Signaling System 7 (SS7) Message Transfer Part 3 (MTP3) - User Adaptation Layer (M3UA)
RFC 3332

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Network Working Group                                      G. Sidebottom
Request for Comments: 3332                         Signatus Technologies
Category: Standards Track                                   K. Morneault
                                                                   Cisco
                                                        J. Pastor-Balbas
                                                                Ericsson
                                                                 Editors
                                                          September 2002

       Signaling System 7 (SS7) Message Transfer Part 3 (MTP3) -
                      User Adaptation Layer (M3UA)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This memo defines a protocol for supporting the transport of any SS7
   MTP3-User signalling (e.g., ISUP and SCCP messages) over IP using the
   services of the Stream Control Transmission Protocol.  Also,
   provision is made for protocol elements that enable a seamless
   operation of the MTP3-User peers in the SS7 and IP domains. This
   protocol would be used between a Signalling Gateway (SG) and a Media
   Gateway Controller (MGC) or  IP-resident Database, or between two
   IP-based applications.  It is assumed that the SG receives SS7
   signalling over a standard SS7 interface using the SS7 Message
   Transfer Part (MTP) to provide transport.

Table of Contents

   1.  Introduction..................................................3
   1.1 Scope.........................................................3
   1.2 Terminology...................................................4
   1.3 M3UA Overview.................................................6
   1.4 Functional Areas.............................................10
   1.5 Sample Configurations........................................18
   1.6 Definition of M3UA Boundaries................................21
   2.  Conventions..................................................25

Sidebottom, et. al.         Standards Track                     [Page 1]
RFC 3332             SS7 MTP3-User Adaptation Layer       September 2002

   3.  M3UA Protocol Elements.......................................25
   3.1 Common Message Header........................................26
   3.2 Variable Length Parameter....................................29
   3.3 Transfer Messages............................................31
   3.4 SS7 Signalling Network Management (SSNM) Messages............35
   3.5 ASP State Maintenance (ASPSM) Messages.......................45
   3.6 Routing Key Management (RKM) Messages........................48
   3.7 ASP Traffic Maintenance (ASPTM) Messages.....................59
   3.8 Management (MGMT) Messages...................................63
   4.  Procedures...................................................69
   4.1 Procedures to Support the M3UA-User .........................69
   4.2 Procedures to Support the Management of SCTP Associations ...70
   4.3 AS and ASP State Maintenance.................................72
   4.4 Routing Key Management Procedures............................87
   4.5 Procedures to Support the Availability or Congestion Status
       of SS7 Destination...........................................89
   4.6 MTP3 Restart.................................................92
   5.  Examples of M3UA Procedures..................................93
   5.1 Establishment of Association and Traffic
       Between SGs and ASPs.........................................93
   5.2 ASP traffic Failover Examples................................99
   5.3 Normal Withdrawal of an ASP from an Application Server
       and Teardown of an Association..............................100
   5.4 M3UA/MTP3-User Boundary Examples............................101
   5.5 Examples of IPSP communication..............................105
   6.  Security Considerations.....................................108
   6.1 Introduction................................................108
   6.2 Threats.....................................................108
   6.3 Protecting Confidentiality..................................108
   7.  IANA Considerations.........................................109
   7.1 SCTP Payload Protocol Identifier............................109
   7.2 M3UA Port Number............................................109
   7.3 M3UA Protocol Extensions....................................109
   8. References...................................................111
   8.1 Normative References........................................111