Network Working Group                                      K. Morneault
INTERNET-DRAFT                                            Cisco Systems

Expires in six months                                         July                                          Oct 2002

                  IUA (RFC 3057) Outstanding Issues
            <draft-ietf-sigtran-iua-imp-guide-01.txt>
            <draft-ietf-sigtran-iua-imp-guide-02.txt>

Status of This Memo

    This document is an Internet-Draft and is in full conformance with
    all provisions of Section 10 of RFC 2026 [RFC2026]. Internet-Drafts
    are working documents of the Internet Engineering Task Force (IETF),
    its areas, and its working groups. Note that other groups may also
    distribute working documents as Internet-Drafts.

    The list of current Internet-Drafts can be accessed at
    http://www.ietf.org/ietf/1id-abstracts.txt

    The list of Internet-Draft Shadow Directories can be accessed at
    http://www.ietf.org/shadow.html.

Abstract

   This document captures problems and issues discovered on the SIGTRAN
   mailing list and at future bakeoffs interops for IUA [RFC3057].  This document
   will be updated after each bakeoff interop augmenting the existing draft to
   include any new issues discovered during inter-operability testing.
   Two basic sets of problems are identified by this draft: first, issues
   that need to be addressed when the next revision of IUA is created,
   i.e.  issues that should be remembered in a BIS document; second,
   issues that were found that are strictly implementation problems.

Table of Contents

   1.0 Introduction................................................ 2
   2.0 Conventions................................................. 2
   3.0 Corrections to IUA [RFC3057]................................ 3
   4.0 Acknowledgements............................................12
   5.0 Authors Addresses...........................................13
   6.0 References..................................................13

1. Introduction

   This document contains a compilation of all defects found up until
   May 2002 for the ISDN User Adaptation Layer (IUA) [RFC3057]. These
   defects may be of an editorial or technical nature. This document may
   be thought of as a companion document to be used in the
   implementation of IUA to clarify errors in the original IUA
   document. This document updates RFC3057 and text within this
   document, where noted, supersedes the text found in RFC3057. Each
   error will be detailed within this document in the form of:

      - The problem description,
      - The text quoted from RFC3057,
      - The replacement text,
      - A description of the solution.

2. Conventions

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

3. Corrections to IUA [RFC3057]

3.1 Message Length in Common Header

3.1.1  Description of the problem

   The RFC was not clear if message length in common header should
   include padding bytes.

3.1.2  Text changes to the document

   ---------
   Old text: (Section 3.1.4)
   ---------

   The Message length defines the length of the message in octets,
   including the Common header.

   ---------
   New text: (Section 3.2)
   ---------

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

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

3.1.3 Solution description

   The message length must include padding bytes.

3.2 ASP Down Reason

3.2.1  Description of the problem

   There is a need to synchronize IUA with other UAs by removing Reason
   parameter from ASP Down and ASP Down Ack messages.  The other UAs
   removed the Reason parameter because a use could not be found for
   this parameter.

3.2.2  Text changes to the document

   ---------
   Old text: (Section 3.3.2.3)
   ---------

   The ASPDN message contains the following parameters:

      Reason
      INFO String (Optional)

   The format for the ASPDN message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xa)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Reason                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                         INFO String*                          |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format and description of the optional Info String parameter is
   the same as for the ASP Up message (See Section 3.3.3.1.).

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

      Value         Description
      0x1          Management Inhibit

   If a ASP is removed from Management Inhibit, the ASP will send an ASP
   Up message.

   ---------
   New text: (Section 3.3.2.3)
   ---------

   The ASPDN message contains the following parameters:

      INFO String (Optional)

   The format for the ASPDN message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                         INFO String*                          |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format and description of the optional Info String parameter is
   the same as for the ASP Up message (See Section 3.3.2.1).

   ---------
   Old text: (Section 3.3.2.4)
   ---------

   The ASP Down Ack message is used to acknowledge an ASP Down message
   received from a remote IUA peer.

   The ASP Down Ack message contains the following parameters:

      Reason
      INFO String (Optional)

   The format for the ASP Down Ack message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xa)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Reason                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                         INFO String*                          |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format and description of the optional Info String parameter is
   the same as for the ASP Up message (See Section 3.3.2.1.).

   The format of the Reason parameter is the same as for the ASP Down
   message (See Section 3.3.2.3).

   ---------
   New text: (Section 3.3.2.4)
   ---------

   The ASP Down Ack message is used to acknowledge an ASP Down message
   received from a remote IUA peer.

   The ASP Down Ack message contains the following parameters:

      INFO String (Optional)

   The format for the ASP Down Ack message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                         INFO String*                          |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format and description of the optional Info String parameter is
   the same as for the ASP Up message (See Section 3.3.2.1).

3.2.3 Solution description

   The Reason parameter is removed from the ASP Down and ASP Down
   Acknowledge messages.  ASP and SG implementations should accept the
   respective message without the Reason parameter.

3.3 ASP State Machine

3.3.1  Description of the problem

   Handling of ASP Up when in ASP-ACTIVE state and SCTP Restart
   indication are not specified.

3.3.2  Text changes to the document

   ---------
   Old text: (Section 4.3.1.1)
   ---------

                   Figure 7  ASP State Transition Diagram

                                    +-------------+
             +----------------------|             |
             |   Alternate  +-------| ASP-ACTIVE  |
             |       ASP    |       +-------------+
             |    Takeover  |           ^     |
             |              |    ASP    |     | ASP
             |              |    Active |     | Inactive
             |              |           |     v
             |              |       +-------------+
             |              |       |             |
             |              +------>|  ASP-INACT  |
             |                      +-------------+
             |                          ^    |
   ASP Down/ |                     ASP  |    | ASP Down /
   SCTP CDI  |                     Up   |    | SCTP CDI
             |                          |    v
             |                      +-------------+
             +--------------------->|             |
                                    |  ASP-DOWN   |
                                    +-------------+

   SCTP CDI:  The local SCTP layer's Communication Down Indication to
   the Upper Layer Protocol (IUA) on an SG.  The local SCTP will send
   this indication when it detects the loss of connectivity to the ASP's
   peer SCTP layer.  SCTP CDI is understood as either a SHUTDOWN
   COMPLETE notification and COMMUNICATION LOST notification from the
   SCTP.

   ---------
   New text: (Section 4.3.1.1)
   ---------

                   Figure 7  ASP State Transition Diagram

                                    +--------------+
             +----------------------|              |
             |   Alternate  +-------|  ASP-ACTIVE  |
             |       ASP    |       +--------------+
             |    Takeover  |           ^     |
             |              |    ASP    |     | ASP Inactive /
             |              |    Active |     | ASP Up
             |              |           |     v
             |              |       +--------------+
             |              |       |              |
             |              +------>| ASP-INACTIVE |
             |                      +--------------+
             |                          ^    |
   ASP Down/ |                     ASP  |    | ASP Down /
   SCTP CDI/ |                     Up   |    | SCTP CDI /
   SCTP RI   |                          |    v SCTP RI
             |                      +--------------+
             +--------------------->|              |
                                    |   ASP-DOWN   |
                                    +--------------+

   SCTP CDI:  The local SCTP layer's Communication Down Indication to
   the Upper Layer Protocol (IUA) on an SG.  The local SCTP will send
   this indication when it detects the loss of connectivity to the ASP's
   peer SCTP layer.  SCTP CDI is understood as either a SHUTDOWN
   COMPLETE notification and COMMUNICATION LOST notification from the
   SCTP.

   SCTP RI: The local SCTP layer's Restart indication to the upper
   layer protocol (IUA) on an SG.  The local SCTP will send this
   indication when it detects a restart from the ASP's peer SCTP layer.

3.3.3 Solution description

   A SCTP Restart Indication is treated the same as a Communication
   Down Indication with respect to the ASP state machine on the SG.

   If the SG receives an ASP Up from an ASP in the ASP-ACTIVE state, it
   should sends an ASP Up Acknowledgement and transition the ASP  to the
   ASP-INACTIVE state.

3.4 AS State Machine

3.4.1  Description of the problem

   The AS state machine in the RFC has some editorial errors in the area
   of naming ASP states.

3.4.2  Text changes to the document

   ---------
   Old text: (Section 4.3.1.2)
   ---------

                 Figure 8  AS State Transition Diagram

        +----------+  one ASP trans ACTIVE   +-------------+
        |          |------------------------>|             |
        | AS-INACT |                         |  AS-ACTIVE  |
        |          |                         |             |
        |          |<                        |             |
        +----------+ \                       +-------------+
           ^   |      \ Tr Trigger                ^    |
           |   |       \ at least one             |    |
           |   |        \ ASP in UP               |    |
           |   |         \                        |    |
           |   |          \                       |    |
           |   |           \                      |    |
   one ASP |   |            \            one ASP  |    | Last ACTIVE ASP
   trans   |   | all ASP     \------\    trans to |    | trans to INACT
   to      |   | trans to            \   ACTIVE   |    | or DOWN
   INACT   |   | DOWN                 \           |    | (start Tr timer)
           |   |                       \          |    |
           |   |                        \         |    |
           |   |                         \        |    |
           |   v                          \       |    v
        +----------+                       \ +-------------+
        |          |                        -|             |
        | AS-DOWN  |                         | AS-PENDING  |
        |          |                         |  (queueing) |
        |          |<------------------------|             |
        +----------+    Tr Expiry and no     +-------------+
                       ASP in INACTIVE state

      Tr = Recovery Timer

   ---------
   New text: (Section 4.3.1.2)
   ---------

                 Figure 8: AS State Transition Diagram

      +----------+ one ASP trans to ASP-ACTIVE +-------------+
      |    AS-   |---------------------------->|     AS-     |
      | INACTIVE |                             |   ACTIVE    |
      |          |<---                         |             |
      +----------+    \                        +-------------+
         ^   |         \ Tr Expiry,                ^    |
         |   |          \ at least one             |    |
         |   |           \ ASP in ASP-INACTIVE     |    |
         |   |            \                        |    |
         |   |             \                       |    |
         |   |              \                      |    |
 one ASP |   | all ASP       \            one ASP  |    | Last ACTIVE
 trans   |   | trans to       \           trans to |    | ASP trans to
 to      |   | ASP-DOWN        -------\   ASP-     |    | ASP-INACTIVE
 ASP-    |   |                         \  ACTIVE   |    | or ASP-DOWN
 INACTIVE|   |                          \          |    |  (start Tr)
         |   |                           \         |    |
         |   |                            \        |    |
         |   v                             \       |    v
      +----------+                          \  +-------------+
      |          |                           --|             |
      | AS-DOWN  |                             | AS-PENDING  |
      |          |                             |  (queueing) |
      |          |<----------------------------|             |
      +----------+    Tr Expiry and no ASP     +-------------+
                     in ASP-INACTIVE state)

     Tr = Recovery Timer

3.4.3 Solution description

   The AS state machine is clarified by providing the correct ASP
   state names.

3.5 Remove Notify (AS Down)

3.5.1  Description of the problem

   If AS transitions to AS-DOWN, there are no ASPs to send Notify
   message.  Therefore, there is no need for "Notify (AS Down)".

3.5.2  Text changes to the document

   ---------
   Old text: (Section 3.3.3.2)
   ---------

   The Status Identification 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
   Identification values are used:

      Value          Description
        1    Application Server Down (AS_Down)
        2    Application Server Inactive (AS_Inactive)
        3    Application Server Active (AS_Active)
        4    Application Server Pending (AS_Pending)

   ---------
   New text: (Section 3.3.3.2)
   ---------

   The Status Identification 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
   Identification values are used:

      Value          Description
        1    Reserved
        2    Application Server Inactive (AS-INACTIVE)
        3    Application Server Active (AS-ACTIVE)
        4    Application Server Pending (AS-PENDING)

3.5.3 Solution description

   Removed Notify (AS-DOWN).

3.6 List Tag Values

3.6.1  Description of the problem

   To improve readability, list the parameter values in one place.

3.6.2  Text changes to the document

   ---------
   Old text: (Section 3.1.5)
   ---------

   Parameter Tag: 16 bits (unsigned integer)

   The Tag field is a 16 bit identifier of the type of parameter.  It
   takes a value of 0 to 65534.

   ---------
   New text: (Section 3.1.5)
   ---------

   Parameter Tag: 16 bits (unsigned integer)

   The Tag field is a 16-bit identifier of the type of parameter. It
   takes a value of 0 to 65534.  Common parameters used by adaptation
   layers are in the range of 0x00 to 0x3f.   The parameter Tags defined
   are as follows:

   Common Parameters.  These TLV parameters are common across the
   different adaptation layers:

   Parameter Name                     Parameter ID
   ==============                     ============
   Reserved                              0x0000
   Interface Identifier (integer)        0x0001
   Not Used in IUA                       0x0002
   Interface Identifier (text)           0x0003
   INFO String                           0x0004
   DLCI                                  0x0005
   Not Used in IUA                       0x0006
   Diagnostic Information                0x0007
   Interface Identifer Range             0x0008
   Heartbeat Data                        0x0009
   Not Used in IUA                       0x000a
   Traffic Mode Type                     0x000b
   Error Code                            0x000c
   Status                                0x000d
   Protocol Data                         0x000e
   Release Reason                        0x000f
   TEI Status                            0x0010
   ASP Identifier                        0x0011
   Not Used in IUA                       0x0012 - 0x003f

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

3.6.3 Solution description

   Add a list of parameter tags.

3.7 Add ASP Identifier

3.7.1  Description of the problem

   Add ASP Identifier parameter to ASP Up and Notify messages along
   with associated procedures for using ASP Identifier.  This change
   further aligns IUA with the other UAs.

3.7.2  Text changes to the document

   ---------
   Old text: (Section 3.3.2.1)
   ---------

   The ASPUP message contains the following parameters:

     Info String (optional)

   The format for ASPUP Message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   ---------
   New text: (Section 3.3.2.1)
   ---------

   The ASPUP message contains the following parameters:

     ASP Identifier                Optional
     Info String                   Optional

   The format for ASPUP Message parameters is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0011          |           Length = 8          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         ASP Identifier                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   ASP Identifier: 32-bit unsigned integer

   The optional ASP Identifier parameter contains a unique value that
   is locally significant among the ASPs that support an AS. The SG
   should save the ASP Identifier to be used, if necessary, with the
   Notify message (see Section 3.8.2).

   ---------
   Old text: (Section 3.3.3.1)
   ---------

   None

   ---------
   New text: (Section 3.3.3.1)
   ---------

     0x0e      ASP Identifier Required
     0x0f      Invalid ASP Identifier

   The "ASP Identifier Required" is sent by a SG in response
   to an ASP Up message which does not contain an ASP Identifier
   parameter when the SG requires one.  The ASP SHOULD resend the
   ASP Up message with an ASP Identifier.

   The "Invalid ASP Identifier" is send by a SG in response
   to an ASP Up message with an invalid (i.e., non-unique) ASP
   Identifier.

   ---------
   Old text: (Section 3.3.3.2)
   ---------

   The Notify message will only use the common message header.  The
   Notify message contains the following parameters:

      Status Type
      Status Identification
      Interface Identifiers (Optional)
      INFO String (Optional)

   The format for the Notify message with Integer-formatted Interface
   Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xd)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Status Type            |    Status Identification      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Tag (0x1=integer)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifiers*                    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Tag (0x8=integer range)    |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           .                                                           .
           .                                                           .
           .                                                           .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier StartN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier StopN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                    of Tag Type 0x1 or 0x8                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   ---------
   New text: (Section 3.3.3.2)
   ---------

   The Notify message will only use the common message header.  The
   Notify message contains the following parameters:

      Status Type
      Status Identification
      ASP Identifier             Optional
      Interface Identifiers      Optional
      INFO String                Optional

   The format for the Notify message with Integer-formatted Interface
   Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xd)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Status Type            |    Status Identification      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Tag = 0x0011           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        ASP Identifier                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Tag (0x1=integer)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifiers*                    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Tag (0x8=integer range)    |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           .                                                           .
           .                                                           .
           .                                                           .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier StartN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier StopN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                    of Tag Type 0x1 or 0x8                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.7.3 Solution description

   Added ASP Identifier to provide consistency with other UAs.

3.8 TEI Query

3.8.1  Description of the problem

   There is a need for Q.931 or IUA on the ASP side to query for the
   TEI(s).   This need is based on scenarios (Q.931 restart or ASP
   Override) in which Q.931 or IUA on the ASP side may lose the TEI
   assignment.

3.8.2  Text changes to the document

   ---------
   Old text: (Section 3.1.2)
   ---------

    Management (MGMT) Messages

       0        Error (ERR)
       1        Notify (NTFY)
       2        TEI Status Request
       3        TEI Status Confirm
       4        TEI Status Indication
     5 to 127   Reserved by the IETF
   128 to 255   Reserved for IETF-Defined MGMT extensions

   ---------
   New text: (Section 3.1.2)
   ---------

    Management (MGMT) Messages

       0        Error (ERR)
       1        Notify (NTFY)
       2        TEI Status Request
       3        TEI Status Confirm
       4        TEI Status Indication
       5        TEI Query Request
     6 to 127   Reserved by the IETF
   128 to 255   Reserved for IETF-Defined MGMT extensions

   ---------
   New text: (Section 3.3.3.4)
   ---------

   3.3.3.4 TEI Query Message (Request)

      The TEI Query message is sent by the ASP to query the TEI(s).
      This message consists of the common header and IUA header.
      The DLCI in the IUA header MUST be ignored by the SG.  The
      SG will respond to this message with a TEI Status Indication(s).

3.8.3 Solution description

   A TEI Query message is added to fulfill the need of the ASP
   side to be able to query the TEI value.

3.9 Traffic Mode Text

3.9.1  Description of the problem

   There is a potentially confusing statement in Section 3.3.2.5
   about traffic mode.

3.9.2  Text changes to the document

   ---------
   Old text: (Section 3.3.2.5)
   ---------

   Within a particular Interface Identifier, only one Traffic Mode
   Type can be used.

   ---------
   New text: (Section 3.3.2.5)
   ---------

   Within a particular AS, only one Traffic Mode Type can be used.

3.9.3 Solution description

   Provided clarification that Traffic Mode is on a AS basis not
   an Interface Identifier basis.

3.10  Operational Recommendations

3.10.1  Description of the problem

   Operational recommendations should be in an Appendix instead of the
   main body of the RFC.

3.10.2  Text changes to the document

   ---------
   Old text: (Section 1.3.3)
   ---------

   1.3.3  Signaling Network Architecture

   A Signaling Gateway is used to support the transport of Q.921-User
   signaling traffic to one or more distributed ASPs (e.g., MGCs).
   Clearly, the IUA protocol is not designed to meet the performance and
   reliability requirements for such transport by itself.  However, the
   conjunction of distributed architecture and redundant networks does
   allow for a sufficiently reliable transport of signaling traffic over
   IP.  The IUA protocol is flexible enough to allow its operation and
   management in a variety of physical configurations, enabling Network
   Operators to meet their performance and reliability requirements.

   To meet the ISDN signaling reliability and performance requirements
   for carrier grade networks, Network Operators SHOULD ensure that
   there is no single point of failure provisioned in the end-to-end
   network architecture between an ISDN node and an IP ASP.

   Depending of course on the reliability of the SG and ASP functional
   elements, this can typically be met by the provision of redundant
   QOS-bounded IP network paths for SCTP Associations between SCTP End
   Points, and redundant Hosts, and redundant SGs.  The distribution of
   ASPs within the available Hosts is also important.  For a particular
   Application Server, the related ASPs SHOULD be distributed over at
   least two Hosts.

   An example logical network architecture relevant to carrier-grade
   operation in the IP network domain is shown in Figure 2 below:

                                                          Host1
     ********                                         **************
     *      *_________________________________________*  ********  *
     *      *                                _________*  * ASP1 *  *
     *  SG1 *   SCTP Associations           |         *  ********  *
     *      *_______________________        |         *            *
     ********                       |       |         **************
                                    |       |
     ********                       |       |
     *      *_______________________________|
     *      *                       |
     *  SG2 *    SCTP Associations  |
     *      *____________           |
     *      *            |          |                     Host2
     ********            |          |                 **************
                         |          |_________________*  ********  *
                         |____________________________*  * ASP1 *  *
                                                      *  ********  *
                                                      *            *
                                                      **************
                                                              .
                                                              .
                                                              .

                       Figure 2 - Logical Model Example

   For carrier grade networks, the failure or isolation of a particular
   ASP SHOULD NOT cause stable calls to be dropped.  This implies that
   ASPs need, in some cases, to share the call state or be able to pass
   the call state between each other.  However, this sharing or
   communication of call state information is outside the scope of this
   document.

   ---------
   New text: (Section 1.3.3)
   ---------

   None, all text moved to Appendix.  Section and figure numbering
   adjusted accordingly.

3.10.3 Solution description

   Moved operational recommendations to Appendix.

3.11 Character Set for Text-Based Interface Identifier

3.11.1  Description of the problem

   Currently, a character set for the text-based Interface Identifier
   is not specified.

3.11.2  Text changes to the document

   Replace a dated reference from the list with the reference for
   ANSI X3.4-1986.

   ---------
   Old text: (Section 9)
   ---------

   [2] T1S1.7/99-220 Contribution, 'Back-hauling of DSS1 protocol in a
       Voice over Packet Network'

   ---------
   New text: (Section 9)
   ---------

   [2] Coded Character Set--7-Bit American Standard Code for
       Information Interchange, ANSI X3.4-1986.

   ---------
   Old text: (Section 3.2)
   ---------

   The Tag value for the Text-based Interface Identifier is 0x3.  The
   length is variable.

   ---------
   New text: (Section 3.2)
   ---------

   The Tag value for the Text-based [2] Interface Identifier is 0x3.
   The length is variable.

3.11.3 Solution description

   Add reference to 7-bit ASCII character set for text-based Interface
   Identifier.

3.12 References - Normative and Informative

3.12.1  Description of the problem

   The references should be split between normative and informative.

3.12.2  Text changes to the document

   ---------
   Old text: (Section 9)
   ---------

   [1] ITU-T Recommendation Q.920, 'Digital Subscriber signaling System
       No. 1 (DSS1) - ISDN User-Network Interface Data Link Layer -
       General Aspects'

   [2] T1S1.7/99-220 Contribution, 'Back-hauling of DSS1 protocol in a
       Voice over Packet Network'

   [3] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, H.,
       Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
       "Stream Control Transmission Protocol", RFC 2960, October 2000.

   [4] Ong, L., Rytina, I., Garcia, M., Schwarzbauer, H., Coene, L.,
       Lin, H., Juhasz, I., Holdrege, M., and C. Sharp, "Architectural
       Framework for Signaling Transport", RFC 2719, October 1999.

   [5] Fraser, B., "Site Security Handbook", FYI 8, RFC 2196, September
       1997.

   [6] Kent, S. and R. Atkinson, "Security Architecture for the Internet
       Protocol", RFC 2401, November 1998.

   [7] Bradner, s., "Key words for use in RFCs to Indicate Requirement
       Levels", BCP 14, RFC 2119, March 1997.

   [8] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
       Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.

   ---------
   New text: (Section 3.3.2.5)
   ---------

   9.1  Normative

   [1] ITU-T Recommendation Q.920, 'Digital Subscriber signaling System
       No. 1 (DSS1) - ISDN User-Network Interface Data Link Layer -
       General Aspects'

   [2] Coded Character Set--7-Bit American Standard Code for
       Information Interchange, ANSI X3.4-1986.

   9.2  Informative

   [3] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, H.,
       Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
       "Stream Control Transmission Protocol", RFC 2960, October 2000.

   [4] Ong, L., Rytina, I., Garcia, M., Schwarzbauer, H., Coene, L.,
       Lin, H., Juhasz, I., Holdrege, M., and C. Sharp, "Architectural
       Framework for Signaling Transport", RFC 2719, October 1999.

   [5] Fraser, B., "Site Security Handbook", FYI 8, RFC 2196, September
       1997.

   [6] Kent, S. and R. Atkinson, "Security Architecture for the Internet
       Protocol", RFC 2401, November 1998.

   [7] Bradner, s., "Key words for use in RFCs to Indicate Requirement
       Levels", BCP 14, RFC 2119, March 1997.

   [8] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
       Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.

   [9] RFC 2719, "Framework Architecture for Signaling Transport", L. Ong
        et al, October 1999

3.12.3 Solution description

   Separated the references into ormative and informative.

3.13 ASP Up Procedures

3.13.1  Description of the problem

   The ASP Up procedures need to be resynchronized with the other
   UAs.

3.13.2  Text changes to the document

   ---------
   Old text: (Section 4.3.3.1)
   ---------

   After an ASP has successfully established an SCTP association to an
   SG, the SG waits for the ASP to send an ASP Up message, indicating
   that the ASP IUA peer is available.  The ASP is always the initiator
   of the ASP Up exchange.

   When an ASP Up message is received at an SG and internally the remote
   ASP is not considered locked-out for local management reasons, the SG
   marks the remote ASP as "Inactive".  The SG responds with an ASP Up
   Ack message in acknowledgement.  The SG sends an ASP-Up Ack message
   in response to a received ASP Up message even if the ASP is already
   marked as "Inactive" at the SG.

   If for any local reason the SG cannot respond with an ASP Up, the SG
   responds to a ASP Up with a with an ASP-Down Ack message with Reason
   "Management Blocking".

   At the ASP, the ASP Up Ack message received from the SG is not
   acknowledged by the ASP.  If the ASP does not receive a response from
   the SG, or an ASP Down Ack is received, the ASP MAY resend ASP Up
   messages every 2 seconds until it receives a ASP Up Ack message from
   the SG.  The ASP MAY decide to reduce the frequency (say to every 5
   seconds) if an ASP Up Ack is not received after a few tries.

   The ASP MUST wait for the ASP Up Ack message from the SG before
   sending any ASP traffic control messages (ASPAC or ASPIA) or Data
   messages or it will risk message loss.  If the SG receives QPTM, ASP
   Active or ASP Inactive messages before an ASP Up is received, the SG
   SHOULD discard these messages.

   ---------
   New text: (Section 4.3.3.1)
   ---------

   After an ASP has successfully established an SCTP association to an
   SG, the SG waits for the ASP to send an ASP Up message, indicating
   that the ASP IUA peer is available.  The ASP is always the initiator
   of the ASP Up message.  This action MAY be initiated at the ASP by
   an M-ASP_UP request primitive from Layer Management or MAY be
   initiated automatically by an IUA management function.

   When an ASP Up message is received at an SG and internally the
   remote ASP is in the ASP-DOWN state and not considered locked out
   for local management reasons, the SG marks the remote ASP in the
   state ASP-INACTIVE and informs Layer Management with an M-ASP_Up
   indication primitive.  If the SG is aware, via current configuration
   data, which Application Servers the ASP is configured to operate in,
   the SG updates the ASP state to ASP-INACTIVE in each AS that it is
   a member.

   Alternatively, the SG may move the ASP into a pool of Inactive
   ASPs available for future configuration within Application Server(s),
   determined in a subsequent ASP Active procedure.  If the ASP Up
   message contains an ASP Identifier, the SG should save the ASP
   Identifier for that ASP. The SG MUST send an ASP Up Ack message in
   response to a received ASP Up message even if the ASP is already
   marked as ASP-INACTIVE at the SG.

   If for any local reason (e.g., management lockout) the SG cannot
   respond with an ASP Up Ack message, the SG responds to an ASP Up
   message with an Error message with reason "Refused - Management
   Blocking".

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

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

   The ASP must wait for the ASP Up Ack message before sending any
   other IUA messages (e.g., ASP Active).  If the SG receives any other
   IUA messages before an ASP Up message is received (other than ASP
   Down - see Section 4.3.3.2), the SG MAY discard them.

   If an ASP Up message is received and internally the remote ASP is
   in the ASP-ACTIVE state, an ASP Up Ack message is returned, as well
   as an Error message ("Unexpected Message), and the remote ASP state
   is changed to ASP-INACTIVE in all relevant Application Servers.

   If an ASP Up message is received and internally the remote ASP is
   already in the ASP-INACTIVE state, an ASP Up Ack message is returned
   and no further action is taken.

3.13.3 Solution description

   Updated ASP Up procedures based on other UAs.

3.14 ASP Down Procedures

3.14.1  Description of the problem

   The ASP Down procedures need to be resynchronized with the other
   UAs.

3.14.2  Text changes to the document

   ---------
   Old text: (Section 4.3.3.2)
   ---------

   The ASP will send an ASP Down to an SG when the ASP is to be removed
   from the list of ASPs in all Application Servers that it is a member
   and no longer receive any IUA traffic or management messages.

   Whether the ASP is permanently removed from an AS is a function of
   configuration management.

   The SG marks the ASP as "Down" and returns an ASP Down Ack message to
   the ASP if one of the following events occur:

      -  to acknowledge an ASP Down message from an ASP,
      -  to reply to ASPM messages from an ASP which is locked out for
         management reasons.

   The SG sends an ASP Down Ack message in response to a received ASP
   Down message from the ASP even if the ASP is already marked as "Down"
   at the SG.

   If the ASP does not receive a response from the SG, the ASP MAY send
   ASP Down messages every 2 seconds until it receives an ASP Down Ack
   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 Ack is not received after a few tries.

   ---------
   New text: (Section 4.3.3.2)
   ---------

   The ASP will send an ASP Down to an SG when the ASP is to be removed
   from the list of ASPs in all Application Servers that it is a member
   and no longer receive any IUA traffic or management messages.  This
   action MAY be initiated at the ASP by an M-ASP_DOWN request primitive
   from Layer Management or MAY be initiated automatically by an IUA
   management function.

   Whether the ASP is permanently removed from an AS is a function of
   configuration management.

   The SG marks the ASP as ASP-DOWN, informs Layer Management with
   an M-ASP_Down indication primitive, and returns an ASP Down Ack
   message to the ASP.

   The SG MUST send an ASP Down Ack message in response to a received
   ASP Down message from the ASP even if the ASP is already marked as
   ASP-DOWN at the SG.

   At the ASP, the ASP Down Ack message received is not acknowledged.
   Layer Management is informed with an M-ASP_DOWN confirm primitive.
   If the ASP receives an ASP Down Ack without having sent an ASP Down
   message, the ASP should now consider itself as in the ASP-DOWN state.
   If the ASP was previously in the ASP-ACTIVE or ASP-INACTIVE state,
   the ASP should then initiate procedures to return itself to its
   previous state.

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

3.14.3 Solution description

   Updated ASP Down procedures based on other UAs.

3.15 ASP Active Procedures

3.15.1  Description of the problem

   The ASP Active procedures need to be resynchronized with the other
   UAs.

3.15.2  Text changes to the document

   ---------
   Old text: (Section 4.3.3.4)
   ---------

   When an ASP Active (ASPAC) message is received, the SG responds to
   the ASP with a ASPAC Ack message acknowledging that the ASPAC was
   received and starts sending traffic for the associated Application
   Server(s) to that ASP.

   ---------
   New text: (Section 4.3.3.4)
   ---------

   If the Application Server can be successfully activated, the SG
   responds responds to the ASP with a ASPAC Ack message acknowledging
   that the ASPAC was received and starts sending traffic for the
   Application Server to that ASP.

   In the case where an "out-of-the-blue" ASP Active message is
   received  (i.e., the ASP has not registered with the SG or the
   SG has no static configuration data for the ASP), the message
   MAY be silently discarded.

   The SG MUST send an ASP Active Ack message in response to a
   received ASP Active message from the ASP, if the ASP is already
   marked in the ASP-ACTIVE state at the SG.

   At the ASP, the ASP Active Ack message received is not
   acknowledged.  Layer Management is informed with an M-ASP_ACTIVE
   confirm primitive.  It is possible for the ASP to receive Data
   message(s) before the ASP Active Ack message as the ASP Active Ack
   and Data messages from an SG may be sent on different SCTP streams.
   Message loss is possible as the ASP does not consider itself in the
   ASP-ACTIVE state until reception of the ASP Active Ack message.

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

3.15.3 Solution description

   Updated ASP Active procedures based on other UAs.

3.16 ASP Inactive Procedures

3.16.1  Description of the problem

   The ASP Inactive procedures need to be resynchronized with the
   other UAs.

3.16.2  Text changes to the document

   ---------
   Old text: (Section 4.3.3.5)
   ---------

   If no other ASPs are Active in the Application Server, the SG sends a
   NTFY (AS-Pending) to all inactive ASPs of the AS and either discards
   all incoming messages for the AS or starts buffering the incoming
   messages for T(r)seconds, after which messages will be discarded.
   T(r) is configurable by 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.  If T(r)
   expires, the AS is moved to the "Inactive" state.

   ---------
   New text: (Section 4.3.3.5)
   ---------

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

   If no other ASPs in the Application Server are in the state
   ASP-ACTIVE, the SG MUST send a Notify message ("AS-Pending") to
   all of the ASPs in the AS which are in the state ASP-INACTIVE.
   The SG SHOULD start buffering the incoming messages for T(r)
   seconds, after which messages MAY be discarded.  T(r) is
   configurable by the network operator.  If the SG receives an ASP
   Active message from an ASP in the AS before expiry of T(r), the
   buffered traffic is directed to that ASP and the timer is cancelled.
   If T(r) expires, the AS is moved to the AS-INACTIVE state.

   At the ASP, the ASP Inactive Ack message received is not
   acknowledged.  Layer Management is informed with an M-ASP_INACTIVE
   confirm primitive.  If the ASP receives an ASP Inactive Ack without
   having sent an ASP Inactive message, the ASP should now consider
   itself as in the ASP-INACTIVE state.  If the ASP was previously in
   the ASP-ACTIVE state, the ASP should then initiate procedures to
   return itself to its previous state.

3.16.3 Solution description

   Updated ASP Inactive procedures based on other UAs.

3.17 Notify Procedures

3.17.1  Description of the problem

   The Notify procedures need to be resynchronized with the
   other UAs.

3.17.2  Text changes to the document

   ---------
   Old text: (Section 4.3.3.6)
   ---------

   A Notify message reflecting a change in the AS state is sent to all
   ASPs in the AS, except those in the "Down" state, with appropriate
   Status Identification.

   ---------
   New text: (Section 4.3.3.6)
   ---------

   A Notify message reflecting a change in the AS state MUST be sent
   to all ASPs in the AS, except those in the ASP-DOWN state, with
   appropriate Status Information and any ASP Identifier of the
   failed ASP.  At the ASP, Layer Management is informed with an
   M-NOTIFY indication primitive.  The Notify message must be sent
   whether the AS state change was a result of an ASP failure or
   reception of an ASP State management (ASPSM) / ASP Traffic Management
   (ASPTM) message.  In the second case, the Notify message MUST be
   sent after any related acknowledgement messages  (e.g., ASP Up Ack,
   ASP Down Ack, ASP Active Ack, or ASP Inactive Ack).

3.17.3 Solution description

   Updated Notify procedures based on other UAs.

3.18 Heartbeat Text Clarification

3.18.1  Description of the problem

   The are some minor error in the Heartbeat procedures text.

3.18.2  Text changes to the document

   ---------
   Old text: (Section 4.3.3.7)
   ---------

   After receiving an ASP Up Ack message from the SG in response to an
   ASP Up message, the ASP MAY optionally send Beat messages
   periodically, subject to a provisionable timer T(beat).  The SG IUA,
   upon receiving a BEAT message from the ASP, responds with a BEAT ACK
   message.  If no BEAT message (or any other IUA message) is received
   from the SG within the timer 2*T(beat), the SG will consider the
   remote IUA as "Down".  The SG will also send an ASP Down Ack message
   to the ASP.

   ---------
   New text: (Section 4.3.3.7)
   ---------

   Either IUA peer may optionally send Heartbeat messages periodically,
   subject to a provisionable timer T(beat).  Upon receiving a Heartbeat
   message, the IUA peer MUST respond with a Heartbeat Ack message.

   If no Heartbeat Ack message (or any other IUA message) is received
   from the IUA peer within 2*T(beat), the remote IUA peer is
   considered unavailable.  Transmission of Heartbeat messages is
   stopped and the signalling process SHOULD attempt to re-establish
   communication if it is configured as the client for the
   disconnected IUA peer.

3.18.3 Solution description

   Updated Heartbeat procedures based on other UAs.

3.19 Error Message

3.19.1  Description of the problem

   There is a need to add the "Refused - Management Blocking" error
   code.  Need to clearly specify that Error messages are not to be
   sent in response to an Error message.

   Also, need to indicate that the Diagnostic area must be used
   for the Invalid Interface Identifier error.

3.19.2  Text changes to the document

   ---------
   Old text: (Section 3.3.3.1)
   ---------

      Invalid Version                               0x01
      Invalid Interface Identifier                  0x02
      Unsupported Message Class                     0x03
      Unsupported Message Type                      0x04
      Unsupported Traffic Handling Mode             0x05
      Unexpected Message                            0x06
      Protocol Error                                0x07
      Unsupported Interface Identifier Type         0x08
      Invalid Stream Identifier                     0x09
      Unassigned TEI                                0x0a
      Unrecognized SAPI                             0x0b
      Invalid TEI, SAPI combination                 0x0c

   The "Invalid Version" error would be sent if a message was received
   with an invalid or unsupported version.  The Error message would
   contain the supported version in the Common header.  The Error
   message could optionally provide the supported version in the
   Diagnostic Information area.

   The "Invalid Interface Identifier" error would be sent by a SG if an
   ASP sends a message with an invalid (unconfigured) Interface
   Identifier value.

   ---------
   New text: (Section 3.3.3.1)
   ---------

      Invalid Version                               0x01
      Invalid Interface Identifier                  0x02
      Unsupported Message Class                     0x03
      Unsupported Message Type                      0x04
      Unsupported Traffic Handling Mode             0x05
      Unexpected Message                            0x06
      Protocol Error                                0x07
      Unsupported Interface Identifier Type         0x08
      Invalid Stream Identifier                     0x09
      Unassigned TEI                                0x0a
      Unrecognized SAPI                             0x0b
      Invalid TEI, SAPI combination                 0x0c
      Refused - Management Blocking                 0x0d
      ASP Identifier Required                       0x0e
      Invalid ASP Identifier                        0x0f

   The "Invalid Version" error would be sent if a message was received
   with an invalid or unsupported version.  The Error message would
   contain the supported version in the Common header.  The Error
   message could optionally provide the supported version in the
   Diagnostic Information area.

   The "Invalid Interface Identifier" error would be sent by a SG if an
   ASP sends a message with an invalid (unconfigured) Interface
   Identifier value.  For this error, the Diagnostic Information MUST
   contain the Common and IUA message headers of the offending message
   so that Invalid Interface Identifier can be identified.

   Error messages MUST NOT be generated in response to other Error
   messages.

3.19.3 Solution description

   Added new error code and clarified that Error messages must not be
   generated in response to an Error message.  These changes make IUA
   more consistent with other UAs.

3.20 Misconfiguration of Interface Identifiers

3.20.1  Description of the problem

   Provide some examples of how to handle misconfiguration of Interface
   Identifiers.

3.20.2  Text changes to the document

   ---------
   New text: (Section 5.1.5)
   ---------

   This scenario shows the example IUA message flows for the
   establishment of traffic between an SG and an ASP in which some
   of the Interface Identifiers have been misconfigured on the
   ASP side.  The SG in this case has Interface Identifers 1-5
   configured for ASP1.

                SG                               ASP1
                 |                                |
                 |                                |
                 |<----ASP Active (IIDs 1-10)-----|
                 |---ASP Active Ack (IIDs 1-5)--->|
                 |-------Error (IIDs 6)---------->|
                 |-------Error (IIDs 7)---------->|
                 |-------Error (IIDs 8)---------->|
                 |-------Error (IIDs 9)---------->|
                 |-------Error (IIDs 10)--------->|
                 |                                |

3.20.3 Solution description

   An example message flow is provided for the case of Interface
   Identifier misconfiguration.

3.21 ASP Inactive Traffic Mode Parameter

3.21.1  Description of the problem

   The Traffic Mode Type parameter was removed from ASP Inactive
   and ASP Inactive Acknowledgement messages for all other UAs.

3.21.2  Text changes to the document

   ---------
   Old text: (Section 3.3.2.7)
   ---------

   The ASPIA message contains the following parameters

      Traffic Mode Type (Mandatory)
      Interface Identifiers (Optional)
         - Combination of integer and integer ranges, OR
         - string (text formatted)
      INFO String (Optional)

   The format for the ASP Inactive message parameters using Integer
   formatted Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xb)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Traffic Mode Type                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Tag (0x1=integer)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifiers*                    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Tag (0x8=integer range)    |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       .                                                     .
       .                                                     .
       .                                                     .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier StartN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier StopN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                    of Tag Type 0x1 or 0x8                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format for the ASP Inactive message using text formatted (string)
   Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xb)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Traffic Mode Type                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Tag (0x3=string)        |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifier*                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                        of Tag Type 0x3                        |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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

      Value          Description
       0x1            Over-ride
       0x2            Load-share

   ---------
   New text: (Section 3.3.2.7)
   ---------

   The ASPIA message contains the following parameters

      Interface Identifiers (Optional)
         - Combination of integer and integer ranges, OR
         - string (text formatted)
      INFO String (Optional)

   The format for the ASP Inactive message parameters using Integer
   formatted Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Tag (0x1=integer)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifiers*                    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Tag (0x8=integer range)    |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        .                                                      .
        .                                                      .
        .                                                      .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier StartN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier StopN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                    of Tag Type 0x1 or 0x8                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x4)           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format for all other UAs.

3.21.2  Text changes to the document ASP Inactive message using text formatted (string)
   Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Tag (0x3=string)        |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifier*                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                        of Tag Type 0x3                        |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   ---------
   Old text: (Section 3.3.2.7) 3.3.2.8)
   ---------
   The ASP Inactive (ASPIA) Ack message is used to acknowledge an ASP
   Inactive message received from a remote IUA peer.

   The ASPIA Ack message contains the following parameters parameters:

      Traffic Mode Type (Mandatory)
      Interface Identifiers (Optional)
         - Combination of integer and integer ranges, OR
         - string (text formatted)
      INFO String (Optional)

   The format for the ASP Inactive message parameters using Integer
   formatted Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xb)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Traffic Mode Type                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Tag (0x1=integer)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifiers*                    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Tag (0x8=integer range)    |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           .                                                           .
           .                                                           .
           .                                                           .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier StartN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier StopN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                    of Tag Type 0x1 or 0x8                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format for the ASP Inactive Ack message using text formatted
   (string) Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0xb)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Traffic Mode Type                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Tag (0x3=string)        |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifier*                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                        of Tag Type 0x3                        |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Traffic Mode Type parameter identifies the traffic mode of
   operation format of the ASP within an AS.  The valid values for Traffic Mode Type are shown in and Interface Identifier
   parameters is the following table:

      Value          Description
       0x1            Over-ride
       0x2            Load-share same as for the ASP Inactive message (See Section
   3.3.2.7).

   ---------
   New text: (Section 3.3.2.7) 3.3.2.8)
   ---------
   The ASP Inactive (ASPIA) Ack message is used to acknowledge an ASP
   Inactive message received from a remote IUA peer.

   The ASPIA Ack message contains the following parameters parameters:

      Interface Identifiers (Optional)
         - Combination of integer and integer ranges, OR
         - string (text formatted)
      INFO String (Optional)

   The format for the ASP Inactive message parameters using Integer
   formatted Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Tag (0x1=integer)         |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifiers*                    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Tag (0x8=integer range)    |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop1*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier Start2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier Stop2*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           .                                                           .
           .                                                           .
           .                                                           .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier StartN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Interface Identifier StopN*                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                    of Tag Type 0x1 or 0x8                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format for the ASP Inactive Ack message using text formatted
   (string) Interface Identifiers is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Tag (0x3=string)        |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Interface Identifier*                     |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |              Additional Interface Identifiers                 |
   |                        of Tag Type 0x3                        |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag (0x4)             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                          INFO String*                         |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The format of the Interface Identifier parameters is the same as for
   the ASP Inactive message (See Section 3.3.2.7).

3.21.3 Solution description

   Remove Traffic Mode Type from ASP Inactive message in order to
   remain consistent with other UAs.

3.22 Encoding of the DLCI parameter

3.22.1 Description of the problem

  The text states the DLCI field is encoded in accordance to Q.921
  and a figure is given. Using the standard interpretation of the IETF
  for the significance of bits the encoding described in the figure
  is not in accordance to Q.921.

3.22.2 Text changes to the document

  --------
  Old text (Section 3.2)
  --------

3.2 IUA Message Header

   In addition to the common message header, there will be a specific
   message header for QPTM and the TEI Status MGMT messages.  The IUA
   message header will immediately follow the Common header in these
   messages.

   This message header will contain the Interface Identifier and Data
   Link Connection Identifier (DLCI).  The Interface Identifier
   identifies the physical interface terminating the signaling channel
   at the SG for which the signaling messages are sent/received.  The
   format of the Interface Identifier parameter can be text or integer.
   The Interface Identifiers are assigned according to network operator
   policy.  The integer values used are of local significance only,
   coordinated between the SG and ASP.

   The integer formatted Interface Identifier MUST be supported.  The
   text formatted Interface Identifier MAY optionally be supported.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x1)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier (integer)                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x5)           |             Length=8          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            DLCI               |              Spare            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 4 IUA Message Header (Integer-based Interface Identifier)

   The Tag value for the Integer-based Interface Identifier is 0x1.  The
   length is always set to a value of 8.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x3)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Interface Identifier (text)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x5)           |             Length=8          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            DLCI               |             Spare             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 5  IUA Message Header (Text-based Interface Identifier)

   The Tag value for the Text-based Interface Identifier is 0x3.  The
   length is variable.

   The DLCI format is shown below in Figure 6.

      0     1     2     3     4     5     6     7
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |  0  | SPR |      SAPI                         |
   +-----------------------------------------------+
   |  1  |            TEI                          |
   +-----------------------------------------------+

              Figure 6  DLCI Format

   SPR:  Spare 2nd bit in octet 1, (1 bit)

   SAPI: Service Access Point Identifier, 3rd through 8th bits in octet
      1 (6 bits)

   TEI:  Terminal Endpoint Identifier, 2nd through 8th bits in octet 2
      (7 bits)

   The DLCI field (including the SAPI and TEI) is coded in accordance
   with Q.921.

  --------
  New text (Section 3.2)
  --------

3.2 IUA Message Header

   In addition to the common message header, there will be a specific
   message header for QPTM and the TEI Status MGMT messages.  The IUA
   message header will immediately follow the Common header in these
   messages.

   This message header will contain the Interface Identifier and Data
   Link Connection Identifier (DLCI).  The Interface Identifier
   identifies the physical interface terminating the signaling channel
   at the SG for which the signaling messages are sent/received.  The
   format of the Interface Identifier parameter can be text or integer.
   The Interface Identifiers are assigned according to network operator
   policy.  The integer values used are of local significance only,
   coordinated between the SG and ASP.

   The integer formatted Interface Identifier MUST be supported.  The
   text formatted Interface Identifier MAY optionally be supported.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x1)           |             Length=8          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Interface Identifier (integer)                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x5)           |             Length=8          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            DLCI               |              Spare            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 4 IUA Message Header (Integer-based Interface Identifier)

   The Tag value for the Integer-based Interface Identifier is 0x1.  The
   length is always set to a value of 8. The Interface Identifier (integer)
   is a 32-bit unsigned integer.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x3)           |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Interface Identifier (text)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x5)           |             Length=8          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            DLCI               |             Spare             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 5  IUA Message Header (Text-based Interface Identifier)

   The Tag value for the Text-based Interface Identifier is 0x3.  The
   length is variable.

   The DLCI format is shown below in Figure 6.

        most                                     least
     significant                              significant
         bit                                      bit
      +-----+-----+-----+-----+-----+-----+-----+-----+
      |            SAPI                   | SPR |  0  |
      +-----------------------------------------------+
      |            TEI                          |  1  |
      +-----------------------------------------------+

                    Figure 6  DLCI Format

   SPR:  Spare 2nd bit in octet 1, (1 bit)

   SAPI: Service Access Point Identifier, (6 bits)

   TEI:  Terminal Endpoint Identifier, (7 bits)

   As an example SAPI = 0, TEI = 64, SPR = 0 would be encoded as

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Tag (0x5)           |             Length=8          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      0x0      |      0x81     |               0x0             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The DLCI field (including the SAPI and TEI) is coded in accordance
   with Q.921.

3.22.3 Solution description

  It is now clearly stated that the DLCI field is encoded in accordance
  with Q.921.

3.23 Updates to Message Flow Examples

3.23.1 Description of the problem

  The message flow examples in Section 5 were missing Notify
  messages.

3.23.2 Text changes to the document

  --------
  Old text (Section 5.1.1)
  --------

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

  --------
  New text (Section 5.1.1)
  --------

                SG                       ASP1
                 |
                 |<---------ASP Up----------|
                 |--------ASP Up Ack------->|
                 |                          |
                 |-----NTFY(AS-INACTIVE)--->|
                 |                          |
                 |<-------ASP Active--------|
                 |------ASP Active Ack----->|
                 |                          |
                 |------NTFY(AS-ACTIVE)---->|
                 |                          |

  --------
  Old text (Section 5.1.2)
  --------

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

  --------
  New text (Section 5.1.2)
  --------

          SG                        ASP1                        ASP2
           |                         |                          |
           |<--------ASP Up----------|                          |
           |-------ASP Up Ack------->|                          |
           |                         |                          |
           |----NTFY(AS-INACTIVE)--->|                          |
           |---------------------NTFY(AS-INACTIVE)------------->|
           |                         |                          |
           |<-----------------------------ASP Up----------------|
           |----------------------------ASP Up Ack------------->|
           |                         |                          |
           |                         |                          |
           |<-------ASP Active-------|                          |
           |-----ASP Active Ack----->|                          |
           |                         |                          |
           |-----NTFY(AS-ACTIVE)---->|                          |
           |----------------------NTFY(AS-ACTIVE)-------------->|

  --------
  Old text (Section 5.1.3)
  --------

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

  --------
  New text (Section 5.1.3)
  --------

          SG                       ASP1                       ASP2
           |                         |                          |
           |<---------ASP Up---------|                          |
           |--------ASP Up Ack------>|                          |
           |                         |                          |
           |----NTFY(AS-INACTIVE)--->|                          |
           |---------------------NTFY(AS-INACTIVE)------------->|
           |                         |                          |
           |<------------------------------ASP Up---------------|
           |-----------------------------ASP Up Ack------------>|
           |                         |                          |
           |                         |                          |
           |<--ASP Active (Ldshr)----|                          |
           |----ASP Active Ack------>|                          |
           |                         |                          |
           |-----NTFY(AS-ACTIVE)---->|                          |
           |----------------------NTFY(AS-ACTIVE)-------------->|
           |                         |                          |
           |<----------------------------ASP Active (Ldshr)-----|
           |-----------------------------ASP Active Ack-------->|
           |                         |                          |

  --------
  Old text (Section 5.1.4)
  --------

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

  --------
  New text (Section 5.1.4)
  --------

      SG                  ASP1                ASP2                ASP3
       |                    |                   |                   |
       |<------ASP Up-------|                   |                   |
       |-----ASP Up Ack---->|                   |                   |
       |                    |                   |                   |
       |-NTFY(AS-INACTIVE)->|                   |                   |
       |--------------NTFY(AS-INACTIVE)-------->|                   |
       |-----------------------NTFY(AS-INACTIVE)------------------->|
       |                    |                   |                   |
       |<--------------------------ASP Up-------|                   |
       |------------------------ASPUp Ack)----->|
       |-----------------------ASP Up Ack------>|                   |
       |                    |                   |                   |
       |<---------------------------------------------ASP Up--------|
       |--------------------------------------------ASP Up Ack----->|
       |                    |                   |                   |
       |                    |                   |                   |
       |<-ASP Act (Ldshr)---|                   |                   |
       |----ASP Act Ack---->|                   |                   |
       |                    |                   |                   |
       |<---------------------ASP Act (Ldshr)---|                   |
       |----------------------ASP Act Ack------>|                   |
       |                    |                   |                   |
       |--NTFY(AS-ACTIVE)-->|                   |                   |
       |---------------NTFY(AS-ACTIVE)--------->|                   |
       |------------------------NTFY(AS-ACTIVE)-------------------->|

  --------
  Old text (Section 5.2.1)
  --------

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

  --------
  New text (Section 5.2.1)
  --------

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

3.23.3 Solution description

  The new text shows when the SG should send Notify messages.

4.0 Acknowledgements

   The author would like to thank the following people that have
   provided comments and input for this document:  Alex Audu,
   Greg Sidebottom, Srinivasa A. Shikaripura, Subhodeep Sarkar,
   Sujatha Krao, Ming Lin, Shih-Chang Liang and Liang, Michael Tuexen. Tuexen and
   Kameshwar Mallampalli.

5.0 Authors Addresses

   Ken A. Morneault
   13615 Dulles Technology Drive
   Herndon, VA  20171
   USA

   EMail: kmorneau@cisco.com

6.0 References

   [RFC3057] - Morneault K., Rengasami S., Kalla M., Sidebottom G. -
   "ISDN Q.921-User Adaptation (IUA) Protocol", RFC 3057, February
   2001.