draft-ietf-sigtran-m2pa-03.txt

No7信令,我需要交换类似的代码, 请店长审核,谢谢了,急着交换,谢谢

Network Working Group                                      Tom George
INTERNET-DRAFT                                                Alcatel
                                                            Ram Dantu
                                                        Cisco Systems
                                                      Malleswar Kalla
                                                            Telcordia
                                           Hanns Juergen Schwarzbauer
                                                              Siemens
                                                      Greg Sidebottom
                                                        Ken Morneault
                                                        Cisco Systems

                                                              
Expires January 2002                                    July 20, 2001


             SS7 MTP2-User Peer-to-Peer Adaptation Layer
                  <draft-ietf-sigtran-m2pa-03.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. 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.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as 'work in progress.'

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.

To learn the current status of any Internet-Draft, please check the
'1id-abstracts.txt' listing contained in the Internet-Drafts Shadow
Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or
ftp.isi.edu (US West Coast).













George, et al                                                 [Page 1]

Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  July 2001


Abstract

This Internet Draft defines a protocol supporting the transport of
Signaling System Number 7 (SS7) Message Transfer Part (MTP) Layer 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 employing the MTP Level 3
protocol. The SS7 Signaling Points may also employ standard SS7 links
using the SS7 MTP Layer 2 to provide transport of MTP Layer 3
signaling messages.












































George, et al                                                 [Page 2]

Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  July 2001



                        TABLE OF CONTENTS

1.  Introduction............................................. 4
  1.1  Scope................................................. 4
  1.2  Terminology........................................... 4
  1.3  Abbreviations......................................... 5
  1.4  Conventions........................................... 6
  1.5  Signaling Transport Architecture...................... 6
  1.6  Services Provided by M2PA............................. 8
  1.7  Functions Provided by M2PA............................ 9
  1.8  Definition of the M2PA Boundaries.....................10
  1.9  Differences Between M2PA and M2UA.....................12
2.  Protocol Elements........................................14
  2.1  Common Message Header.................................14
  2.2  M2PA Messages.........................................16
3.  M2PA Link State Control..................................19
4.  Procedures...............................................22
  4.1  Procedures to Support MTP2 Features...................22
  4.2  Procedures to Support the MTP3/MTP2 Interface.........31
5.  Examples of M2PA Procedures..............................36
  5.1  Link Initialization (Alignment).......................36
  5.2  Message Transmission and Reception....................39
  5.3  Link Status Indication................................39
  5.4  Link Status Message (Processor Outage)................40
  5.5  Level 2 Flow Control..................................41
  5.6  MTP3 Signaling Link Congestion........................43
  5.7  Link Deactivation.....................................44
  5.8  Link Changeover.......................................45
6.  Security.................................................47
  6.1  Threats...............................................47
  6.2  Protecting Confidentiality............................47
7.  IANA Considerations......................................48
  7.1  SCTP Payload Protocol Identifier......................48
  7.2  M2PA Protocol Extensions..............................48
8.  Acknowledgements.........................................49
9.  References...............................................50
10. Authors' Addresses.......................................51
















George, et al                                                 [Page 3]

Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  July 2001

1. Introduction

1.1 Scope

There is a need for Switched Circuit Network (SCN) signaling protocol
delivery over an IP network.  This includes message transfer between
the following: 

   - a Signaling Gateway (SG) and a Media Gateway Controller (MGC)
     [1]

   - a SG and an IP Signaling Point (IPSP)

   - an IPSP and an IPSP

This could allow for convergence of some signaling and data
networks. SCN signaling nodes would have access to databases and other
devices in the IP network domain that do not employ SS7 signaling
links. Likewise, IP telephony applications would have access to SS7
services. There may also be operational cost and performance
advantages when traditional signaling links are replaced by IP network
"connections".

The delivery mechanism described in this document allows for full MTP3
message handling and network management capabilities between any two
SS7 nodes, communicating over an IP network. An SS7 node equipped with
an IP network connection is called an IP Signaling Point (IPSP). The
IPSPs function as traditional SS7 nodes using the IP network instead
of SS7 links.

The delivery mechanism should

   - Support seamless operation of MTP3 protocol peers over an IP
     network connection.

   - Support the MTP Level 2 / MTP Level 3 interface boundary.

   - Support management of SCTP transport associations and traffic
     instead of MTP2 Links.

   - Support asynchronous reporting of status changes to management.


1.2 Terminology

MTP - The Message Transfer Part of the SS7 protocol [2] [3].

MTP2 - MTP Level 2, the MTP signaling link layer.

MTP3 - MTP Level 3, the MTP signaling network layer.





George, et al                                                 [Page 4]

Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  July 2001

MTP2-User - A protocol that normally uses the services of MTP Level
2. The only MTP2 user is MTP3. The MTP2 user is equivalent to the M2PA
user.

Signaling End Point (SEP) - A node in an SS7 network that originates
or terminates signaling messages.  One example is a central office
switch.

IP Signaling Point (IPSP) - An SS7 Signaling Point with an IP
network connection used for SS7 over IP. 

Signaling Gateway (SG) - A signaling agent that receives/sends SCN
native signaling at the edge of the IP network [4]. In this context,
an SG is an SS7 Signaling Point that has both an IP network connection
used for SS7 over IP, and a traditional (non-IP) link to an SS7
network.

Signaling Transfer Point (STP) - A node in an SS7 network that routes
signaling messages based on their destination point code in the SS7
network.

Association - An association refers to a SCTP association [5]. The
association provides the transport for MTP3 protocol data units and
M2PA adaptation layer peer messages.

Network Byte Order - Most significant byte first, also known as "Big
Endian". See [15], Appendix B Data Transmission Order.

Stream - A stream refers to a SCTP stream [5].  


1.3 Abbreviations

BSNT   - Backward Sequence Number to be Transmitted

FSNC   - Forward Sequence Number of last message accepted by 
         remote level 2

LI     - Length Indicator

MSU    - Message Signal Unit

SCCP   - Signaling Connection Control Part

SCN    - Switched Circuit Network

SCTP   - Stream Control Transmission Protocol

SIF    - Signaling Information Field

SIO    - Service Information Octet

SLC    - Signaling Link Code


George, et al                                                 [Page 5]

Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  July 2001

SS7    - Signaling System Number 7

SSN    - Stream Sequence Number

STP    - Signal Transfer Point


1.4 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
[8].


1.5 Signaling Transport Architecture

The architecture that has been defined [4] for Switched Circuit
Network (SCN) signaling transport over IP uses multiple components,
including an IP transport protocol, the Stream Control Transmission
Protocol (SCTP), and an adaptation module to support the services
expected by a particular SCN signaling protocol from its underlying
protocol layer.

Within this framework architecture, this document defines an SCN
adaptation module that is suitable for the transport of SS7 MTP3
messages.

Figure 1 shows the seamless interworking at the MTP3 layer.  MTP3 is
adapted to the SCTP layer using the MTP2 User Peer-to-peer Adaptation
Layer (M2PA).  All the primitives between MTP3 and MTP2 are supported
by M2PA.  The SCTP association acts as one SS7 link between the IPSPs.
An IPSP may have the Signaling Connection Control Part (SCCP) and
other SS7 layers above MTP3.





















George, et al                                                 [Page 6]

Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  July 2001


            ********   IP   ********
            * IPSP *--------* IPSP *
            ********        ********

            +------+        +------+
            | TCAP |        | TCAP |
            +------+        +------+
            | SCCP |        | SCCP |
            +------+        +------+
            | MTP3 |        | MTP3 | 
            +------+        +------+    
            | M2PA |        | M2PA |    
            +------+        +------+    
            | SCTP |        | SCTP | 
            +------+        +------+
            | IP   |        | IP   |
            +------+        +------+

    IP    - Internet Protocol
    IPSP  - IP Signaling Point
    SCTP  - Stream Control Transmission Protocol
            (see Reference [5])

         Figure 1:  M2PA Symmetrical Peer-to-Peer Architecture