENTS TABLE OF CONTENTS
1. Introduction..............................................3 1. Introduction.......................................................3
2. Protocol Elements........................................11 1.1 Scope.........................................................3
3. Procedures...............................................21 1.2 Terminology...................................................5
4. Examples.................................................26 1.3 Signalling Transport Architecture.............................5
5. Security.................................................27 1.4 Services Provided by the M3UA Layer..........................13
6. Acknowledgements.........................................27 1.5 Internal Functions in the M3UA...............................15
7. References...............................................27 1.6 Definition of M3UA Boundaries................................18
8. Author's Addresses.......................................28 2. M3UA Protocol Elements............................................18
2.1 Common Message Header........................................19
2.2 Transfer Messages............................................20
2.3 SS7 Signaling Network management (SSNM) Messages.............21
2.4 Application Server Process Maintenance Messages..............27
2.5 Management Messages..........................................31
3. Procedures........................................................34
3.1 Procedures to Support the Services of the M3UA Layer.........34
3.2 Procedures to Support the M3UA Services in Section 1.4.2.....34
3.3 Procedures to Support the M3UA Services in Section 1.4.4.....35
3.4 Procedures to Support the M3UA Services in Section 1.4.3.....43
4. Examples of M3UA Procedures.......................................45
4.1 Establishment of Association and Traffic
Between SGs and ASPs.........................................45
4.2 ASP traffic Failover Examples................................47
4.3 M3UA/MTP3-User Boundary Examples.............................48
5. Security..........................................................52
5.1 Introduction.................................................52
5.2 Threats......................................................52
5.3 Protecting Confidentiality...................................53
6. IANA Considerations...............................................53
7. Acknowledgements..................................................53
8. References........................................................53
9. Author's Addresses................................................55
1. Introduction 1. Introduction
1.1 Scope 1.1 Scope
There is a need for SCN signaling protocol delivery from an SS7 There is a need for SCN signaling protocol delivery from an SS7
Signaling Gateway (SG) to a Media Gateway Controller (MGC) or IP- Signaling Gateway (SG) to a Media Gateway Controller (MGC) or IP-
resident Database as described in the Framework Architecture for resident Database as described in the Framework Architecture for
Signalling Transport [1]. The delivery mechanism should meet the Signalling Transport [1]. The delivery mechanism should meet the
following criteria: following criteria:
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* Support for the asynchronous reporting of status changes to * Support for the asynchronous reporting of status changes to
management management
In simplistic terms, the SG will terminate SS7 MTP2 and MTP3 protocols In simplistic terms, the SG will terminate SS7 MTP2 and MTP3 protocols
and deliver ISUP, SCCP and/or any other MTP3-User protocol messages and deliver ISUP, SCCP and/or any other MTP3-User protocol messages
over SCTP transport associations to MTP3-User peers in MGCs or IP- over SCTP transport associations to MTP3-User peers in MGCs or IP-
resident Databases. resident Databases.
1.2 Terminology 1.2 Terminology
Application Node (AN) - A physical node in an IP network (i.e., an MGCU Application Server (AS) - A logical entity serving a specific Routing
or Database node), with one or more unique IP network addresses. An AN Key. An example of an Application Server is a virtual switch element
supports one or more SCTP end-points and one or more Application Server handling all call processing for a unique range of PSTN trunks,
Processes. identified by an SS7 DPC/OPC/CIC_range. Another example is a virtual
database element, handling all HLR transactions for a particular SS7
Application Server (AS) - A logical entity serving a specific DPC/OPC/SCCP_SSN combination. The AS contains a set of one or more
application instance. An example of an Application Server is a virtual unique Application Server Processes, of which one or more is normally
switch element handling all call processing for a unique range of PSTN actively processing traffic.
trunks, identified by an SS7 DPC/OPC/CIC_range. Practically speaking,
an AS is modeled at the SG as an ordered list 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 Application Server Process (ASP) - A process instance of an Application
Server. An Application Server Process serves as an active or standby Server. An Application Server Process serves as an active or standby
process of an Application Server (e.g., part of a distributed virtual process of an Application Server (e.g., part of a distributed virtual
switch or database element). switch or database element). 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 - An association refers to an SCTP association. The
association provides the transport for the delivery of MTP3-User association provides the transport for the delivery of MTP3-User
protocol data units and M3UA adaptation layer peer messages. protocol data units and M3UA adaptation layer peer messages.
Routing Key: At the SG, the Routing Key describes a set of SS7
parameter/parameter-ranges that uniquely defines the range of
signalling traffic configured to be handled by a particular Application
Server. For example, where all traffic directed to a particular 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 mutually exclusive in 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 ranges within a
particular Routing Key to be contiguous. For example, an ASP could be
configured to support call processing for multiple ranges of PSTN
trunks that are not represented by contiguous CIC values.
Routing Context An Application Server Process may be configured to
process traffic within more than one Application Server. In this case,
the Routing Context parameter is exchanged beween the SG and the ASP,
identifying the relevant Application Server. From the perspective of
an ASP, the Routing Context uniquely identifies the range of traffic
associated with a particular Application Server, which the ASP is
configured to receive from the SG. There is a 1:1 relationship between
a Routing Context value and a Routing Key at an SG. Therefore the
Routing Context can be viewed as an index into an SG Table containing
the SG Routing Keys.
Fail-over - The capability to re-route signaling traffic as required to Fail-over - The capability to re-route signaling traffic as required to
an alternate Application Server Process, or group of ASPs, within an an alternate Application Server Process, or group of ASPs, within an
Application Server in the event of failure or unavailability of a Application Server in the event of failure or unavailability of a
currently used Application Server Process. Fail-back may apply upon currently used Application Server Process. Fail-back may apply upon
the return to service of a previously unavailable Application Server the return to service of a previously unavailable Application Server
Process. Process.
IP Database - The IP-resident analogue of a PSTN Service Control Point Signalling Point Management Cluster (SPMC) A complete set of
(SCP) or wireless Home Location Register (HLR). Application Servers represented to the SS7 network under the same SS7
Point Code. SPMCs are used to sum the
MTP3 Management Cluster (MMC) - A group of one or more Application availability/congestion/User_Part status of an SS7 destination point
Servers represented to the SS7 network under the same SS7 Destination code that is distributed in the IP domain, for the purpose of
Point Code. MMCs are used to sum the availability/congestion status of supporting MTP3 management procedures at an SG. In some cases, the SG
an SS7 destination that is distributed in the IP domain, for the itself may also be a member of the SPMC. In this case, the SG
purpose of supporting MTP Level 3 management procedures. availability/congestion/User_Part status must also be taken into
account when considering any supporting MTP3 management actions.
MTP3-User - Any protocol normally using the services of the SS7 MTP3 MTP3-User - Any protocol normally using the services of the SS7 MTP3
(e.g., ISUP, SCCP, TUP, etc.). (e.g., ISUP, SCCP, TUP, etc.).
Network Appearance - The Network Appearance identifies the SS7 network Network Appearance The Network Appearance identifies an SS7 network
context for the purposes of logically separating the signaling traffic context for the purposes of logically separating the signaling traffic
between the SG and the Application Server Processes over common SCTP between the SG and the Application Server Processes over a common SCTP
Associations. An example is where an SG is logically partitioned to Association. An example is where an SG is logically partitioned to
appear as an element in four separate SS7 national networks. A Network appear as an element in four separate national SS7 networks. A Network
Appearance uniquely defines the SS7 Destination Point Code, Network Appearance implicitly defines the SS7 Point Code(s), Network Indicator
Indicator and MTP3 protocol type/variant/version used within each and MTP3 protocol type/variant/version used within a specific SS7
network. An SS7 route-set or link-set at an SG can appear in only one
network appearance. network partition. An 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.
Network Byte Order: Most significant byte first, a.k.a Big Endian. Network Byte Order: Most significant byte first, a.k.a Big Endian.
Routing Context - An Application Server Process may be configured to Layer Management Layer Management is a nodal function in an SG or ASP
process traffic within more than one Application Server. From the that handles the inputs and outputs between the M3UA layer and a local
perspective of an ASP, a Routing Context defines a range of signaling management entity.
traffic that the ASP is currently configured to receive from the SG.
For example, an ASP could be configured to support call processing for Host - The computing platform that the ASP process is running on.
multiple ranges of PSTN trunks and therefore receive related signaling
traffic, identified by separate SS7 DPC/OPC/CIC_ranges.
Stream - A stream refers to an SCTP stream. Stream - A stream refers to an SCTP stream.
1.3 Signaling Transport Architecture 1.3 Signaling Transport Architecture
1.3.1 Protocol Architecture. 1.3.1 Protocol Architecture.
The framework architecture that has been defined for SCN signaling The framework architecture that has been defined for SCN signaling
transport over IP [1] uses multiple components, including a signaling transport over IP [1] uses multiple components, including a signaling
common transport protocol and an adaptation module to support the common transport protocol and an adaptation module to support the
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adaptation module that is suitable for the transport of SS7 ISDN User adaptation module that is suitable for the transport of SS7 ISDN User
Part (ISUP) [2,3,4] and Signalling Connection Control Part (SCCP) Part (ISUP) [2,3,4] and Signalling Connection Control Part (SCCP)
[5,6,7] messages but could be equally used to transport other SS7 MTP3- [5,6,7] messages but could be equally used to transport other SS7 MTP3-
User Part messages such as, for example, the Telephone User Part (TUP) User Part messages such as, for example, the Telephone User Part (TUP)
[8]. TCAP [9,10,11] or RANAP [12] messages are transported [8]. TCAP [9,10,11] or RANAP [12] messages are transported
transparently by the M3UA as SCCP payload, as they are SCCP-User transparently by the M3UA as SCCP payload, as they are SCCP-User
protocols. The M3UA uses the services of the Simple Common Transport protocols. The M3UA uses the services of the Simple Common Transport
protocol [13] as the underlying reliable signaling common transport protocol [13] as the underlying reliable signaling common transport
protocol. protocol.
In a Signaling Gateway, it is expected that the SS7 ISUP/SCCP signaling In a Signaling Gateway, it is expected that the SS7 MTP3-User signaling
is transmitted and received from the PSTN over a standard SS7 network is transmitted and received from the PSTN over a standard SS7 network
interface, using the SS7 Message Transfer Part (MTP) [14,15,16] to interface, using the SS7 Message Transfer Part (MTP) [14,15,16] to
provide reliable transport of the ISUP/SCCP signaling messages to and provide reliable transport of the MTP3-User signaling messages to and
from an SS7 Signaling End Point (SEP) or Signaling Transfer Point from an SS7 Signaling End Point (SEP) or Signaling Transfer Point
(STP). The SG then provides a functional inter-working of transport (STP). The SG then provides a functional inter-working of transport
functions with the IP transport, in order to transfer the ISUP/SCCP functions with the IP transport, in order to transfer the MTP3-User
signaling messages to and from an Application Server Process where the signaling messages to and from an Application Server Process where the
peer ISUP/SCCP protocol layer exists. peer MTP3-User protocol layer exists.
The use of standard MTP Level 2 signaling links in the SS7 network The use of standard MTP Level 2 signaling links in the SS7 network
interface is not the only possibility. ATM-based High Speed Links interface is not the only possibility. ATM-based High Speed Links
could also be used, using the services of the Signaling ATM Adaptation could also be used, using the services of the Signaling ATM Adaptation
Layer (SAAL) [17,18]. For that matter, it is possible that IP-based Layer (SAAL) [17,18]. For that matter, it is possible that IP-based
links could be present, using the services of the MTP2-User Adaptation links could be present, using the services of the MTP2-User Adaptation
Layer (M2UA) [19]. Also note that STPs may be present in the SS7 path Layer (M2UA) [19]. Also note that STPs may be present in the SS7 path
between the SS7 SEP and the SG. between the SS7 SEP and the SG.
Where ATM-base High Speed Links are used in the SS7 network, it is Where ATM-base High Speed Links are used in the SS7 network, it is
possible for the SG to use the services of the MTP-3b [20] for reliable possible for the SG to use the services of the MTP-3b [20] for reliable
transport to and from an SS7 SEP or STP. The maximum Service Data Unit transport to and from an SS7 SEP or STP. The maximum Service Data Unit
(SDU) supported by the MTP-3b is 4096 octets compared to the 272 octet (SDU) supported by the MTP-3b is 4096 octets compared to the 272 octet
maximum of the MTP. However, for MTP3-Users to take advantage of the maximum of the MTP. However, for MTP3-Users to take advantage of the
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transport to and from an SS7 SEP or STP. The maximum Service Data Unit transport to and from an SS7 SEP or STP. The maximum Service Data Unit
(SDU) supported by the MTP-3b is 4096 octets compared to the 272 octet (SDU) supported by the MTP-3b is 4096 octets compared to the 272 octet
maximum of the MTP. However, for MTP3-Users to take advantage of the maximum of the MTP. However, for MTP3-Users to take advantage of the
larger SDU between MTP3-User peers, network architects should ensure 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 that MTP3-b is used end-to-end between the SG and the SS7-resident
peer. peer.
Three example cases are shown below: Three example cases are shown below:
1.3.1.1 Example 1: ISUP transport 1.3.1.1 Example 1: ISUP transport
******** SS7 ***************** IP ******** ******** SS7 ***************** IP ********
* SEP *---------* SG *--------* ASP * * SEP *---------* SG *--------* ASP *
******** ***************** ******** ******** ***************** ********
+------+ +------+ +------+ +------+
| ISUP | | ISUP | | ISUP | (NIF) | ISUP |
+------+ +------+-+------+ +------+ +------+ +------+-+------+ +------+
| MTP3 | | MTP3 | | M3UA | | M3UA | | MTP3 | | MTP3 | | M3UA | | M3UA |
+------| +------+ +------+ +------+ +------| +------+ +------+ +------+
| MTP2 | | MTP2 | | SCTP | | SCTP | | MTP2 | | MTP2 | | SCTP | | SCTP |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| L1 | | L1 | | UDP | | UDP | | L1 | | L1 | | IP | | IP |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
|_______________| |______________| |_______________| |______________|
SEP - SS7 Signaling End Point SEP - SS7 Signaling End Point
SCTP - Simple Control Transport Protocol SCTP - Simple Common Transport Protocol
NIF Nodal Interworking Function
Within the SG, MTP-TRANSFER indication primitives received from the MTP Within the SG, MTP-TRANSFER indication primitives received from the MTP
Level 3 upper layer interface are sent to the local M3UA-resident Level 3 upper layer interface are sent to the local M3UA-resident
network address translation and mapping function for ongoing routing to network address translation and mapping function for ongoing routing to
the final IP destination. MTP-TRANSFER primitives received from the the final IP destination. MTP-TRANSFER primitives received from the
local M3UA network address translation and mapping function are sent to local M3UA network address translation and mapping function are sent to
the MTP Level 3 upper layer interface as MTP-TRANSFER request the MTP Level 3 upper layer interface as MTP-TRANSFER request
primitives for on-going MTP Level 3 routing to an SS7 SEP. primitives for on-going MTP Level 3 routing to an SS7 SEP.
For internal SG modelling purposes, this may be accomplished with the For internal SG modelling purposes, this may be accomplished with the
use of an implementation-dependent nodal inter-working function within use of an implementation-dependent nodal inter-working function within
the SG that serves as a local user of the MTP3 and M3UA. This nodal the SG that serves to transport messages within the SG between the MTP3
inter-working function has no visible peer protocol with either the ASP and M3UA. This nodal inter-working function has no visible peer
or SEP. protocol with either the ASP or SEP.
1.3.1.2 Example 2: SCCP transport where an SCCP function at the SG is 1.3.1.2 Example 2: SCCP transport where an SCCP function at the SG is
invoked: invoked:
******** SS7 ***************** IP ******** ******** SS7 ***************** IP ********
* SEP *---------* *--------* * * SEP *---------* *--------* *
* or * * SG * * ASP * * or * * SG * * ASP *
* STP * * * * * * STP * * * * *
******** ***************** ******** ******** ***************** ********
+------+ +---------------+ +------+ +------+ +---------------+ +------+
| SCCP | | SCCP | | SCCP | | SCCP | | SCCP | | SCCP |
+------+ +------+-+------+ +------+ +------+ +------+-+------+ +------+
| MTP3 | | MTP3 | | M3UA | | M3UA | | MTP3 | | MTP3 | | M3UA | | M3UA |
+------| +------+ +------+ +------+ +------| +------+ +------+ +------+
| MTP2 | | MTP2 | | SCTP | | SCTP | | MTP2 | | MTP2 | | SCTP | | SCTP |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| L1 | | L1 | | UDP | | UDP | | L1 | | L1 | | IP | | IP |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
|_______________| |______________| |_______________| |______________|
STP - SS7 Signaling Transfer Point STP - SS7 Signaling Transfer Point
In this example, the SG contains an instance of the SS7 SCCP protocol In this example, the SG contains an instance of the SS7 SCCP protocol
layer that may, for example, perform the SCCP Global Title Translation layer that may, for example, perform the SCCP Global Title Translation
(GTT) function for messages logically addressed to the SG SCCP. If the (GTT) function for messages logically addressed to the SG SCCP. If the
result of a GTT for an SCCP message yields an SS7 DPC or DPC/SSN result of a GTT for an SCCP message yields an SS7 DPC or DPC/SSN
address result of an SCCP peer located in the IP domain, the resulting address result of an SCCP peer located in the IP domain, the resulting
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the SG that effectively sits below the SCCP and routes MTP-TRANSFER 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 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 DPC/SSN address information. This nodal inter-working function has no
visible peer protocol with either the ASP or SEP. visible peer protocol with either the ASP or SEP.
Note that the services and interface provided by M3UA are the same as Note that the services and interface provided by M3UA are the same as
in Example 1 and the functions taking place in the SCCP entity are in Example 1 and the functions taking place in the SCCP entity are
transparent to M3UA. The SCCP protocol functions are not reproduced in transparent to M3UA. The SCCP protocol functions are not reproduced in
the M3UA protocol. the M3UA protocol.
1.3.1.3 Example 3 - Seamless Handling of MTP3 Management 1.3.1.3 Example 3 Seamless Handling of MTP3 Management
******** SS7 ***************** IP ******** ******** SS7 ***************** IP ********
* SEP *---------* *--------* * * SEP *---------* *--------* *
* or * * SG * * ASP * * or * * SG * * ASP *
* STP * * * * * * STP * * * * *
******** ***************** ******** ******** ***************** ********
(NIF)
+------+ +------+-+------+ +------+ +------+ +------+-+------+ +------+
| MTP3 | | MTP3 | | M3UA | | M3UA | | MTP3 | | MTP3 | | M3UA | | M3UA |
+------| +------+ +------+ +------+ +------| +------+ +------+ +------+
| MTP2 | | MTP2 | | SCTP | | SCTP | | MTP2 | | MTP2 | | SCTP | | SCTP |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| L1 | | L1 | | UDP | | UDP | | L1 | | L1 | | IP | | IP |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
|_______________| |______________| |_______________| |______________|
In the case of SS7 MTP3 network management, it is required that the In the case of SS7 MTP3 network management, it is required that the
MTP3-User protocols at ASPs receive indications of SS7 signaling point MTP3-User protocols at ASPs receive indications of SS7 signaling point
availability, SS7 network congestion and User Part availability as availability, SS7 network congestion and User Part availability as
would be expected an SS7 SEP node. To accomplish this, the MTP-PAUSE, would be expected an SS7 SEP node. To accomplish this, the MTP-PAUSE,
MTP-RESUME and MTP-STATUS indication primitives received at the MTP3 MTP-RESUME and MTP-STATUS indication primitives received at the MTP3
upper layer interface at the SG need to be made available to the remote upper layer interface at the SG need to be made available to the remote
MTP3-User lower layer interface at the AN. Note: These indication MTP3-User lower layer interface at the ASP. Note: These indication
primitives are also made available to any existing local MTP3-Users at primitives are also made available to any existing local MTP3-Users at
the SG, such as the SCCP in the previous example. the SG, such as the SCCP in the previous example.
For internal SG modelling purposes, this may be accomplished with the For internal SG modelling purposes, this may be accomplished with the
use of an implementation-dependent nodal inter-working function within use of an implementation-dependent nodal inter-working function within
the SG that effectively sits above the MTP3 and delivers MTP-PAUSE, the SG that effectively sits above the MTP3 and delivers MTP-PAUSE,
MTP-RESUME and MTP-STATUS indication primitives received from the MTP MTP-RESUME and MTP-STATUS indication primitives received from the MTP
Level 3 upper layer interface to the local M3UA-resident management Level 3 upper layer interface to the local M3UA-resident management
function. This nodal inter-working function has no visible peer function. This nodal inter-working function has no visible peer
protocol with either the ASP or SEP. protocol with either the ASP or SEP.
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blindly to the ASPs. Rather, the existing MTP3 management procedures blindly to the ASPs. Rather, the existing MTP3 management procedures
are followed within the MTP3 function of the SG to re-calculate the are followed within the MTP3 function of the SG to re-calculate the
MTP3 route set status and initiate any signaling-route-set-test MTP3 route set status and initiate any signaling-route-set-test
procedures into the SS7 network. Only when a route set status changes procedures into the SS7 network. Only when a route set status changes
are MTP-PAUSE or MTP-RESUME primitives invoked. These primitives can are MTP-PAUSE or MTP-RESUME primitives invoked. These primitives can
also be invoked due to local SS7 link set conditions as per existing also be invoked due to local SS7 link set conditions as per existing
MTP3 procedures. MTP3 procedures.
1.3.2 Signaling Network Architecture 1.3.2 Signaling Network Architecture
A Signaling Gateway is used to support the transport of ISUP/SCCP A Signaling Gateway is used to support the transport of MTP3-User
signaling traffic received from the SS7 network to multiple distributed signaling traffic received from the SS7 network to multiple distributed
Application Nodes (e.g., MGCUs and IP Databases). Clearly, an SG-ASP ASPs (e.g., MGCs and IP Databases). Clearly, the M3UA protocol
protocol description cannot in itself meet any performance and description cannot in itself meet any performance and reliability
reliability requirements for such transport. A physical network requirements for such transport. A physical network architecture is
architecture is required, with data on the availability and transfer required, with data on the availability and transfer performance of the
performance of the physical nodes involved in any particular exchange physical nodes involved in any particular exchange of information.
of information. The protocol used must simply be flexible enough allow However, the M3UA protocol must be flexible enough allow its operation
its operation and management in a variety of physical configurations and management in a variety of physical configurations that will enable
that will enable Network Operators to meet their performance and Network Operators to meet their performance and reliability
reliability requirements. requirements.
To meet the stringent SS7 signaling reliability and performance To meet the stringent SS7 signaling reliability and performance
requirements for carrier grade networks, these Network Operators should requirements for carrier grade networks, these Network Operators should
ensure that there is no single point of failure provisioned in the end- ensure that there is no single point of failure provisioned in the end-
to-end network architecture between an SS7 SEP and an IP Application to-end network architecture between an SS7 node and an IP ASP.
Node. Depending of course on the reliability of the SG and AN Depending of course on the reliability of the SG and ASP functional
functional elements, this can typically be met by the use of redundant elements, this can typically be met by the use of redundant SGs, the
SGs, the provision of redundant QOS-bounded IP network paths for SCTP provision of redundant QOS-bounded IP network paths for SCTP
Associations between SCTP End Points, and redundant Application Nodes. Associations between SCTP End Points, and redundant Hosts. The
The distribution of ASPs within the available Application Nodes is also distribution of ASPs within the available Hosts is also important. For
a particular Application Server, the related ASPs should be distributed
important. For a particular Application Server, the related ASPs over at least two Hosts.
should be distributed over at least two physical Application Nodes.
An example physical network architecture relevant to carrier-grade An example physical network architecture relevant to carrier-grade
operation in the IP network domain is shown in Figure 1 below: operation in the IP network domain is shown in Figure 1 below:
******** ************** ******** **************
* *__________________________________________* ******** * AN1 * *_________________________________________* ******** * Host1
* * * * ASP1 * * * * _________* * ASP1 * *
* SG1 * SCTP Associations * ******** * * SG1 * SCTP Associations | * ******** *
* *_______________________ * ******** * * *_______________________ | * ******** *
* * | * * ASP2 * * * * | | * * ASP2 * *
* * | * ******** * * * | | * ******** *
* * | * ******** * * * | | * ******** *
* * | * * ASP3 * * * * | | * * ASP3 * *
******** | * ******** * ******** | | * ******** *
| * . * | | * . *
******** | * . * ******** | | * . *
* *------------------------------------------* * * *_______________________________| * *
* * | * ******** * * * | * ******** *
* SG2 * SCTP Associations | * * ASPn * * * SG2 * SCTP Associations | * * ASPn * *
* *____________ | * ******** * * *____________ | * ******** *
* * | | ************** * * | | **************
* * | | ************** * * | | **************
* * | |__________________* ******** * AN2 * * | |_________________* ******** * Host2
* * | * * ASP1 * * * * |____________________________* * ASP1 * *
******** | * ******** * ******** * ******** *
|_____________________________* ******** * * ******** *
* * ASP2 * * * * ASP2 * *
* ******** * * ******** *
* ******** * * ******** *
* * ASP3 * * * * ASP3 * *
* ******** * * ******** *
* . * * . *
* . * * . *
* * * *
* ******** * * ******** *
* * ASPn * * * * ASPn * *
* ******** * * ******** *
************** **************
. .
. .
. .
Figure 1 - Physical Model Figure 1 Physical Model
For carrier grade networks, Operators should ensure that under failure For carrier grade networks, Operators should ensure that under failure
or isolation of a particular AN, stable calls or transactions are not or isolation of a particular ASP, stable calls or transactions are not
lost. This implies that Application Nodes need, in some cases, to lost. This implies that ASPs need, in some cases, to share the
call/transaction state or be able to pass the call/transaction state
share the call/transaction state or be able to pass the between each other. Also, in the case of ASPs performing call
call/transaction state between each other. Also, in the case of MGC processing, coordination may be required with the related Media Gateway
Application Nodes, coordination may be required with the related Media to transfer the MGC control for a particular trunk termination.
Gateway to transfer the MGC control for a particular trunk termination.
However, this sharing or communication is outside the scope of this However, this sharing or communication is outside the scope of this
document. document.
1.3.3 SS7 Point Code Representation 1.3.3 SS7 Point Code Representation
A Signaling Gateway is charged with representing the IP network nodes Within an SS7 network, a Signaling Gateway is charged with representing
into the SS7 network for routing purposes. The SG itself, as a a set of nodes in the IP domain into the SS7 network for routing
physical node in the SS7 network, must be addressable with an SS7 purposes. The SG itself, as a physical node in the SS7 network, must
Destination Point Code for MTP3 Management purposes. This DPC will be addressable with an SS7 Point Code for MTP3 Management purposes.
also be used to address any local MTP3-Users such as an SG-resident The SG Point Code will also be used for addressing any local MTP3-Users
SCCP function. An SG may also be addressable with multiple DPCs where at the SG such as an SG-resident SCCP function.
the SG is logically partitioned to operate in multiple SS7 network
appearances. Alias DPCs may also be used within an SG or an SG network Where an SG is logically partitioned to operate in multiple SS7 network
appearances, 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 may also be used within an SG network
appearance, but SG MTP3 management messages to/from the SS7 network appearance, but SG MTP3 management messages to/from the SS7 network
will not use the alias DPCs. will not use the alias PCs.
The M3UA places no restrictions on the SS7 Destination Point Code (DPC) The M3UA places no restrictions on the SS7 Point Code representation of
representation of any of the ASPs. ASPs can be represented under the any of the ASPs. ASPs can be represented under the same PC of the SG,
same DPC of the SG, their own individual Destination Point Codes (DPCs) their own individual Point Codes or grouped with other ASPs for Point
or grouped with other ASPs for Point Code preservation purposes. A Code preservation purposes. A single Point Code may be used to
single DPC may be used for the SG and all the ASPs together, if represent the SG and all the ASPs together, if desired.
desired. Note: there are potential SS7 traffic engineering
restrictions in some arrangements as there is a maximum number of SS7
links within a unique link-set to an adjacent SS7 node.
If an ASP or group of ASPs is available to the SS7 network via more If an ASP or group of ASPs is available to the SS7 network via more
than one SG, it is recommended that the ASP(s) be represented by a than one SG, each with its own Point Code, the ASP(s) can be
Destination Point Code that is separate from any SG DPC. This allows represented by a Point Code that is separate from any SG Point Code.
some SGs to be viewed from the SS7 network as "STPs", each having a This allows these SGs to be viewed from the SS7 network as "STPs", each
"route" to the same ASP. Under failure conditions where an ASP becomes having an ongoing "route" to the same ASP(s). Under failure
unavailable from one of the SGs, this approach enables MTP3 route conditions where an ASP becomes unavailable from one of the SGs, this
management messaging between the SG and SS7 network, allowing simple approach enables MTP3 route management messaging between the SG and SS7
re-routing through an alternate SG. network, allowing simple SS7 re-routing through an alternate SG without
changing the Destination Point Code Address of SS7 traffic to the ASPs.
+--------+
| |
+------------+ SG 1 +--------------+
+-------+ | | "STP" | | ----
| 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.
1.3.4 ASP Fail-over Model and Terminology 1.3.4 ASP Fail-over Model and Terminology
The network address translation and mapping function of the M3UA The network address translation and mapping function of the M3UA
supports ASP fail-over functions in order to support a high supports ASP fail-over functions in order to support a high
availability of call and transaction processing capability. All availability of call and transaction processing capability. All MTP3-
ISUP/SCCP messages incoming to an SG from the SS7 network are assigned User messages (e.g., ISUP, SCCP) incoming to an SG from the SS7 network
to a unique Application Server, based on the information in the are assigned to a unique Application Server, based on the information
message. The information examined may be one or more of the MTP DPC, in the message. The information examined may be one or more of the MTP
OPC, SLS, or any MTP3-User specific fields such as, for example, the DPC, OPC, SLS, or any MTP3-User specific fields such as, for example,
ISUP CIC, SCCP SSN, or TCAP TRID. Some example possibilities are the the ISUP CIC, SCCP SSN, or TCAP TRID. Some example possibilities are
DPC alone, the DPC/OPC combination, the DPC/OPC/CIC combination, or the the DPC alone, the DPC/OPC combination, the DPC/OPC/CIC combination, or
DPC/SSN combination. The information used to point to an AS is not the DPC/SSN combination. The information used to point to an AS is not
limited by the M3UA and none of the examples are mandated. limited by the M3UA and none of the examples are mandated.
The Application Server is in practical terms an ordered list of all The Application Server is in practical terms a list of all ASPs
ASPs configured/registered to process ISUP/SCCP messages within a currently configured/registered to process MTP3-User messages within a
certain range of routing information, known as a Routing Key. One or certain range of routing information, known as a Routing Key. One or
more ASPs in the list are normally handling traffic while any others more ASPs in the list are normally active (i.e., handling traffic)
are inactive but available in the event of failure or unavailability of while any others may be unavailable or inactive, to be possibly used in
the active ASP(s). the event of failure or unavailability of the active ASP(s).
The fail-over model supports an "n+k" redundancy model, where "n" ASPs The fail-over model supports an "n+k" redundancy model, where "n" ASPs
is the minimum number of redundant ASPs required to handle traffic and is the minimum number of redundant ASPs required to handle traffic and
"k" ASPs are available to take over for a failed or unavailable ASP. "k" ASPs are available to take over for a failed or unavailable ASP.
Note that "1+1" active/standby redundancy is a subset of this model. A Note that "1+1" active/standby redundancy is a subset of this model. A
simplex "1+0" model is also supported as a subset, with no ASP simplex "1+0" model is also supported as a subset, with no ASP
redundancy. redundancy.
To avoid a single point of failure, it is recommended that a minimum of To avoid a single point of failure, it is recommended that a minimum of
two ASPs be resident in the list, resident in separate physical two ASPs be in the list, resident in separate hosts and therefore
Application Nodes and therefore available over different SCTP available over different SCTP Associations. For example, in the
Associations. For example, in the network shown in Figure 1, all network shown in Figure 1, all messages to DPC x could be sent to ASP1
messages to DPC x could be sent to ASP1 in AN1 or ASP1 in AN2. The AS in Host1 or ASP1 in Host2. The AS list at SG1 might look like this:
ordered list at SG1 would look like this:
Application Server 1 - Routing Key {DPC=x) Routing Key {DPC=x) "Application Server #1"
ASP1/AN1 - Up, Active ASP1/Host1 State=Up, Active
ASP1/AN2 - Up, Inactive ASP1/Host2 State=Up, Inactive
In this "1+1" redundancy case, ASP1 in AN1 would be sent any incoming In this "1+1" redundancy case, ASP1 in Host1 would be sent any incoming
message with DPC=x. ASP1 in AN2 could be brought to the active state message with DPC=x. ASP1 in Host2 would normally be brought to the
upon failure of, or loss of connectivity to, ASP1/AN1. Both ASPs are active state upon failure of, or loss of connectivity to, ASP1/Host1.
Up, meaning that the related SCTP association and far-end M3UA peer is In this example, both ASPs are Up, meaning that the related SCTP
ready. association and far-end M3UA peer is ready.
The AS List at SG1 might also be set up in loadshare mode:
Routing Key {DPC=x) - Application Server #1
ASP1/Host1 State = Up, Active
ASP1/Host2 State = Up, Active
In this case, both the ASPs would be sent a portion of the traffic.
For example the two ASPs could together form a database, where incoming
queries may be sent to any active ASP.
Care must be exercised by a Network Operator in the selection of the
routing information to be used as the Routing Key for a particular AS.
For example, where Application Servers are defined using ranges of ISUP
CIC values, the Operator is implicitly splitting up control of the
related circuit groups. Some CIC value range assignments may interfere
with ISUP circuit group management procedures. Similarly, within an
AS, if a loadbalancing algorithm were to use CIC values to balance the
load across the ASPs, the span of circuit contol assigned to particular
ASPs must also be weighed against the ISUP circuit group management
procedures.
In the process of fail-over or fail-back, it is recommended that in the In the process of fail-over or fail-back, it is recommended that in the
case of MGCs, stable calls do not fail. It is possible that calls in case of ASPs supporting call processing, stable calls do not fail. It
"transition" may fail, although measures of communication between the is possible that calls in "transition" may fail, although measures of
MGCs involved may mitigate this. For example, the two MGCs may share communication between the ASPs involved can be used to mitigate this.
call state via shared memory, or may use an MGC-MGC protocol to pass For example, the two ASPs may share call state via shared memory, or
call state information. may use an ASP to ASP protocol to pass call state information.
1.3.5 UDP Port 1.3.5 Client/Server Model
A request will be made to IANA to assign a well-known UDP port for The SG takes on the role of server while the ASP is the client. ASPs
M3UA. must initiate the SCTP association to the SG.
The SCTP (and UDP/TCP) Registered User Port Number Assignment for M3UA
is 2905.
1.4 Services Provided by the M3UA Layer 1.4 Services Provided by the M3UA Layer
The M3UA Layer at the ASP provides the equivalent set of primitives at The M3UA Layer at the ASP provides the equivalent set of primitives at
its upper layer to the MTP3-Users as provided by the MTP Level 3 to its its upper layer to the MTP3-Users as provided by the MTP Level 3 to its
local users at an SS7 SEP. In this way, the ISUP and/or SCCP layer at local users at an SS7 SEP. In this way, the ISUP and/or SCCP layer at
an ASP is unaware that the expected MTP3 services are offered remotely an ASP is unaware that the expected MTP3 services are offered remotely
from an MTP3 Layer at an SG and not by a local MTP3 layer. In effect, from an MTP3 Layer at an SG and not by a local MTP3 layer. In effect,
the M3UA extends access to the MTP3 layer services to a remote ASP
the M3UA extends access to the MTP3 layer services to a remote ASP -
the M3UA does not itself provide the MTP3 services so does not the M3UA does not itself provide the MTP3 services so does not
duplicate MTP3 procedures. duplicate MTP3 procedures.
1.4.1 Support for the transport of MTP3-User Messages 1.4.1 Support for the transport of MTP3-User Messages
The M3UA provides the transport of MTP-TRANSFER primitives across SCTP The M3UA provides the transport of MTP-TRANSFER primitives across SCTP
associations between an SG and an ASP. The MTP-TRANSFER primitives are associations between an SG and an ASP. The MTP-TRANSFER primitives are
encoded as ISUP/SCCP messages with attached MTP3 Routing Labels as encoded as MTP3-User messages with attached MTP3 Routing Labels as
described in the message format sections of the SCCP and ISUP described in the message format sections of the SCCP and ISUP
recommendations. In this way, the SCCP and ISUP messages received from recommendations. In this way, the SCCP and ISUP messages received from
the SS7 network are not re-encoded into a different format for the SS7 network are not re-encoded into a different format for
transport to/from the ASP. As well, all the required MTP3 Routing Label transport to/from the ASP. As well, all the required MTP3 Routing Label
information (OPC, DPC, SIO) is available at the ASP as is expected by information (OPC, DPC, SIO) is available at the ASP as is expected by
the ISUP/SCCP layer. For ISUP messages the CIC is available, in its the MTP3-User protocol layer.
native format. The CIC together with the OPC and DPC uniquely identify
all PSTN trunk circuits within a given MTP network instance.
Note that M3UA does not itself impose a 272-octet user information Note that M3UA does not itself impose a 272-octet user information
block limit as specified by the MTP Level 3. Larger information blocks block limit as specified by the MTP Level 3. Larger information blocks
can be accommodated directly by M3UA/SCTP without the need for an upper can be accommodated directly by M3UA/SCTP without the need for an upper
layer segmentation/re-assembly procedure such as specified in recent layer segmentation/re-assembly procedure such as specified in recent
SCCP or ISUP versions. However, in the context of an SG, the maximum 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 272-octet block size must be followed when inter-working to a SS7
network that does not support the transfer of larger information blocks network that does not support the transfer of larger information blocks
to the final destination, as is possible in the Broadband MTP [20]. to the final destination, as is possible in the Broadband MTP [20].
This will avoid ISUP or SCCP fragmentation requirements at the SG. This will avoid ISUP or SCCP fragmentation requirements at the SG.
However, if the SS7 network is provisioned to support the Broadband However, if the SS7 network is provisioned to support the Broadband MTP
MTP, the information block size limit may be increased past 272 octets. to the final SS7 destination, the information block size limit may be
increased past 272 octets.
1.4.2 Native Management Functions 1.4.2 Native Management Functions
The M3UA may provide management of the underlying SCTP transport The M3UA may provide management of the underlying SCTP transport
protocol to ensure that SG-ASP transport is available to the degree protocol to ensure that SG-ASP transport is available to the degree
called for by the MTP3-User signaling applications. called for by the MTP3-User signaling applications.
The M3UA provides the capability to indicate errors associated with The M3UA provides the capability to indicate errors associated with
received M3UA messages and to notify, as appropriate, local management received M3UA messages and to notify, as appropriate, local management
and/or the remote peer M3UA. and/or the remote peer M3UA.
skipping to change at page 13, line 12 skipping to change at page 14, line 51
- Providing an indication to MTP3-Users at an ASP that a remote - Providing an indication to MTP3-Users at an ASP that a remote
destination in the SS7 network is now reachable. destination in the SS7 network is now reachable.
- Providing an indication to MTP3-Users at an ASP that messages to a - Providing an indication to MTP3-Users at an ASP that messages to a
remote MTP3-User peer in the SS7 network are experiencing SS7 remote MTP3-User peer in the SS7 network are experiencing SS7
congestion congestion
- Providing an indication to MTP3-Users at an ASP that a remote MTP3- - Providing an indication to MTP3-Users at an ASP that a remote MTP3-
User peer is unavailable. User peer is unavailable.
The M3UA layer at an ASP may initiate an audit of the availability of The M3UA layer at an ASP may initiate an audit of the availability or
remote SS7 destinations. This information is requested from the M3UA the congested state of remote SS7 destinations. This information is
at the SG. requested from the M3UA at the SG.
1.4.4 Support for the management of SCTP associations between the SG 1.4.4 Support for the management of SCTP associations between the SG
and AN. and ASPs.
The M3UA layer at the SG maintains the availability state of all The M3UA layer at the SG maintains the availability state of all
configured remote ASPs, in order to manage the SCTP Associations and configured remote ASPs, in order to manage the SCTP Associations and
the traffic between the SG and ASPs. As well, the active/inactive the traffic between the SG and ASPs. As well, the active/inactive
state of remote ASPs is also maintained - Active ASPs are those state of remote ASPs is also maintained - Active ASPs are those
currently receiving traffic from the SG. currently receiving traffic from the SG.
The M3UA layer at either the SG or ASP can be instructed by local The M3UA layer at either the SG or ASP can be instructed by local
management to establish an SCTP association to a peer M3UA node. This management to establish an SCTP association to a peer M3UA node. This
can be achieved using the M-SCTP ESTABLISH primitive to request, can be achieved using the M-SCTP ESTABLISH primitive to request,
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The M3UA layer may also need to inform local management of the status The M3UA layer may also need to inform local management of the status
of the underlying SCTP associations using the M-SCTP STATUS request and of the underlying SCTP associations using the M-SCTP STATUS request and
indication primitive. For example, the M3UA may inform local management indication primitive. For example, the M3UA may inform local management
of the reason for the release of an SCTP association, determined either of the reason for the release of an SCTP association, determined either
locally within the M3UA layer or by a primitive from the SCTP. 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 Also the M3UA layer may need to inform the local management of the
change in availability status of an ASP. This can be achieved using change in availability status of an ASP. This can be achieved using
the M-ASP STATUS primitive to change and indicate the status of an ASP. the M-ASP STATUS primitive to change and indicate the status of an ASP.
1.5 Internal Functions Provided in the M3UA Layer 1.5 Internal Functions in the M3UA
1.5.1 Address Translation and Mapping at the SG M3UA 1.5.1 Address Translation and Mapping at the SG M3UA
In order to direct messages received from the MTP3 network to the In order to direct messages received from the SS7 MTP3 network to the
desired IP destination, the SG M3UA must perform address translation desired IP destination, the SG M3UA must perform address translation
and mapping functions using information from the received ISUP/SCCP and mapping functions using information from the received MTP3-User
message. message.
To support this mapping, the SG must maintain a network address To support this mapping, the SG must maintain a network address
translation table, mapping incoming SS7 information to an ordered list translation table, mapping incoming SS7 message information to an
of an Application Server Processes. Note that in certain failure and Application Server serving a particular application and range of
transition cases it is possible that there may not be an active ASP traffic. This is accomplished by comparing a set of the information in
available. an incoming SS7 message to provisioned SG Routing Keys to determine an
Application Server that serves a particular range of traffic.
This table is assumed to be dynamic, taking into account the Possible SS7 address/routing information that may comprise a Routing
availability status of the individual ASPs in the list, configuration Key entry includes, for example, the OPC, DPC, SIO, ISUP CIC range or
changes, and possible fail-over mechanisms. The M3UA protocol includes SCCP Subsystem Number. The particular information used in an SG M3UA
messages to convey the availability status of the individual ASPs as Routing Key is application and network dependent.
input to a fail-over mechanism.
Possible SS7 address/routing information that may comprise a routing An Application Server contains a list of one or more ASPs which are
key entry includes, for example, the OPC, DPC, SIO, ISUP CIC range or capable of processing the traffic. This list is assumed to be dynamic,
SCCP Called Party Address. The particular information used in an SG taking into account the availability status of the individual ASPs in
M3UA is implementation dependent.
the list, configuration changes, and possible fail-over mechanisms.
The M3UA protocol includes messages to convey the availability status
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 that there may not be an active ASP available. Both
loadsharing and backup scenarios are supported.
Where there is no Routing Key match for an incoming SS7 message, a
default treatment must be specified. Possible solutions are to provide
a "Default" Application Server at the SG that will direct all
unallocated traffic to a (set of) "Default" ASP(s), or to drop the
messages and provide a notification to management.
1.5.2 SG Redundancy 1.5.2 SG Redundancy
It is possible that the ASP could route signaling messages destined to It is possible that the ASP could route signaling messages destined to
the SS7 network through more than one SG. A primary/back-up case is the SS7 network through more than one SG. A primary/back-up case is
possible where the unavailability of the ASP Path to a primary SG, or possible where the unavailability of the SCTP assocation to a primary
the unavailability of the SS7 destination node from the primary SG, SG, or the unavailability of the SS7 destination node from the primary
could be used to reroute to a next-preferred SG. Also, a load-sharing SG, could be used to reroute affected traffic to a next-preferred SG.
case is possible where the signaling messages are load-shared across Also, a load-sharing case is possible where the signaling messages are
two (or more) SGs. load-shared across two (or more) SGs.
1.5.3 SCTP Stream Mapping. The M3UA at both the SG and ASP also >From the perspective of an ASP, it is assumed that a particular SG is
supports the assignment of signaling traffic into streams within an capable of handling traffic to an SS7 destination if an SCTP
SCTP association. Traffic that requires sequencing must be assigned to association to the SG is available, the SG has received an indication
the same stream. To accomplish this, ISUP/SCCP traffic may be assigned from the ASP that it is currently actively handling traffic, and the SG
to individual streams based on the SLS value in the MTP3 Routing Label has not indicated that the SS7 destination is unavailable. Where an
or the ISUP CIC assignment, subject of course to the maximum number of ASP is configured to use two or more SGs for directing traffic to the
streams supported by the underlying SCTP association. SS7 network, the ASP must maintain knowledge of the current capability
of the SG to handle traffic to destinations of interest, for the
purpose of efficiently supporting the redirection/loadsharing of
traffic. The ASP may also use information received from the SGs of
congestion to concerned destinations.
1.5.3 SCTP Stream Mapping.
The M3UA at both the SG and ASP also supports the assignment of
signaling 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 the SLS value in the MTP3 Routing Label or the ISUP
CIC assignment, subject of course to the maximum number of streams
supported by the underlying SCTP association.
1.5.4 Congestion Control. 1.5.4 Congestion Control.
The M3UA Layer is informed of local and IP network congestion by means The M3UA Layer is informed of local and IP network congestion by means
of an implementation-dependent function (e.g., an implementation- of an implementation-dependent function (e.g., an implementation-
dependent indication from the SCTP of IP network congestion). When an dependent indication from the SCTP of IP network congestion). When an
SG determines that the transport of SS7 messages to an MTP3 Management SG determines that the transport of SS7 messages to an Signalling Point
Cluster is encountering congestion, the SG may optionally trigger SS7 Management Cluster (SPMC) is encountering congestion, the SG may
MTP3 Transfer Controlled management messages to originating SS7 nodes. optionally trigger SS7 MTP3 Transfer Controlled management messages to
The triggering of SS7 MTP3 Management messages from an SG is an originating SS7 nodes. The triggering of SS7 MTP3 Management messages
implementation-dependent function. At an ASP, congestion is indicated from an SG is an implementation-dependent function. At an ASP,
to local MTP3-Users by means of an MTP-Status primitive indicating congestion is indicated to local MTP3-Users by means of an MTP-Status
congestion, to invoke appropriate upper layer responses, as per current primitive indicating congestion, to invoke appropriate upper layer
MTP3 procedures. responses, as per current MTP3 procedures.
1.5.5 Seamless Network Management Inter-working. 1.5.5 Seamless Network Management Inter-working.
The M3UA at an SG must maintain knowledge of SS7 node and MTP3 The M3UA at an SG must maintain knowledge of SS7 node and Signalling
Management Cluster status in their respective domains in order to Point Management Cluster (SPMC) status in their respective domains in
perform as seamless as possible inter-working of the two domains. For order to perform as seamless as possible inter-working of the two
example, SG M3UA knowledge of the availability and/or congestion status domains. For example, SG M3UA knowledge of the availability and/or
of MTP3 Management Cluster and SS7 nodes must be maintained and congestion status of SPMC and SS7 nodes must be maintained and
disseminated in the respective networks so that end-to-end operation is disseminated in the respective networks so that end-to-end operation is
transparent to the communicating SCN protocol peers at the SS7 node and transparent to the communicating SCN protocol peers at the SS7 node and
ASP. ASP.
When an SG M3UA determines that the transport of SS7 messages to an When an SG M3UA determines that the transport of SS7 messages to an
MTP3 Management Cluster is encountering congestion, the SG may SPMC is encountering congestion, the SG may optionally inform the MTP3
optionally inform the MTP3 route management function (by an route management function (by an implementation-dependent mechanism).
implementation-dependent mechanism). This information is used by the This information is used by the MTP3 to mark the route to the affected
MTP3 to mark the route to the affected destination as congested and to destination as congested and to trigger MTP Transfer Controlled (TFC)
trigger MTP Transfer Controlled (TFC) messages to any SS7 SEPs messages to any SS7 SEPs generating traffic to the congested DPC, as
generating traffic to the congested DPC, as per current MTP3 per current MTP3 procedures.
procedures.
When an SG M3UA determines that the transport of SS7 messages to all When an SG M3UA determines that the transport of SS7 messages to all
ASPs in a particular MTP3 Management Cluster is interrupted, the SG ASPs in a particular SPMC is interrupted, the SG M3UA may similarly
M3UA may similarly optionally inform the MTP3 route management optionally inform the MTP3 route management function. This information
function. This information is used by the MTP3 to mark the route to the is used by the MTP3 to mark the route to the affected destination as
affected destination as unavailable and to trigger MTP Transfer unavailable and to trigger MTP Transfer Prohibited (TFP) messages to
Prohibited (TFP) messages to the adjacent SS7 nodes which are the adjacent SS7 nodes which are generating traffic to the unavailable
generating traffic to the unavailable DPC as per current MTP DPC as per current MTP procedures. If the SG is considered part of the
procedures. SPMC, MTP TFP messages must not be triggered into the SS7 network, as
SS7 procedures do not support the sending of TFPs by an SS7 node to
indicate its own unavailability.
When an SG M3UA determines that the transport of SS7 messages to an ASP When an SG M3UA determines that the transport of SS7 messages to an ASP
in a particular MTP3 Management Cluster can be resumed, the SG M3UA may in a particular SPMC can be resumed, the SG M3UA may similarly
similarly optionally inform the MTP3 route management function. This optionally inform the MTP3 route management function. This information
information is used by the MTP3 to mark the route to the affected is used by the MTP3 to mark the route to the affected destination as
destination as available and to trigger MTP Transfer Allowed (TFA) now available and to trigger MTP Transfer Allowed (TFA) messages to the
messages to the adjacent SS7 nodes as per current MTP3 procedures. adjacent SS7 nodes as per current MTP3 procedures.
Note: In some SS7 network architectures, the sending of TFP and TFA Note: In some SS7 network architectures, the sending of TFP and TFA
messages from the SG into the SS7 network should be suppressed. For messages from the SG into the SS7 network should be suppressed. For
example, in the case where an SG seen by the adjacent SS7 node as an example, in the case where an SG seen by the adjacent SS7 nodes as an
SEP (i.e., in ANSI MTP terms they are connected via A-links or F- SEP (i.e., in ANSI MTP terms the SG is connected via A-links or F-
links), TFP or TFA messages would not normally be expected by the links), TFP or TFA messages would not normally be expected by the
adjacent SS7 node. adjacent SS7 node.
1.5.6 Management Inhibit/Uninhibit 1.5.6 Management Inhibit/Uninhibit
Local Management at an ASP or SG may wish to stop traffic across an Local Management at an ASP or SG may wish to stop traffic across an
SCTP association in order to temporarily remove the association from SCTP association in order to temporarily remove the association from
service or to perform testing and maintenance activity. The function service or to perform testing and maintenance activity. The function
could optionally be used to control the start of traffic on to a newly- could optionally be used to control the start of traffic on to a newly-
available SCTP association. available SCTP association.
skipping to change at page 17, line 27 skipping to change at page 19, line 51
Destination Unavailable (DUNA) 0201 Destination Unavailable (DUNA) 0201
Destination Available (DAVA) 0202 Destination Available (DAVA) 0202
Destination State Audit (DAUD) 0203 Destination State Audit (DAUD) 0203
SS7 Network Congestion State (SCON) 0204 SS7 Network Congestion State (SCON) 0204
Destination User Part Unavailable (DUPU) 0205 Destination User Part Unavailable (DUPU) 0205
Application Server Process Maintenance (ASPM) messages Application Server Process Maintenance (ASPM) messages
ASP Up 0301 ASP Up 0301
ASP Down 0302 ASP Down 0302
Heartbeat 0303
ASP Active 0401 ASP Active 0401
ASP Inactive 0402 ASP Inactive 0402
Management (MGMT) Messages Management (MGMT) Messages
Error 0000 Error 0000
Notify 0001
2.1.3 Message Length 2.1.3 Message Length
The Message Length defines the length of the message in octets, not The Message Length defines the length of the message in octets, not
including the header. including the header.
2.2 ISUP/SCCP Transfer Messages 2.2 Transfer Messages
The following section describes the ISUP/SCCP Transfer messages and The following section describes the Transfer messages and parameter
parameter contents. The general message format includes a Common contents. The general message format includes a Common Message Header
Message Header together with a list of zero or more parameters as together with a list of zero or more parameters as defined by the
defined by the Message Type. All Message Types can have attached Message Type. All Message Types can have attached parameters.
parameters.
2.2.1 Data Message 2.2.1 Data Message
The Data message contains SS7 MTP3-User protocol data, which is an MTP- The Data message contains the SS7 MTP3-User protocol data, which is an
TRANSFER primitive, including the complete MTP3 Routing Label. The Data MTP-TRANSFER primitive, including the complete MTP3 Routing Label. The
message contains the following parameters: Data message contains the following parameters:
PROTOCOL IDENTIFIER (Optional)
NETWORK APPEARANCE (Optional) NETWORK APPEARANCE (Optional)
PROTOCOL DATA PROTOCOL DATA
The format for the Data Message parameters is as follows: The format for the Data Message parameters is as follows:
0 1 2 3 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 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 (0xx) | Length | | Tag (0x1) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol Identifier* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Appearance* | | Network Appearance* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Tag (0x3) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol Data | | Protocol Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Protocol Identifier parameter identifies explicitly the MTP3-User The optional Network Appearance parameter identifies the SS7 network
Part being transported, where the SCN protocol carried is context for the message, for the purposes of logically separating the
not known implicitly in the context of a particular SCTP signaling traffic between the SG and the Application Server Process
association/stream or Network Appearance/SIO. The Protocol Id defines over a common SCTP Association. An example is where an SG is logically
the protocol type, variant, and version, and thereby specifies the partitioned to appear as an element in four different national SS7
components and encoding of the Protocol Data parameter. Protocol Ids networks.
will be maintained by IANA outside of this document and may be
registered on an "as needed" basis. The Protocol Id is not required in
Data messages if the Protocol Id information is pre-configured or
identified at Association or Path establishment.
Ed Note: The Protocol Id format is an OID as defined in .....
The Network Appearance identifies the SS7 network context for the In a Data message, the Network Appearance defines the SS7 Point Codes
message, for the purposes of logically separating the signaling traffic used, the SS7 Network Indicator value and MTP3/MTP3-User protocol
between the SG and the Application Server Processes over common SCTP type/variant/version used within the SS7 network partition. Where an
Associations. An example is where an SG is logically partitioned to SG operates in the context of a single SS7 network, or individual SCTP
appear as an element in four different national networks. A Network associations are dedicated to each SS7 network context, or the Network
Appearance implicitly defines the SS7 Destination Point Code, Network Indicator in the SIO of the MTP-Transfer primitive is sufficient, the
Indicator and MTP3 protocol type/variant/version used within each Network Appearance parameter is not required.
network.
The format is an ASCII string, the values of which are assigned The format is an integer, the values of which are assigned according to
network operator policy. The values used are of local significance
only, coordinated between the SG and ASP.
according to network operator policy. The Network Appearance string Where the optional Network Appearance parameter is present, it must be
should be padded to 32-bit boundaries. the first parameter in the message as it defines the format of the
Protocol Data field.
The Protocol Data field contains the MTP3-User application message, The Protocol Data field contains the MTP3-User application message,
which is in effect an MTP-TRANSFER primitive. As defined for a which is in effect an MTP-TRANSFER primitive. As defined for a
specific value of the Protocol Identifier, this will include the MTP- specific value of the Protocol Identifier, this will include the MTP-
User Data and includes the MTP Routing Label (SS7 OPC, DPC, SLS), and User Data and includes the MTP Routing Label (SS7 OPC, DPC, SLS), and
the SIO (Service Indicator, Network Indicator & optional Message the SIO (Service Indicator, Network Indicator & optional Message
Priority codes). In the case of ISUP messages, the Circuit Priority codes). Note: in the case of ISUP messages, the Circuit
Identification Code is also included. Identification Code is also included.
2.3.2 SS7 Signaling Network Management (SSNM) Messages 2.3 SS7 Signaling Network Management (SSNM) Messages
2.3.2.1 Destination Unavailable (DUNA)
2.3.1 Destination Unavailable (DUNA)
The DUNA message is sent from the SG to all concerned ASPs to indicate The DUNA message is sent from the SG to all concerned ASPs to indicate
that the SG has determined that an SS7 destination is unreachable. The that the SG has determined that one or more SS7 destinations are
MTP3-User at the ASP is expected to stop traffic to the affected unreachable. The MTP3-User at the ASP is expected to stop traffic to
destination through the SG initiating the DUNA. the affected destination through the SG initiating the DUNA as per the
defined MTP3-User procedures.
The DUNA message contains the following parameters: The DUNA message contains the following parameters:
Protocol Identifier (Optional)
Network Appearance (Optional) Network Appearance (Optional)
Affected Destination Point Code Affected Destination
Info String (Optional) Info String (Optional)
The format for DUNA Message parameters is as follows: The format for DUNA Message parameters is as follows:
0 1 2 3 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 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 (0xx) | Length | | Tag (0x1) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Appearance* |
| (MTP) Protocol Identifier* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Tag (0x5) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Spare | Affected DPC 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Appearance* | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Spare | Affected DPC n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Spare | Affected DPC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Tag (0x4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INFO String* | | INFO String* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Protocol Identifier parameter is defined similarly to Section 2.2.1 The optional Network Appearance parameter identifies the SS7 network
but in this case defines the MTP3 version/variant. In this context it context for the message, for the purposes of logically separating the
defines the format of the Affected DPC parameter. By identifying the signaling traffic between the SG and the Application Server Process
MTP variant and version, the point code length (e.g., 14-, 16-, or 24- over a common SCTP Association. An example is where an SG is logically
bit) and sub-field definitions (e.g., ANSI network/cluster/member, ITU- partitioned to appear as an element in four different national SS7
international zone/region/signal_point, many national field variants, networks.
...) can be determined.
The Network Appearance is defined as in Section 2.2.1 In an SSNM message, the Network Appearance parameter defines the format
of the Affected DPC(s) in the Affected Destination parameter. The DPC
point code length (e.g., 14-, 16-, or 24-bit) and sub-field definitions
(e.g., ANSI network/cluster/member, ITU-international
zone/region/signal_point, many national field variants, ...) are fixed
within a particular Network Appearance. 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 and the format of the Affected DPC(s) is understood
implicitly.
The INFO String parameter can carry any meaningful 8-BIT ASCII The format of the Network Appearance parameter is an integer, the
values of which are assigned according to network operator policy. The
values used are of local significance only, coordinated between the SG
and ASP.
Where the optional Network Appearance parameter is present, it must be
the first parameter in the message as it defines the format of the
Affected DPCs in the Affected Destination parameter.
The Affected Destination parameter contains one or optionally more
Affected Destination Point Codes, each a three-octet parameter to allow
14-, 16- and 24-bit binary formatted SS7 Point Codes. Where the
Affected Point Code is less than 24-bits, it is padded on the left to
the 24-bit boundary.
It is optional to send an Affected Destination parameter with more than
one Affected DPC but it is mandatory to receive it. Also all the
Affected DPCs included must be part of the same Network Appearance.
Including multiple Affected DPCs may be useful when, for example, ANSI
Cluster Route Sets are used at the SG, or a linkset event at the SG is
simultaneously affecting the status of many destinations.
The optional INFO String parameter can carry any meaningful 8-BIT ASCII
character string along with the message. Length of the INFO String character string along with the message. Length of the INFO String
parameter is from 0 to 255 characters. No procedures are presently 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 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 identify in text form the location reflected by the Affected DPC for
debugging purposes. debugging purposes.
The Affected DPC is provisionally a three-octet parameter to allow 14-, 2.3.2 Destination Available (DAVA)
16- and 24-bit binary formatted SS7 Point Codes.
2.3.2.2 Destination Available (DAVA)
The DAVA message is sent from the SG to all concerned ASPs to indicate The DAVA message is sent from the SG to all concerned ASPs to indicate
that the SG has determined that an SS7 destination is now reachable. that the SG has determined that one or more SS7 destinations are now
The ASP MTP3-User protocol is expected to resume traffic to the reachable. The ASP MTP3-User protocol is expected to resume traffic to
affected destination through the SG initiating the DUNA. the affected destination through the SG initiating the DUNA.
The DAVA message contains the following parameters: The DAVA message contains the following parameters:
Protocol Identifier (Optional)
Network Appearance (Optional) Network Appearance (Optional)
Affected Destination Point Code Affected Destination
Info String (Optional) Info String (Optional)
The format and description of DAVA Message parameters is the same as The format and description of DAVA Message parameters is the same as
for the DUNA message (See Section 2.3.2.1.) for the DUNA message (See Section 2.3.2.1.)
2.3.2.3 Destination State Audit (DAUD) 2.3.3 Destination State Audit (DAUD)
The DAUD message can be sent from the ASP to the SG to query the The DAUD message can be sent from the ASP to the SG to audit the
availability state of the SS7 routes to an affected destination. A availability/congestion state of SS7 routes to one or more affected
DAUD may be sent periodically after the ASP has received a DUNA, until destinations. See Section 3.4.3 for the audit procedures.
a DAVA is received. The DAUD can also be sent when an ASP recovers
from isolation from the SG.
The DAUD message contains the following parameters: The DAUD message contains the following parameters:
Protocol Identifier (Optional)
Network Appearance (Optional) Network Appearance (Optional)
Affected Destination Point Code Affected Destination
Info String (Optional) Info String (Optional)
The format and description of DAUD Message parameters is the same as The format and description of DAUD Message parameters is the same as
for the DUNA message (See Section 2.3.2.1.) for the DUNA message (See Section 2.3.2.1.)
2.3.2.4 SS7 Network Congestion (SCON) Multiple Affected Destination Point Codes parameters may optionally be
included in a DAUD message. However all the Affected Destination Point
Codes must be part of the same Network Appearance.
2.3.4 SS7 Network Congestion (SCON)
The SCON message can be sent from the SG to all concerned ASPs to The SCON message can be sent from the SG to all concerned ASPs to
indicate that the congestion level in the SS7 network to a specified indicate that the congestion level in the SS7 network to one or more
destination has changed. destinations has changed.
The SCON message contains the following parameters: The SCON message contains the following parameters:
Protocol Identifier (Optional)
Network Appearance (Optional) Network Appearance (Optional)
Affected Destination Point Code Affected Destination
Congestion Level
Info String (Optional) Info String (Optional)
Congestion Level (Optional)
The format for SCON Message parameters is as follows: The format for SCON Message parameters is as follows:
0 1 2 3 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 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 (0xx) | Length | | Tag (0x1) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Appearance* |
| Protocol Identifier* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Tag (0x5) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cong. Level 1 | Affected DPC 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Appearance | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Cong. Level n | Affected DPC n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cong. Level | Affected DPC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Tag (0x4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INFO String* | | INFO String* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format and description of the Protocol Identifier, Network The format and description of the Network Appearance, Affected
Appearance, Affected DPC and Info String parameters is the same as for Destination and Info String parameters is the same as for the DUNA
the DUNA message (See Section 2.3.2.1.) message (See Section 2.3.2.1.)
The valid values for the optional Congestion Level parameter are shown The valid values for the optional Congestion Level parameter are shown
in the following table. in the following table.
Value Description Value Description
00 No Congestion or Undefined 00 No Congestion or Undefined
01 Congestion Level 1 01 Congestion Level 1
02 Congestion Level 2 02 Congestion Level 2
03 Congestion Level 3 03 Congestion Level 3
The congestion levels are as defined in the national congestion method The congestion levels are as defined in the national congestion method
in the ITU MTP recommendation [14] or in the ANSI MTP standard [15]. in the ITU MTP recommendation [14] or in the ANSI MTP standard [15].
For MTP versions/variants without congestion levels, for example the For MTP congestion methods that do not employ congestion levels (e.g.,
ITU international method, the parameter is always Undefined. the ITU international method, the parameter is always "Undefined".
2.3.2.5 Destination User Part Unavailable (DUPU) 2.3.5 Destination User Part Unavailable (DUPU)
The DUPU message is used by a SG to inform an ASP that a remote peer The DUPU message is used by an SG to inform an ASP that a remote peer
MTP3-User User Part (e.g., ISUP or SCCP) at an SS7 node is unavailable. MTP3-User User Part (e.g., ISUP or SCCP) at an SS7 node is unavailable.
The DUPU message contains the following parameters: The DUPU message contains the following parameters:
Protocol Identifier (Optional)
Network Appearance (Optional) Network Appearance (Optional)
Affected Destination Point Code Affected Destination
Unavailability Cause
MTP3-User Identity
Info String (Optional) Info String (Optional)
Reason
The format for DUPU Message parameters is as follows: The format for DUPU Message parameters is as follows:
0 1 2 3 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 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 (0xx) | Length | | Tag (0x1) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol Identifier* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Appearance* | | Network Appearance* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Tag (0x5) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason | Affected DPC | | Cause | User | Affected Destination |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0xx) | Length | | Tag (0x4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INFO String* | | INFO String* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format and description of the Protocol Identifier, Network The format and description of the Network Appearance, Affected
Appearance, Affected DPC and Info String parameters is the same as for Destination and Info String parameters is the same as for the DUNA
the DUNA message (See Section 2.3.2.1.) message (See Section 2.3.2.1.) One exception is that the Affected
Desination parameter in the DUPU message can only contain one Affected
DPC.
The valid values for Reason are shown in the following table. 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 context,
additional values may be used the specification of the relevant MTP3
protocol variant/version is definitive.
Define Value Description Value Description
UPU-Unknown 01 MTP User Part Unavailable, No Reason Given 00 Unknown
UPU-Unequipped 02 MTP User Part Unavailable, Unequipped 01 Unequipped Remote User
UPU-Inaccessible 03 MTP User Part Unavailable, Inaccessible 02 Inaccessible Remote User
2.3.3 Application Server Process Maintenance (ASPM) Messages The MTP3-User Identity describes the specific MTP3-User that is
unavailable (e.g., ISUP, SCCP, ...). 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 used in the network context, additional
2.3.3.1 ASP Up (ASPUP) values may be used the specification of the relevant MTP3 protocol
variant/version is definitive.
Value Description
00 - 02 Reserved
03 SCCP
04 TUP
05 ISUP
06 08 Reserved
09 Broadband ISUP
10 Satellite ISUP
2.4 Application Server Process Maintenance (ASPM) Messages
2.4.1 ASP Up (ASPUP)
The ASP UP (ASPUP) message is used to indicate to a remote M3UA peer The ASP UP (ASPUP) message is used to indicate to a remote M3UA peer
that the Adaptation layer is ready to receive traffic or maintenance that the Adaptation layer is ready to receive traffic or maintenance
messages. messages.
The ASPUP message contains the following parameters: The ASPUP message contains the following parameters:
Adaptation Layer Identifer (optional) Adaptation Layer Identifer (optional)
Protocol Identifier (optional) Protocol Identifier (optional)
INFO String (optional) INFO String (optional)
skipping to change at page 24, line 16 skipping to change at page 27, line 42
0 1 2 3 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 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 (0x2) | Length | | Tag (0x2) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adaptation Layer Identifier* | | Adaptation Layer Identifier* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x3) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol Identifier* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x4) | Length | | Tag (0x4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INFO String* | | INFO String* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format and description of the optional Protocol Identifier and Info The format and description of the optional Info String parameters is
String parameters is the same as for the DUNA message (See Section the same as for the DUNA message (See Section 2.3.2.1.)
2.3.2.1.)
The optional Adaptation Layer Identifier (ALI) is a string that The optional Adaptation Layer Identifier (ALI) is a string that
identifies the adaptation layer. This string must be set to "M3UA" identifies the adaptation layer. This string must be set to "M3UA"
which results in a length of 4. The ALI would normally only be used in which results in a length of 4. The ALI would normally only be used in
the initial ASP Up message across a new SCTP association to ensure both the initial ASP Up message across a new SCTP association to ensure both
peers are assuming the same adaptation layer protocol. peers are assuming the same adaptation layer protocol.
Note: Strings are padded to 32-bit boundaries. The length field Note: Strings are padded to 32-bit boundaries. The length field
indicates the end of the string. indicates the end of the string.
2.3.3.2 ASP Down (ASPDN) 2.4.2 ASP Down (ASPDN)
The ASP Down (ASPDN) message is used to indicate to a remote M3UA peer The ASP Down (ASPDN) message is used to indicate to a remote M3UA peer
that the adaptation layer is not ready to receive traffic or that the adaptation layer is not ready to receive traffic or
maintenance messages. maintenance messages.
The ASPDN message contains the following parameters: The ASPDN message contains the following parameters:
Reason Reason
INFO String (Optional) INFO String (Optional)
skipping to change at page 25, line 28 skipping to change at page 28, line 47
same as for the DUNA message (See Section 2.3.2.1.) same as for the DUNA message (See Section 2.3.2.1.)
The Reason parameter indicates the reason that the remote M3UA The Reason parameter indicates the reason that the remote M3UA
adaptation layer is unavailable. The valid values for Reason are shown adaptation layer is unavailable. The valid values for Reason are shown
in the following table. in the following table.
Value Description Value Description
0x1 Processor Outage 0x1 Processor Outage
0x2 Management Inhibit 0x2 Management Inhibit
2.3.3.3 ASP Active (ASPAC) 2.4.3 ASP Active (ASPAC)
The ASPAC message is sent by an ASP to indicate to an SG that it is The ASPAC message is sent by an ASP to indicate to an SG that it is
Active and ready to be used. Active and ready to be used.
The ASPAC message contains the following parameters: The ASPAC message contains the following parameters:
Type
Routing Context (Optional) Routing Context (Optional)
INFO String (Optional) INFO String (Optional)
The format for the ASPAC message is as follows: The format for the ASPAC message is as follows:
0 1 2 3 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 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 (0xx) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | | Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x6) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Routing Context* | | Routing Context* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x4) | Length | | Tag (0x4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INFO String* | | INFO String* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Type parameter identifies the ASPAC as an Over-ride or Load-share The Type parameter identifies the traffic mode of operation of the ASP
Active message. The valid values for Type are shown in the following within an AS. The valid values for Type are shown in the following
table. table.
Value Description Value Description
0x1 Over-ride 0x1 Over-ride
0x2 Load-share 0x2 Load-share
0x3 New traffic
Within a particular Routing Context, only one Type can be used. An SG Within a particular Routing Context, only one Type can be used. The
that receives an ASPAC with an incorrect type for a particular Routing Over-ride value indicates that the ASP is operating in Over-ride mode,
Context will respond with an Error Message. where 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 loadshare mode, the ASP will share in the traffic
distribution with any other currently active ASPs. In New Traffic mode
the ASP wishes to take on traffic in the AS but does not expect to
receive messages related to calls/transactions that are pending
completion in another ASP.
An SG that receives an ASPAC with an incorrect type for a particular
Routing Context will respond with an Error Message.
The optional Routing Context parameter contains (a list of) integers The optional Routing Context parameter contains (a list of) integers
indexing the Application Server traffic that the sending ASP is indexing the Application Server traffic that the sending ASP is
conigured to receive. There is one-to-one relationship between an configured/registered to receive. There is one-to-one relationship
index entry and an AS Name. Because an AS can only appear in one between an index entry and an SG Routing Key or AS Name. Because an AS
Network Appearance, the Network Appearance parameter is not required in can only appear in one Network Appearance, the Network Appearance
the ASPAC message parameter is not required in the ASPAC message
An Application Server Process may be configured to process traffic for An Application Server Process may be configured to process traffic for
more than one logical Application Server. From the perspective of an more than one logical Application Server. From the perspective of an
ASP, a Routing Context defines a range of signaling traffic that the ASP, a Routing Context defines a range of signaling traffic that the
ASP is currently configured to receive from the SG. For example, an ASP is currently configured to receive from the SG. For example, an
ASP could be configured to support call processing for multiple ranges ASP could be configured to support call processing for multiple ranges
of PSTN trunks and therefore receive related signaling traffic, of PSTN trunks and therefore receive related signaling traffic,
identified by separate SS7 DPC/OPC/CIC_ranges. identified by separate SS7 DPC/OPC/CIC_ranges.
The format and description of the optional Info String parameter is the The format and description of the optional Info String parameter is the
same as for the DUNA message (See Section 2.3.2.1.) same as for the DUNA message (See Section 2.3.2.1.)
2.3.3.4 ASP Inactive (ASPIA) 2.4.4 ASP Inactive (ASPIA)
The ASPIA message is sent by an ASP to indicate to an SG that it is no The ASPIA message is sent by an ASP to indicate to an SG that it is no
longer an active ASP to be used from within a list of ASPs. The SG longer an active ASP to be used from within a list of ASPs. The SG
will respond with an ASPIA message and either discard incoming messages will respond with an ASPIA message and either discard incoming messages
or buffer for a timed period and then discard. or buffer for a timed period and then discard.
The contains the following parameters: The ASPIA message contains the following parameters:
Type
Routing Context (Optional) Routing Context (Optional)
INFO String (Optional) INFO String (Optional)
The format for the ASPIA message parameters is as follows: The format for the ASPIA message parameters is as follows:
0 1 2 3 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 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 (0xx) | Length | | Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x6) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Routing Context | | Routing Context* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x4) | Length | | Tag (0x4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INFO String* | | INFO String* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The 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.
Value Description
0x1 Over-ride
0x2 Load-share
0x3 Graceful Withdrawal
The format and description of the optional Routing Context and Info The format and description of the optional Routing Context and Info
String parameters is the same as for the ASPAC message (See Section String parameters is the same as for the ASPAC message (See Section
2.3.3.3.) 2.3.3.3.)
2.3.4 Management Messages 2.4.5 Heartbeat (BEAT)
2.3.4.1 Error (ERR) 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 other than the SCTP, which has its own
heartbeat.
The BEAT message contains no parameters.
2.5 Management Messages
2.5.1 Error (ERR)
The ERR message is sent when an invalid value is found in an incoming The ERR message is sent when an invalid value is found in an incoming
message. message.
The ERR message contains the following parameters: The ERR message contains the following parameters:
Error Code Error Code
Diagnostic Information (optional)
The format for the ERR message is as follows: The format for the ERR message is as follows:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code | | Error Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x7) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Error Code can be one of the following values: | Diagnostic Information* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Error Code parameter indicates the reason for the Error Message.
The Error parameter value can be one of the following values:
Invalid Version 0x1 Invalid Version 0x1
Invalid Network Appearance 0x2 Invalid Network Appearance 0x2
Invalid SCN Version 0x3 Invalid Adaptation Layer Identifier 0x3
Invalid Adaptation Layer Identifier 0x4 Invalid Message Type 0x4
Invalid Stream Identifier 0x5 Invalid Traffic Handling Mode 0x5
Invalid Message Type 0x6
The optional Diagnostic information can be any information germain to
the error condition, to assist in identification of the error
condition. In the case of an Invalid Version Error Code the Diagnostic
information includes the supported Version parameter. In the other
cases, the Diagnostic information may be the first 40 bytes of the
offending message.
Error messages are not generated in response to other Error messages.
2.5.2 Notify (NTFY)
The Notify message used to provide an autonomous indication of M3UA
events to an M3UA peer.
The NTFY message contains the following parameters:
Status Type
Status Identification
Routing Context (Optional)
INFO String (Optional)
The format for the 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status Type | Status Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x6) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Routing Context* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (0x4) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INFO String* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Status Type parameter identifies the type of the Notify message.
Following are the valid Status Type values:
Value Description
0x1 Application Server state change (AS_State_Change)
0x2 Application Server Process state change (ASP_State_Change)
0x3 Other
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:
Value Description
0x1 Application Server Down (AS_Down)
0x2 Application Server Up (AS_Up)
0x3 Application Server Active (AS_Active)
0x4 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 ASP_State_Change, the Status Information values
are:
Value Description
0x1 Application Server Process (ASP) Down
0x2 Application Server Process (ASP) Up
0x3 Application Server Process (ASP) Active
0x4 Application Server Process (ASP) Active_Old
0x5 Application Server Process (ASP) Active_New
These notifications are sent from an SG to an ASP upon a change in
status of a particular Application Server process within the ASP list
of a particular Application Server. The value reflects the new state
of the Application Server Process.
If the Status Type is Other, then the following Status Information
values are defined:
Value Description
0x1 Insufficient ASP resources active in AS
This notification is not based on the SG reporting the state change of
an ASP or AS. For the value defined the SG is indicating to an ASP(s)
in the AS that another ASP is required in order to handle the load of
the AS.
The format and description of the optional Routing Context and Info
String parameters is the same as for the ASPAC message (See Section
2.3.3.3.)
3.0 Procedures 3.0 Procedures
The M3UA layer needs to respond to various local primitives it receives The M3UA layer needs to respond to various local primitives it receives
from other layers as well as the messages that it receives from the from other layers as well as the messages that it receives from the
peer M3UA layers. This section describes the M3UA procedures in peer M3UA layers. This section describes the M3UA procedures in
response to these events. response to these events.
3.1 Procedures to support the services of the M3UA layer 3.1 Procedures to support the services of the M3UA layer
skipping to change at page 28, line 25 skipping to change at page 34, line 27
3.1.1 Receipt of Local primitives 3.1.1 Receipt of Local primitives
On receiving an MTP-Transfer primitive from an upper layer, or the On receiving an MTP-Transfer primitive from an upper layer, or the
nodal inter-working function at an SG, the M3UA layer will send a nodal inter-working function at an SG, the M3UA layer will send a
corresponding Data message (see Section 2) to its M3UA peer. The M3UA corresponding Data message (see Section 2) to its M3UA peer. The M3UA
layer must fill in various fields of the common and specific headers layer must fill in various fields of the common and specific headers
correctly. correctly.
At an SG, the M3UA address translation and mapping function determines At an SG, the M3UA address translation and mapping function determines
the logical Application Server based on the information in the incoming the Application Server (AS) based on the information in the incoming
message. From an ordered list of ASPs within the AS table, the Active message. From an ordered list of ASPs within the AS table, an Active
ASP is selected and the Data message is constructed and issued on the 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., 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 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 active ASPs from the list is selected. The selection algorithm is
implementation dependent but could be based on, for example, the SLS or implementation dependent but could be roud-robin or based on, for
ISUP CIC. example, the SLS or ISUP CIC. The appropriate selection algorithm must
be chosen carefully as it is dependent on application assumptions and
understanding of the degree of state coordination between the active
ASPs in the AS.
In addition, the message needs to be sent on the appropriate SCTP In addition, the message needs to be sent on the appropriate SCTP
stream, taking care to conserve the message sequencing needs of the stream, again taking care to meet the message sequencing needs of the
signaling application. signaling application.
Ed Note: Further description of stream assignment and/or examples are
required
3.2 Procedures to support the M3UA services in Section 1.4.2 3.2 Procedures to support the M3UA services in Section 1.4.2
3.2.1 Layer Management primitives procedures 3.2.1 Local Layer Management primitives procedures
On receiving these primitives from the local layer management, the M3UA On receiving these primitives from the local layer management, the M3UA
layer will send the corresponding management message (Error) to its layer will send the corresponding management message (Error) to its
peer. The M3UA layer must fill in the various fields of the common and peer. The M3UA layer must fill in the various fields of the common and
specific headers correctly. specific headers correctly.
3.2.2 Receipt of Peer Management messages 3.2.2 Receipt of Peer Management messages
Upon receipt of Management messages, the M3UA layer must invoke the Upon receipt of Management messages, the M3UA layer must invoke the
corresponding Layer Management primitive indications (M-ERROR ind.) to corresponding Layer Management primitive indications (M-ERROR ind.) to
skipping to change at page 29, line 4 skipping to change at page 35, line 9
On receiving these primitives from the local layer management, the M3UA On receiving these primitives from the local layer management, the M3UA
layer will send the corresponding management message (Error) to its layer will send the corresponding management message (Error) to its
peer. The M3UA layer must fill in the various fields of the common and peer. The M3UA layer must fill in the various fields of the common and
specific headers correctly. specific headers correctly.
3.2.2 Receipt of Peer Management messages 3.2.2 Receipt of Peer Management messages
Upon receipt of Management messages, the M3UA layer must invoke the Upon receipt of Management messages, the M3UA layer must invoke the
corresponding Layer Management primitive indications (M-ERROR ind.) to corresponding Layer Management primitive indications (M-ERROR ind.) to
the local layer management. the local layer management.
3.3 Procedures to support the M3UA services in Section 1.4.4 3.3 Procedures to support the M3UA services in Section 1.4.4
These procedures support the M3UA management of SCTP Associations and These procedures support the M3UA management of SCTP Associations
ASP Paths between SGs and ASPs between SGs and ASPs
3.3.1 State Maintenance 3.3.1 State Maintenance
The M3UA layer on the SG needs to maintain the state of each ASP as The M3UA layer on the SG maintains the state of each AS, in each
input to the SGs address translation and mapping function. Appliction Server that it is configured to receive traffic, as input to
the SGs address translation and mapping function.
3.3.1.1 ASP States 3.3.1.1 ASP States
The state of each ASP is maintained in the M3UA layer in the SG. The The state of each ASP, in each AS that it is configured, is maintained
state of an ASP changes due to events. The events include: in the M3UA layer in the SG. The state of a particular ASP in a
particular AS changes due to events. The events include:
* Reception of messages from peer M3UA layer * 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
* Reception of indications from the SCTP layer * Reception of indications from the SCTP layer
* Switch-over Time triggers
The ASP state transition diagram is shown in Figure 4. The possible The ASP state transition diagram is shown in Figure 4. The possible
states of an ASP are: states of an ASP are:
ASP-DOWN: The Application Server Process is unavailable. Initially all ASP-DOWN: The remote M3UA peer at the ASP is unavailable and/or the
ASPs will be in this state. SCTP association is down. Initially all ASPs will be in this state.
ASP-UP: The Application Server Process is available but application ASP-UP: The remote M3UA peer at the ASP is available (and the SCTP
traffic is stopped. association is up) but application traffic is stopped.
ASP-ACTIVE: The Application Server Process is available and application ASP-ACTIVE: The remote M3UA peer at the ASP is available and
traffic is active (for a particular Routing Context or set of Routing application traffic is active (for a particular Routing Context or set
Contexts). of Routing Contexts).
ASP-ACT-OLD: The remote M3UA peer at the ASP is available and
application traffic is active (for a particular Routing Context or set
of Routing Contexts), but for draining of current call/transactions
only (i.e., no new calls/transactions)
ASP-ACT-NEW: The remote M3UA peer at the ASP is available and
application traffic is active (for a particular Routing Context or set
of Routing Contexts), but for new calls/transactions only (i.e., not
for traffic related to completing calls/transactions in another ASP).
Figure 4: ASP State Transition Diagram Figure 4: ASP State Transition Diagram
+-------------+ +-------------+
|-------->| | |----------------------| |
| | ASP-ACTIVE | | Some other /| ASP-ACTIVE |<--------\
| +-------------+ | ASP / +-------------+ |
| ^ | | Takeover / ^ | | Ts
| ASP | | ASP | / ASP | | ASP |
| Active | | Inactive | / Active | | Inactive |
| | v | v | v |
| +-------------+ | +-------------+ +-------------+ +-------------+
ASP Down / | | | | | | | | | |
SCTP CDI | | ASP-UP | | | ASP-ACT-OLD |----->| ASP-UP |------>| ASP-ACT-NEW |
| +-------------+ | +-------------+ Ts / +-------------+ ASP +-------------+
| ^ | | | ASP Inactive ^ | Takeover |
| ASP | | ASP Down / |<---| | | |
| Up | | SCTP CDI | | | |
| | v ASP Down/ | ASP | | ASP Down / | ASP
| +-------------+ SCTP CDI | Up | | SCTP CDI | Down/
| | | | | v | SCTP
|-------->| | | +-------------+ | CDI
| | | |
|------------------>| |<-------------|
| ASP-DOWN | | ASP-DOWN |
+-------------+ +-------------+
SCTP CDI: The local SCTP layer's Communication Down Indication to the SCTP CDI: The local SCTP layer's Communication Down Indication to the
Upper Layer Protocol (M3UA) on an SG. The local SCTP will send this Upper Layer Protocol (M3UA) on an SG. The local SCTP will send this
indication when it detects the loss of connectivity to the ASP's SCTP indication when it detects the loss of connectivity to the ASP's peer
layer. SCTP layer.
Ts: Switch-over Time Triggers. This timer is configurable by the
Operator on a per AS basis.
3.3.1.2 AS States 3.3.1.2 AS States
The state of the AS is maintained in the M3UA layer on the SG. The state of the AS is maintained in the M3UA layer on the SG.
The state of an AS changes due to events. These events include: The state of an AS changes due to events. These events include:
* ASP state transitions * ASP state transitions
* Recovery timer triggers * Recovery timer triggers
skipping to change at page 31, line 31 skipping to change at page 38, line 19
| AS-UP | | AS-ACTIVE | | AS-UP | | AS-ACTIVE |
| | | | | | | |
| |< -| | | |< -| |
+----------+ \ / +-------------+ +----------+ \ / +-------------+
^ | \ Tr Trigger / ^ | ^ | \ Tr Trigger / ^ |
| | \ at least one / | | | | \ at least one / | |
| | \ ASP in UP / | | | | \ ASP in UP / | |
| | \ / | | | | \ / | |
| | \ / | | | | \ / | |
| | \ /---/ | | | | \ /---/ | |
one ASP | | \ / one ASP | | ACTIVE ASP one ASP | | \ / one ASP | | Last ACTIVE ASP
trans | | all ASP \-/----\ trans to | | trans to UP or trans | | all ASP \-/----\ trans to | | trans to UP or
to UP | | trans to / \ ACTIVE | | DOWN to UP | | trans to / \ ACTIVE | | DOWN
| | DOWN / \ | | | | DOWN / \ | |
| | / \ | | | | / \ | |
| | / \ | | | | / \ | |
| | /all ASP \ | | | | /all ASP \ | |
| v / trans to \ | v | v / trans to \ | v
+----------+ / DOWN \ +-------------+ +----------+ / DOWN \ +-------------+
| |<--/ -| | | |<--/ -| |
| AS-DOWN | | AS-PENDING | | AS-DOWN | | AS-PENDING |
| | | (queueing) | | | | (queueing) |
| |<------------------------| | | |<------------------------| |
+----------+ Tr Trigger no ASP +-------------+ +----------+ Tr Trigger no ASP +-------------+
in UP state or in UP state
Tr = Recovery Timer Tr = Recovery Timer
3.3.2 ASPM procedures for primitives 3.3.2 ASPM procedures for primitives
Before the establishment of an SCTP association the ASP state at both Before the establishment of an SCTP association the ASP state at both
the SG and ASP is assumed to be "Down". the SG and ASP is assumed to be "Down".
When the M3UA layer receives an M-SCTP ESTABLISH request primitive from As the ASP is responsible for initiating the setup of an SCTP
the Layer Management, the M3UA layer will try to establish an SCTP association to an SG, the M3UA layer at an ASP receives an M-SCTP
association with the remote M3UA peer. Upon reception of an eventual ESTABLISH request primitive from the Layer Management, the M3UA layer
SCTP-Communication Up confirm primitive from the SCTP, the M3UA layer will try to establish an SCTP association with the remote M3UA peer at
will invoke the primitive M-SCTP ESTABLISH confirm to the Layer an SG. Upon reception of an eventual SCTP-Communication Up confirm
Management. primitive from the SCTP, the M3UA layer will invoke the primitive M-
SCTP ESTABLISH confirm to the Layer Management.
Alternatively, if the remote M3UA-peer establishes the SCTP association At the SG, the M3UA layer will receive an SCTP Communication Up
first, the M3UA layer will receive an SCTP Communication Up indication indication primitive from the SCTP. The M3UA layer will then invoke the
primitive from the SCTP. The M3UA layer will then invoke the primitive primitive M-SCTP ESTABLISH indication to the Layer Management.
M-SCTP ESTABLISH indication to the Layer Management.
Once the SCTP association is established, The M3UA layer at an ASP will Once the SCTP association is established, The M3UA layer at an ASP will
then find out the state of its local M3UA-user from the Layer then find out the state of its local M3UA-user from the Layer
Management using the primitive M-ASP STATUS. Based on the status of Management using the primitive M-ASP STATUS. Based on the status of
the local M3UA-User, the local ASP M3UA Application Server Process the local M3UA-User, the local ASP M3UA Application Server Process
Maintenance (ASPM) function will initiate the ASPM procedures, using Maintenance (ASPM) function will initiate the ASPM procedures, using
the ASP-Up/-Down/-Active/-Inactive messages to convey the ASP-state to the ASP-Up/-Down/-Active/-Inactive messages to convey the ASP-state to
the SG - see Section 3.3.3. the SG - see Section 3.3.3.
If the M3UA layer subsequently receives an SCTP-Communication Down If the M3UA layer subsequently receives an SCTP-Communication Down
indication from the underlying SCTP layer, it will inform the Layer indication from the underlying SCTP layer, it will inform the Layer
Management by invoking the M-SCTP STATUS indication primitive. The Management by invoking the M-SCTP STATUS indication primitive. The
state of the ASP will be moved to "Down" at both the SG and ASP. state of the ASP will be moved to "Down" at both the SG and ASP.
At an ASP, the Layer Management may try to reestablish the SCTP At an ASP, the Layer Management may try to reestablish the SCTP
association using M-SCTP ESTABLISH request primitive. association using M-SCTP ESTABLISH request primitive.
3.3.3 ASPM procedures for peer-to-peer messages 3.3.3 ASPM procedures for peer-to-peer messages
All ASPM messages are sent on a sequenced stream to ensure ordering.
SCTP stream '0' is used.
3.3.3.1 ASP-Up 3.3.3.1 ASP-Up
[Ed Note: text required to specify what SG does before first ASP-Up After an ASP has successfully established an SCTP association to an SG,
received] the SG waits for the ASP to send an ASP-Up message, indicating that the
ASP M3UA peer is available. The ASP is always the initiator of the
ASP-Up exchange.
The SG will mark the path as up if an explicit ASP UP (ASPUP) message When an ASP-Up message is received at an SG and internally the ASP is
is received and internally the path is allowed to come up (i.e., not in not locked-out for local management reasons, the SG marks the remote
a locked local maintenance state). An ASP UP (ASPUP) message will be ASP as 'Up'. The SG responds with an Notify (ASP-Up) message to the
sent to acknowledge the received ASPUP. The SG will respond to a ASPUP ASP in acknowledgement. The SG sends a Notify (ASP-Up) message in
with a ASPDN message if the path is in a locked maintenance state. response to a received ASP-Up message from the ASP even if the ASP is
already marked as "Up" at the SG.
The SG will send a ASPUP message in response to a received ASPUP If for any local reason the SG cannot respond with an ASP-Up, the SG
message from the ASP even if that path was already marked as UP at the responds to a ASP-Up with a ASP-Down message.
SG.
The paths are controlled by the ASP. The SG will only send ASPUP in At the ASP, the Notify (ASP-Up) message received from the SG is not
response to the reception of a ASPUP message. acknowledged by the ASP. If the ASP does not receive a response from
the SG, or an ASP-Down is received, the ASP may resend ASP-Up messages
every 2 seconds until it receives a Notify (ASP-Up) message from the
SG. The ASP may decide to reduce the frequency (say to every 5
seconds) if a Notify (ASP-Up) is not received after a few tries.
The ASP will send ASPUP messages every 2 seconds until the path comes The ASP must wait for the Notify (ASP-Up) message from the SG before
up (i.e. until it receives a ASPUP message from the SG for that path). sending any ASP traffic control messages (ASPAC or ASPIA) or Data
The ASP may decide to reduce the frequency (say to every 5 seconds) if messages or it will risk message loss. If the SG receives Data
messages before an ASP Up is received, the SG should discard.
the an acknowledgement is not received after a few tries. 3.3.3.2 ASP-Down
The ASP should wait for the ASPUP message from the SG before The ASP will send an ASP-Down to an SG when the ASP is to be removed
transmitting ASP maintenance messages (ASPIA or ASPAC) or M3UA messages from the list of ASPs in all Application Servers that it is a member.
or it will risk message loss. The ASPUP message received from the SG
is not acknowledged by the ASP.
3.3.3.2 ASP Down The SG marks the ASP as "Down" and returns an Notify (ASP-Down) message
to the ASP if one of the following events occur:
The SG will mark the ASP as down and send an ASPDN message to the ASP - an ASP-Down message is received from the ASP,
if one of the following events occur: - another ASPM message is received from the ASP and the SG has
locked out the ASP for management reasons.
- an ASP Down(ASPDN) message is received from the ASP, The SG sends a Notify (ASP-Down) message in response to a received ASP-
- the ASP is locked by local maintenance at the SG. Down message from the ASP even if the ASP is already marked as "Down"
at the SG.
The SG will also send a ASPDN message when the ASP is already down and If the ASP does not receive a response from the SG, the ASP may send
a ASPDN) message is received from the ASP. ASP-Down messages every 2 seconds until it receives a ASP-Down message
from the SG or the SCTP association goes down. The ASP may decide to
reduce the frequency (say to every 5 seconds) if an ASP-Down is not
received after a few tries.
The ASP will send ASPDN whenever it wants to take down a ASP. Since 3.3.3.3 M3UA Version Control
the ASPDN messages to the SG or the ASPDN responses from the SG can be
lost (for example, during fail-over), the MGC can send ASPDN messages
every 2 seconds until the path comes down (i.e. until it receives a
ASPDN message from the SG for that path).
3.3.3.3 ASP Version Control If a ASP-Up message with an unsupported version is received, the
receiving end responds with an Error message, indicating the version
the receiving node supports.
If a ASP Up message with an unknown version is received, the receiving This is useful when protocol version upgrades are being performed in a
end will respond with an Error message. This will indicate to the network. A node upgraded to a newer version should support the older
sender which version the receiving node supports. versions used on other nodes it is communicating with. Because ASPs
initiate the ASP-Up procedure it is assumed that the Error message
would normally come from the SG.
This is useful when protocol version upgrades are being performed. A 3.3.3.4 ASP-Active
node with the newer version should support the older versions used on
other nodes it is communicating with.
The version field in the Error message header associated will indicate Anytime after the ASP has received a Notify (ASP-Up) acknowledgement
the version supported by the node. from the SG, the ASP sends an ASP-Active (ASPAC) to the SG indicating
that the ASP is ready to start processing traffic. In the case where
an ASP is configured/registered to process the traffic for more than
one Application Server across an SCTP association, the ASPAC contains
one or more Routing Contexts to indicate for which Application Servers
the ASPAC applies.
3.3.3.4 ASP Active When an ASP Active (ASPAC) message is received, the SG responds to the
ASP with a Notify message acknowledging that the ASPAC was received and
starts sending traffic for the associated Application Server(s) to that
ASP.
When an ASP Active (ASPAC) message is received, the SG will start There are three modes of Application Server traffic handling in the SG
routing to that ASP. Reception of a ASPAC message overrides any M3UA - Over-ride, Load-balancing and New Traffic. The Type parameter
previous ASPAC messages and results in the ASP associated with the in the ASPAC messge indicates the traffic handling mode used in a
ASPAC message to become the newly active ASP. 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 which
sent the ASPAC. Any previously active ASP in the AS is now considered
Inactive and will no longer receive traffic within the AS. The SG
responds to the ASPAC with a Notify (ASP-Active) message to the ASP.
The SG sends a Notify (ASP-Up) to the previously active ASP in the AS,
after stopping all traffic to the ASP.
In the case of a Loadshare mode AS, reception of an ASPAC message at an
SG 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 loadsharing traffic within an AS to all the
active ASPs is application and network 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), depending on the
requirements of the application and the call/transaction state handling
assumptions of the collection of ASPs in the AS. The SG responds to the
ASPAC with a Notify (ASP-Active) message to the ASP.
In the case of a New Traffic mode AS, reception of an ASPAC message at
an SG causes the direction of traffic to the ASP sending the ASPAC.
However, traffic related to completing calls/transactions in another
ASP is not sent to the new ASP (i.e., new calls/transactions only). How
an SG accomplishes the differentiation of old and new transactions and
any loadsharing of traffic is application and implementation dependent.
The SG responds to the ASPAC with a Notify (ASP-Active_New) message to
the ASP. After a configurable time Ts, the ASP is moved to the ASP-
Active state and a Notify (ASP-Active) is sent to the ASP.
3.3.3.5 ASP Inactive 3.3.3.5 ASP Inactive
When a ASPIA message is received, message transmission to that ASP When an ASP wishes to withdraw from receiving traffic the ASP sends an
ceases. The SG will either discard all incoming messages or start ASP Inactive (ASPIA) to the SG. In the case where an ASP is
buffering the incoming messages for T(r)seconds after which messages configured/registered to process the traffic for more than one
will be discarded. Application Server across an SCTP association, the ASPIA contains one
or more Routing Contexts to indicate for which Application Servers the
ASPIA applies.
If the ASP is down, all of the Paths that were supported by that ASP There are three modes of Application Server traffic handling in the SG
M3UA when withdrawing an ASP from service - Over-ride, Load-balancing
and Graceful Withdrawal. The Type parameter in the ASPIA messge
indicates the mode used in a particular Application Server. If the SG
are, by default, down. determines that the mode indicates in an ASPAC is incompatible with the
traffic handling 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, where normally another ASP has
already taken over the traffic within the AS with an Over-ride ASPAC,
the ASP which sent the ASPIA is already considered by the SG to be
"Inactive". A Notify (ASP_Up) message is resent to the ASP, after
ensuring that all traffic is stopped to the ASP.
In the case of a Loadshare mode AS, the SG moves the ASP to the
"Inactive" state and the AS traffic is re-allocated across the
remaining "active" ASPs per the laoadsharing algorithm currently used
within the AS. A Notify (ASP-Up) message is sent to the ASP after al
traffic is halted to the ASP.
In the case of Graceful Withdrawal, the SG diverts all traffic related
to new calls/transactions to other "active" ASPs and therafter sends
only traffic related to incomplete transactons to the ASP. A Notify
(ASP-Act_Old) is sent to the ASP and the ASP is moved to the
"Active_Old" state. When the outstanding calls/transactions are
drained, or after a configurable time Ts, the SG moves the ASP to the
"Up" state and sends a Notify (ASP-Up) message to the ASP.
If no other ASPs are "Active" in the Application Server, the SG either
discards all incoming messages (except messages related to an
"Active_Old" ASP) for the AS or starts buffering the incoming messages
for T(r)seconds after which messages will be discarded. T(r) is
configurable by the network operator. If the SG receives an ASPAC from
an ASP in the AS before expiry of T(r), the buffered traffic is
directed to the ASP and the timer is cancelled.
3.3.3.6 Notify
In the case where a Notify (AS-Up) message is sent by an SG that now
has no ASPs active to service the traffic, the Notify does not force
the ASP(s) receiving the message to become active. The ASPs remain in
control of what (and when) action is taken.
3.3.3.7 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 transport association (i.e., other than the
SCTP).
Once the ASP sends an ASP-Up message to the SG, the ASP sends Beat
messages periodically, subject to a provisionable timer T(beat). The
SG M3UA, upon receiving a BEAT message from the ASP, responds with a
BEAT message. If no BEAT message (or any other M3UA message), is
received from the ASP within the timer 2*T(beat), the ASP will consider
the remote M3UA as 'Down".
At the ASP, if no BEAT message (or any other M3UA message) is received
from the SG within 2*T(beat), the SG is considered unavailable.
Transmission of BEAT messages is stopped and ASP-Up procedures are used
to re-establish communication with the SG M3UA peer.
Note: Heartbeat related events are not shown in Figure 4 "ASP state
transition diagram".
3.4 Procedures to support the M3UA services in Section 1.4.3 3.4 Procedures to support the M3UA services in Section 1.4.3
3.4.1 At an SG 3.4.1 At an SG
On receiving an MTP-PAUSE, MTP-RESUME, or MTP-STATUS indication On receiving an MTP-PAUSE, MTP-RESUME, or MTP-STATUS indication
primitive from the inter-working function at an SG, the M3UA layer will primitive from the nodal inter-working function at an SG, the SG M3UA
send a corresponding SSNM DUNA, DAVA, SCON, or DUPU message (see layer will send a corresponding SSNM DUNA, DAVA, SCON, or DUPU message
Section 2) to the concerned M3UA peers. The M3UA layer must fill in (see Section 2) to the M3UA peers at concerned ASPs. The M3UA layer
various fields of the common and specific headers correctly. must fill in various fields of the SSNM messages consistently with the
information received in the primitives.
The M3UA address translation and mapping function determines the set of The SG M3UA determines the set of concerned ASPs to be informed based
ASPs to be informed based on the network appearance for which the on the SS7 network partition for which the primitive indication is
indication is relevant. All ASPs configured to send/receive traffic relevant. In this way, all ASPs configured to send/receive traffic
within a particular network appearance are informed. If the SG within a particular network appearance are informed. If the SG
operates within a single network appearance, then all ASPs are operates within a single SS7 network appearance, then all ASPs are
informed. It may be possible to suppress DUPU messages to ASPs that do informed.
not implement an MTP3-User protocol peer for the affected MTP3-User,
but this is not mandatory.
In addition, the DUNA, DAVA, SCON messages need to be sent on a Optionally, the SG M3UA may filter further based on the Affected Point
sequenced stream as these primitives should arrive in order. This is Code in the MTP-PAUSE, MTP-Resume, or MTP-Status indication primitives.
not required for the DUPU message, which may optionally be sent un- In this way ASPs can be informed only of affected destinations to which
sequenced. 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.
3.4.2 At an ASP 3.4.2 At an ASP
At an ASP, upon receiving an SSNM message from the remote M3UA Peer, At an ASP, upon receiving an SSNM message from the remote M3UA Peer,
the M3UA layer invokes the appropriate primitive indications to the the M3UA layer invokes the appropriate primitive indications to the
M3UA-User. Local management is informed but no state is maintained in resident M3UA-Users. Local management is informed.
the M3UA layer.
3.4.3 ASP Auditing
An ASP may optionally initiate an audit procedure in order to enquire
of an SG the availability or 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 or congestion
status of one or more SS7 Destination Point Codes.
The DAUD may be sent by the ASP in the following cases. The DAUD may
be sent unsequenced.
- Periodic. A Timer originally set upon reception of DUVA or SCON
message has expired without a subsequent DAVA, DUVA 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 "Up" or "Active" or has been isolated from an SG
for an extended period. The SG can request the
availabilty/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 a 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 does not maintain
the congestion status of any destinations and therefore 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 in response to a
DAUD may contain more than one Affected Point Code.
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 are not congested. Obviously with the reception
of an DUNA, the routeset to the Affected Destination can not also be
congested.
4.0 Examples of M3UA Procedures 4.0 Examples of M3UA Procedures
4.1 Establishment of Association and Traffic between SGs and ASPs 4.1 Establishment of Association and Traffic between SGs and ASPs
4.1.1 Single ASP in an Application Server ("1+0" sparing) 4.1.1 Single ASP in an Application Server ("1+0" sparing)
An example of the message flows for establishing an active association This scenario shows the example M3UA message flows for the
between an SG and an ASP is shown below. It is assumed that an SCTP 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. association is already set-up.
SG ASP1 SG ASP1
| |
|<---------ASP Up---------| |<---------ASP Up----------|
|-------ASP Up (Ack)----->| |------NTFY (ASP-Up)------>|
| | | - |
|<-------ASP Active-------| |<-------ASP Active--------|
|----ASP Active (Ack)---->| |----NTFY (ASP_Active)---->|
| | | |
4.1.2 Two ASPs in Application Server ("1+1" sparing) 4.1.2 Two ASPs in Application Server ("1+1" sparing)
Establishment of Associations between an SG and Multiple ASPs in the This scenario shows the example M3UA message flows for the
same Application Server (Primary/Back-up case). In this case ASP1 will establishment of traffic between an SG and two ASPs in the same
be the primary ASP for the AS and ASP2 will be a standby in the event Application Server, where ASP1 is configured to be "active" and ASP2 a
of failure of the withdrawal from service of ASP1. ASP could act as a "standby" in the event of communication failure or the withdrawal from
hot, warm, or cold standby depending on the extent to which ASP1 and service of ASP1. ASP2 may act as a hot, warm, or cold standby
ASP2 share call state or can communicate call state under depending on the extent to which ASP1 and ASP2 share call/transaction
failure/withdrawal events. 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.
SG ASP1 ASP2 SG ASP1 ASP2
| | | | | |
|<---------ASP Up---------| | |<--------ASP Up----------| |
|-------ASP Up (Ack)----->| | |-------TFY (ASP-Up)----->| |
| | | | | |
|<------------------------------ASP Up---------------| |<-----------------------------ASP Up----------------|
|-----------------------------ASP Up (Ack)---------->| |----------------------------NTFY (ASP-Up)---------->|
| | | | | |
...
| | | | | |
|<-------ASP Active-------| | |<-------ASP Active-------| |
|----ASP Active (Ack)---->| | |----NTFY(ASP-Active)---->| |
| | | | | |
4.1.3 Two ASPs in an Application Server ("1+1" sparing, load-sharing 4.1.3 Two ASPs in an Application Server ("1+1" sparing, load-sharing
case) case)
This scenario shows a similar case to Section 4.1.2 but where the two
ASPs are brought to "active" and loadshare the traffic load. In this
case, one ASP is sufficient to handle the total traffic load.
SG ASP1 ASP2 SG ASP1 ASP2
| | | | | |
|<---------ASP Up---------| | |<---------ASP Up---------| |
|-------ASP Up (Ack)----->| | |-------NTFY(ASP-Up)----->| |
| | | | | |
|<------------------------------ASP Up---------------| |<------------------------------ASP Up---------------|
|-----------------------------ASP Up (Ack)---------->| |-----------------------------NTFY(ASP Up)---------->|
| | | | | |
...
| | | | | |
|<--ASP Active (Ldshr)----| | |<--ASP Active (Ldshr)----| |
|----ASP Active (Ack)---->| | |----NTFY(ASP-Active)---->| |
| | | | | |
|<----------------------------ASP Active (Ldshr)-----| |<----------------------------ASP Active (Ldshr)-----|
|-----------------------------ASP Active (Ack)------>| |-----------------------------NTFY(ASP-Active)------>|
| | | | | |
4.1.4 Three ASPs in an Application Server ("n+k" sparing, load-sharing 4.1.4 Three ASPs in an Application Server ("n+k" sparing, load-sharing
case) 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).
SG ASP1 ASP2 ASP3 SG ASP1 ASP2 ASP3
| | | | | | | |
|<------ASP Up-------| | | |<------ASP Up-------| | |
|----ASP Up (Ack)--->| | | |----NTFY(ASP-Up)--->| | |
| | | | | | | |
|<--------------------------ASP Up-------| | |<--------------------------ASP Up-------| |
|------------------------ASP Up (Ack)--->| | |------------------------NTFY(ASP-Up)--->| |
| | | | | | | |
|<---------------------------------------------ASP Up--------| |<---------------------------------------------ASP Up--------|
|--------------------------------------------ASP Up (Ack)--->| |--------------------------------------------NTFY(ASP-Up)--->|
| | | | | | | |
...
| | | | | | | |
|<-ASP Act. (Ldshr)--| | | |<-ASP Act. (Ldshr)--| | |
|---ASP Act. (Ack)-->| | | |---NTFY(ASP-Act.)-->| | |
| | | | | | | |
|<--------------------ASP Act. (Ldshr)---| | |<--------------------ASP Act. (Ldshr)---| |
|----------------------ASP Act. (Ack)--->| | |----------------------NTFY(ASP-Act.)--->| |
| | | | | | | |
4.3 ASP Traffic Fail-over Examples 4.2 ASP Traffic Fail-over Examples
4.3.1 (1+1 Sparing, withdrawal of ASP, Back-up Over-ride) 4.2.1 (1+1 Sparing, withdrawal of ASP, Back-up Over-ride)
Following on from the example in Section 4.1.2, and ASP withdraws from Following on from the example in Section 4.1.2, and ASP withdraws from
service: service:
SG ASP1 ASP2 SG ASP1 ASP2
| | | | | |
|<-----ASP Inactive-------| | |<-----ASP Inactive-------| |
|---ASP Inactive (Ack)--->| | |---NTFY(ASP Inactive)--->| |
|----------------------------ASP Active (Optional)-->| |--------------------NTFY(ASP-Inactive) (Optional)-->|
| | | | | |
|<------------------------------ ASP Active----------| |<------------------------------ ASP Active----------|
|-----------------------------ASP Active (Ack)------>| |-----------------------------NTFY(ASP-Active)------>|
| | | |
Note: If the SG detects loss of the M3UA peer (M3UA heartbeat loss or 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 detection of SCTP failure), the initial SG-ASP1 ASP Inactive message
exchange would not occur. exchange would not occur.
4.3.2 (1+1 Sparing, Back-up Over-ride) 4.2.2 (1+1 Sparing, Back-up Over-ride)
Following on from the example in Section 4.1.2, and ASP2 wishes to Following on from the example in Section 4.1.2, and ASP2 wishes to
over-ride ASP1 and take over the traffic: over-ride ASP1 and take over the traffic:
SG ASP1 ASP2 SG ASP1 ASP2
| | | | | |
|<------------------------------ ASP Active----------| |<------------------------------ ASP Active----------|
|-----------------------------ASP Active (Ack)------>| |-----------------------------NTFY(ASP-Active)------>|
| | | |----NTFY(ASP-Inactive)-->|
|------ASP Inactive------>| |
|<--ASP Inactive (Ack)----| |
| | | | | |
4.3.3 (n+k Sparing, Load-sharing case, withdrawal of ASP) 4.2.3 (n+k Sparing, Load-sharing case, withdrawal of ASP)
Following on from the example in Section 4.1.4, and ASP1 withdraws from Following on from the example in Section 4.1.4, and ASP1 withdraws from
service: service:
SG ASP1 ASP2 ASP3 SG ASP1 ASP2 ASP3
| | | | | | | |
|<----ASP Inact.-----| | | |<----ASP Inact.-----| | |
|--ASP Inact. (Ack)->| | | |--NTFY(ASP-Inact.)->| | |
| | | | | | | |
|---------------------------------------ASP Act. (Optional)->| |---------------------------------NTFY(Ins. ASPs)(Optional)->|
| | | | | | | |
|<-----------------------------------------ASP Act. (Ldshr)--| |<-----------------------------------------ASP Act. (Ldshr)--|
|-------------------------------------------ASP Act. (Ack)-->| |-------------------------------------------ASP Act. (Ack)-->|
| | | | | | | |
Note: If the SG detects loss of the M3UA peer (M3UA heartbeat loss or The Notify message to ASP3 is optional, as well as the ASP-Active from
detection of SCTP failure), the first SG-ASP1 ASP Inactive message ASP3. The optional Notify can only 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 loadshare 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. exchange would not occur.
4.4 M3UA/MTP3-User Boundary Examples 4.3 M3UA/MTP3-User Boundary Examples
4.4.1 At an ASP 4.3.1 At an ASP
This section describes the primitive mapping from the MTP3 User to M3UA This section describes the primitive mapping from the MTP3 User to M3UA
at an ASP. at an ASP.
4.4.1.1 Support for MTP-Transfer 4.3.1.1 Support for MTP-Transfer on the ASP
When the MTP3-User has data to send into the SS7 network, it will use 4.3.1.1.1 Support for MTP-Transfer Request
the MTP-Transfer indication primitive. The M3UA on the ASP will do the When the MTP3-User on the ASP has data to send into the SS7 network, it
following when it receives an MTP-Transfer: 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 SG
? Determine the correct association to the chosen SG - Determine the correct association to the chosen SG
? Determine the correct stream in the association (e.g., based on SLS) - Determine the correct stream in the association (e.g., based on
SLS)
? Map the MTP-Transfer into the Payload of a Data message - Determine whether to complete the optional fields of the Data
message
? Send the Data message to the remote M3UA peer, over the SCTP - Map the MTP-Transfer Request primitive into the Protocol Data
association field of an m3ua Data message
- Send the Data message to the remote M3UA peer in the SG, over the
SCTP association
SG ASP SG ASP
| | | |
|<-----Data Message-------|<--MTP-Transfer req. |<-----Data Message-------|<--MTP-Transfer req.
| | | |
or 4.3.1.1.2 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 ind.? |------Data Message------>|---MTP-Transfer ind.?
| | | |
4.4.1.2 Support for ASP Querying of SS7 Destination States 4.3.1.1.3 Support for ASP Querying of SS7 Destination States
There are situations such as temporary loss of connectivity to the SG There are situations such as temporary loss of connectivity to the SG
that may cause the M3UA on the ASP to audit SS7 destination that may cause the M3UA on the ASP to audit SS7 destination
availability states. Note: there is no primitive for the MTP3-User to 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 request this audit from the M3UA as this is initiated by an internal
M3UA management function. M3UA management function.
The M3UA on the MGC / AN would send Destination State Audit (DAUD) The M3UA on the ASP normally sends Destination State Audit (DAUD)
messages for each of the destinations that the MGC / AN supports. messages for each of the destinations that the ASP supports.
SG ASP SG ASP
| | | |
|<-----DAUD Message ------| |<-----DAUD Message ------|
|<-----DAUD Message ------| |<-----DAUD Message ------|
|<-----DAUD Message ------| |<-----DAUD Message ------|
| | | |
| | | |
4.4.2 At an SG 4.3.2 At an SG
This section describes the primitive mapping from the MTP3 Upper layer This section describes the MTP3 upper layer primitive mapping to the
boundary to the M3UA at the SG. M3UA at the SG.
4.3.2.1 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------|
| |
4.3.2.2 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 S>G 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------>|
| |
4.3.2.3 Support for MTP-PAUSE, MTP-RESUME, MTP-STATUS
The MTP-PAUSE, MTP-RESUME and MTP-STATUS indication primitives from the 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 MTP3 upper layer interface at the SG need to be made available to the
remote MTP3-User lower layer interface at the ASP. remote MTP3 User Part lower layer interface at the concerned ASP(s).
4.4.2.1 Destination Unavailable 4.3.2.3.1 Destination Unavailable
The MTP3 on the SG will generate an MTP-PAUSE primitive when it The MTP3 on the SG will generate an MTP-PAUSE primitive when it
determines locally that an SS7 destination is unreachable. The M3UA determines locally that an SS7 destination is unreachable. The M3UA
will map this primitive to a Destination Unavailable (DUNA) message. will map this primitive to a Destination Unavailable (DUNA) message.
It will determine which ASP(s) to send the DUNA based on the Network It will determine which ASP(s) to send the DUNA based on the Network
Appearance information. Appearance information.
SG ASP SG ASP
| | | |
--MTP-PAUSE ind.-->|------DUNA Message ----->|--MTP-PAUSE ind.--> --MTP-PAUSE ind.-->|------DUNA Message ----->|--MTP-PAUSE ind.-->
| | | |
4.4.2.2 Destination Available 4.3.2.3.2 Destination Available
The MTP3 on the SG will generate an MTP-RESUME primitive when it The MTP3 on the SG will generate an MTP-RESUME primitive when it
determines locally that an SS7 destination that was previously determines locally that an SS7 destination that was previously
unreachable is now reachable. The M3UA will map this primitive to a unreachable is now reachable. The M3UA will map this primitive to a
Destination Unavailable (DAVA) message. It will determine which ASP(s) Destination Unavailable (DAVA) message. It will determine which ASP(s)
to send the DUNA based on the Network Appearance information. to send the DUNA based on the Network Appearance information.
SG ASP SG ASP
| | | |
--MTP-RESUME ind.-->|------DAVA Message ----->|--MTP-RESUME ind.--> --MTP-RESUME ind.-->|------DAVA Message ----->|--MTP-RESUME ind.-->
| | | |
4.4.2.3 SS7 Network Congestion 4.3.2.3.3 SS7 Network Congestion
The MTP3 on the SG will generate an MTP-STATUS primitive when it The MTP3 on the SG will generate an MTP-STATUS primitive when it
determines locally that the route to an SS7 destination is congested. determines locally that the route to an SS7 destination is congested.
The M3UA will map this primitive to a SS7 Network Congestion State 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 (SCON) message. It will determine which ASP(s) to send the DUPU to
based on the intended Application Server. based on the intended Application Server.
SG ASP SG ASP
| | | |
--MTP-STATUS ind.-->|------SCON Message ----->|--MTP-STATUS ind.--> --MTP-STATUS ind.-->|------SCON Message ----->|--MTP-STATUS ind.-->
| | | |
4.4.2.4 Destination User Part Unavailable 4.3.2.3.4 Destination User Part Unavailable
The MTP3 on the SG will generate an MTP-STATUS primitive when it The MTP3 on the SG will generate an MTP-STATUS primitive when it
determines locally that an SS7 destination User Part is unavailable. determines locally that an SS7 destination User Part is unavailable.
The M3UA will map this primitive to a Destination User Part Unavailable The M3UA will map this primitive to a Destination User Part Unavailable
(DUPU) message. It will determine which ASP(s) to send the DUPU to (DUPU) message. It will determine which ASP(s) to send the DUPU to
based on the intended Application Server. based on the intended Application Server.
SG ASP SG ASP
| | | |
--MTP-STATUS ind.-->|------DUPU Message ----->|--MTP-STATUS ind.--> --MTP-STATUS ind.-->|------DUPU Message ----->|--MTP-STATUS ind.-->
| | | |
5.0 Security 5.0 Security
M3UA relies upon IPSEC to ensure confidentiality of user payload. 5.1 Introduction
Consult [RFC 2401, "Security Architecture for the Internet Protocol",
S. Kent, R. Atkinson, November 1998] for more information on M3UA is designed to carry signaling 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.
5.2 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:
* 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. configuring IPSEC services.
6.0 Acknowledgements 5.3 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.
6.0 IANA Considerations
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 tbd
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.
7.0 Acknowledgements
The authors would like to thank John Loughney, Neil Olson, Norm Glaude, The authors would like to thank John Loughney, Neil Olson, Norm Glaude,
and Michael Tuexen for their valuable comments and suggestions. Michael Tuexen, Nikhil Jain, Steve Lorusso, Dan Brendes, Heinz Prantner
for their valuable comments and suggestions.
7.0 References 8.0 References
[1] RFC 2719, "Framework Architecture for Signaling Transport" [1] RFC 2719, "Framework Architecture for Signaling Transport"
[2] ITU-T Recommendations Q.761 to Q.767, 'Signalling System No.7 (SS7) [2] ITU-T Recommendations Q.761 to Q.767, 'Signalling System No.7 (SS7)
- ISDN User Part (ISUP)' ISDN User Part (ISUP)'
[3] ANSI T1.113 - 'Signaling System Number 7 - ISDN User Part [3] ANSI T1.113 - 'Signaling System Number 7 ISDN User Part
[4] ETSI ETS 300 356-1 "Integrated Services Digital Network (ISDN); [4] ETSI ETS 300 356-1 "Integrated Services Digital Network (ISDN);
Signalling System No.7; ISDN User Part (ISUP) version 2 for the Signalling System No.7; ISDN User Part (ISUP) version 2 for the
international interface; Part 1: Basic services" international interface; Part 1: Basic services"
[5] ITU-T Recommendations Q.711-714, 'Signalling System No. 7 (SS7) - [5] ITU-T Recommendations Q.711-715, 'Signalling System No. 7 (SS7) -
Signalling Connection Control Part (SCCP)' Signalling Connection Control Part (SCCP)'
[6] ANSI T1.112 'Signaling System Number 7 - Signaling Connection [6] ANSI T1.112 'Signaling System Number 7 Signaling Connection
Control Part' Control Part'
[7] ETSI ETS 300 009-1, "Integrated Services Digital Network (ISDN); [7] ETSI ETS 300 009-1, "Integrated Services Digital Network (ISDN);
Signalling System No.7; Signalling Connection Control Part (SCCP) Signalling System No.7; Signalling Connection Control Part (SCCP)
(connectionless and connection-oriented class 2) to support (connectionless and connection-oriented class 2) to support
international interconnection; Part 1: Protocol specification" international interconnection; Part 1: Protocol specification"
[8] ITU-T Recommendations Q.720, 'Telephone User Part' [8] ITU-T Recommendations Q.720, 'Telephone User Part'
[9] ITU-T Recommendation Q.771-775 'Signalling System No. 7 SS7) - [9] ITU-T Recommendation Q.771-775 'Signalling System No. 7 SS7) -
Transaction Capabilities (TCAP) Transaction Capabilities (TCAP)
[10] ANSI T1.114 'Signaling System Number 7 - Transaction Capabilities [10] ANSI T1.114 'Signaling System Number 7 Transaction Capabilities
Application Part' Application Part'
[11] ETSI ETS 300 287-1, "Integrated Services Digital Network (ISDN); [11] ETSI ETS 300 287-1, "Integrated Services Digital Network (ISDN);
Signalling System No.7; Transaction Capabilities (TC) version 2; Signalling System No.7; Transaction Capabilities (TC) version 2;
Part 1: Protocol specification" Part 1: Protocol specification"
[12] RANAP [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] Simple Control Transport Protocol <draft-ietf-sigtran-sctp- [13] Simple Control Transport Protocol <draft-ietf-sigtran-sctp-
05.txt>, Dec. 1999, Work in Progress 05.txt>, Dec. 1999, Work in Progress
[14] ITU-T Recommendations Q.701-Q.705, 'Signalling System No. 7 (SS7) [14] ITU-T Recommendations Q.701-Q.705, 'Signalling System No. 7 (SS7)
- Message Transfer Part (MTP)' - Message Transfer Part (MTP)'
[15] ANSI T1.111 'Signalling System Number 7 - Message Transfer Part' [15] ANSI T1.111 'Signalling System Number 7 - Message Transfer Part'
[16] ETSI ETS 300 008-1, "Integrated Services Digital Network (ISDN); [16] ETSI ETS 300 008-1, "Integrated Services Digital Network (ISDN);
skipping to change at line 1959 skipping to change at page 55, line 7
Interface (SSCF at NNI) Interface (SSCF at NNI)
[18] ITU-T Recommendation Q.2110 'B-ISDN ATM Adaptation Layer - Service [18] ITU-T Recommendation Q.2110 'B-ISDN ATM Adaptation Layer - Service
Specific Connection Oriented Protocol (SSCOP) Specific Connection Oriented Protocol (SSCOP)
[19] MTP2-User Adaptation Layer <draft-ietf-sigtran-m2ua-01.txt>, Nov. [19] MTP2-User Adaptation Layer <draft-ietf-sigtran-m2ua-01.txt>, Nov.
1999, Work in Progress 1999, Work in Progress
[20] ITU-T Recommendation Q.2210 'B-ISDN MTP' [20] ITU-T Recommendation Q.2210 'B-ISDN MTP'
5.0 Author's Addresses [21] RFC 2196, "Site Security Handbook", B. Fraser Ed., September 1997
Lyndon Ong Guy Mousseau [22] RFC 2401, "Security Architecture for the Internet Protocol", S.
Nortel Networks Nortel Networks Kent, R. Atkinson, November 1998.
4401 Great America Pkwy 3685 Richmond Rd
Santa Clara, CA, USA 95054 Nepean, Ontario, Canada K2H 5B7 9.0 Author's Addresses
Lyndon Ong
Nortel Networks
4401 Great America Pkwy
Santa Clara, CA, USA 95054
long@nortelnetworks.com long@nortelnetworks.com
Greg Sidebottom Ian Rytina Greg Sidebottom
Nortel Networks Ericsson Australia Nortel Networks
3685 Richmond Rd, 37/360 Elizabeth Street 3685 Richmond Rd,
Nepean, Ontario, Canada K2H 5B7 Melbourne, Vic 3000 Australia Nepean, Ontario, Canada K2H 5B7
gregside@nortelnetworks.com ian.rytina@ericsson.com gregside@nortelnetworks.com
Hanns Juergen Schwarzbauer Ken Morneault Guy Mousseau
SIEMENS AG Cisco Systems Inc. Nortel Networks
Hofmannstr. 51 13615 Dulles Technology Rd 3685 Richmond Rd
81359 Munich, Germany Herndon, VA 20171 USA Nepean, Ontario, Canada K2H 5B7
HannsJuergen.Schwarzbauer@icn.siemens.de kmorneau@cisco.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
Ken Morneault
Cisco Systems Inc.
13615 Dulles Technology Drive
Herndon, VA, USA 20171
EMail: kmorneau@cisco.com
Malleswar Kalla Malleswar Kalla
Telcordia Technologies Telcordia Technologies
MCC 1J211R MCC 1J211R
445 South Street 445 South Street
Morristown, NJ, USA 07960 Morristown, NJ, USA 07960
EMail: kalla@research.telcordia.com EMail: kalla@research.telcordia.com
This draft expires July 2000. This draft expires September 2000.
 End of changes. 

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