Signaling System 7 (SS7) Message Transfer Part 3 (MTP3) - User Adaptation Layer (M3UA)
RFC 4666

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Network Working Group                                  K. Morneault, Ed.
Request for Comments: 4666                                 Cisco Systems
Obsoletes: 3332                                    J. Pastor-Balbas, Ed.
Category: Standards Track                                       Ericsson
                                                          September 2006

       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 (2006).

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.  This document obsoletes
   RFC 3332.

Morneault & Pastor-Balbas   Standards Track                     [Page 1]
RFC 4666             SS7 MTP3-User Adaptation Layer       September 2006

Table of Contents

   1. Introduction ....................................................6
      1.1. Scope ......................................................6
      1.2. Terminology ................................................6
      1.3. M3UA Overview ..............................................9
           1.3.1. Protocol Architecture ...............................9
           1.3.2. Services Provided by the M3UA Layer ................10
                  1.3.2.1. Support for the Transport of
                           MTP3-User Messages ........................10
                  1.3.2.2. Native Management Functions ...............11
                  1.3.2.3. Interworking with MTP3 Network
                           Management Functions ......................11
                  1.3.2.4. Support for the Management of SCTP
                           Associations between the ..................11
                  1.3.2.5. Support for the Management of
                           Connections to Multiple SGPs ..............12
      1.4. Functional Areas ..........................................12
           1.4.1. Signalling Point Code Representation ...............12
           1.4.2. Routing Contexts and Routing Keys ..................14
                  1.4.2.1. Overview ..................................14
                  1.4.2.2. Routing Key Limitations ...................15
                  1.4.2.3. Managing Routing Contexts and
                           Routing Keys ..............................15
                  1.4.2.4. Message Distribution at the SGP ...........15
                  1.4.2.5. Message Distribution at the ASP ...........16
           1.4.3. SS7 and M3UA Interworking ..........................16
                  1.4.3.1. Signalling Gateway SS7 Layers .............16
                  1.4.3.2. SS7 and M3UA Interworking at the SG .......17
                  1.4.3.3. Application Server ........................17
                  1.4.3.4. IPSP Considerations .......................18
           1.4.4. Redundancy Models ..................................18
                  1.4.4.1. Application Server Redundancy .............18
           1.4.5. Flow Control .......................................18
           1.4.6. Congestion Management ..............................19
           1.4.7. SCTP Stream Mapping ................................19
           1.4.8. SCTP Client/Server Model ...........................19
      1.5. Sample Configuration ......................................20
           1.5.1. Example 1: ISUP Message Transport ..................20
           1.5.2. Example 2: SCCP Transport between IPSPs ............21
           1.5.3. Example 3: SGP Resident SCCP Layer, with
                  Remote ASP .........................................22
      1.6. Definition of M3UA Boundaries .............................23
           1.6.1. Definition of the Boundary between M3UA and
                  an MTP3-User .......................................23
           1.6.2. Definition of the Boundary between M3UA and SCTP ...23
           1.6.3. Definition of the Boundary between M3UA and
                  Layer Management ...................................24