Signaling System 7 (SS7) Message Transfer Part 2 (MTP2) - User Peer-to-Peer Adaptation Layer (M2PA)
RFC 4165

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Network Working Group                                       T. George
Request for Comments: 4165                                B. Bidulock
Category: Standards Track                                     OpenSS7
                                                             R. Dantu
                                            University of North Texas
                                                      H. Schwarzbauer
                                                              Siemens
                                                         K. Morneault
                                                        Cisco Systems
                                                       September 2005

       Signaling System 7 (SS7) Message Transfer Part 2 (MTP2) -
               User Peer-to-Peer Adaptation Layer (M2PA)

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 (2005).

Abstract

   This document defines a protocol supporting the transport of
   Signaling System Number 7 (SS7) Message Transfer Part (MTP) Level 3
   signaling messages over Internet Protocol (IP) using the services of
   the Stream Control Transmission Protocol (SCTP).  This protocol would
   be used between SS7 Signaling Points using the MTP Level 3 protocol.
   The SS7 Signaling Points may also use standard SS7 links using the
   SS7 MTP Level 2 to provide transport of MTP Level 3 signaling
   messages.  The protocol operates in a manner similar to MTP Level 2
   so as to provide peer-to-peer communication between SS7 endpoints.

George, et al.              Standards Track                     [Page 1]
RFC 4165      SS7 MTP2-User Peer-to-Peer Adaptation Layer September 2005

Table of Contents

   1. Introduction ....................................................3
      1.1. Scope ......................................................3
      1.2. Terminology ................................................3
      1.3. Abbreviations ..............................................4
      1.4. Conventions ................................................5
      1.5. Signaling Transport Architecture ...........................5
      1.6. Services Provided by M2PA ..................................7
      1.7. Functions Provided by M2PA .................................9
      1.8. Definition of the M2PA Boundaries .........................10
      1.9. Differences Between M2PA and M2UA .........................10
   2. Protocol Elements ..............................................12
      2.1. Common Message Header .....................................12
      2.2. M2PA Header ...............................................13
      2.3. M2PA Messages .............................................14
   3. State Control ..................................................17
      3.1. SCTP Association State Control ............................17
      3.2. M2PA Link State Control ...................................18
   4. Procedures .....................................................19
      4.1. Procedures to Support MTP2 Features .......................19
      4.2. Procedures to Support the MTP3/MTP2 Interface .............30
      4.3. SCTP Considerations .......................................33
   5. Examples of M2PA Procedures ....................................34
      5.1. Link Initialization (Alignment) ...........................34
      5.2. Message Transmission and Reception ........................37
      5.3. Link Status Indication ....................................37
      5.4. Link Status Message (Processor Outage) ....................38
      5.5. Level 2 Flow Control ......................................42
      5.6. MTP3 Signaling Link Congestion ............................44
      5.7. Link Deactivation .........................................45
      5.8. Link Changeover ...........................................45
   6. Security Considerations ........................................47
   7. IANA Considerations ............................................47
      7.1. SCTP Payload Protocol Identifier ..........................47
      7.2. M2PA Protocol Extensions ..................................48
   8. Acknowledgements ...............................................49
   9. References .....................................................50
      9.1. Normative References ......................................50
      9.2. Informative References ....................................51

George, et al.              Standards Track                     [Page 2]
RFC 4165      SS7 MTP2-User Peer-to-Peer Adaptation Layer September 2005