draft-george-sigtran-m2peer-01.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

Even though the SCTP association is established, it is important that
M2UA not send MTP3 data at this point. It must be confirmed that both
ends of the link are ready for traffic. Otherwise, messages could be
lost. Therefore proving begins at this time:


    MTP3        M2UA        SCTP        SCTP        M2UA        MTP3
    ----        ----        ----        ----        ----        ----

                 Link Status In Alignment
                 ------------------------------------>
                 ------------------------------------>
                 ------------------------------------>
                 :
                 ------------------------------------>

                 Link Status In Alignment messages are  
                   sent for period T4.

                 Status
                 ------------>

                 Link Status In Service
                 ------------------------------------>

                                Link Status In Service
                 <------------------------------------

     In Service
     <------------


At this point, MTP3 may begin sending data messages.





















George, et al                                               [Page 17]


Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  May 2000

4.2  Message Transmission and Reception

Messages are transmitted using the Data Request primitive from MTP3 to
M2UA. The diagram shows the case where the Link is In Service. The
message is passed from MTP3 of the source to MTP3 of the destination.


    MTP3        M2UA        SCTP        SCTP        M2UA        MTP3
    ----        ----        ----        ----        ----        ----

     Message for 
     transmission
     ------------>

                 Send
                 (Data Message)
                 ------------>

                             (SCTP sends message)

                                         Receive
                                         ------------>

                                                  Received message
                                                     ------------>


4.3  Link Status Indication

If SCTP sends a Communication Lost primitive to M2UA, M2UA notifies
MTP3 that the link is out of service. MTP3 responds in its usual way.


    MTP3        M2UA        SCTP        SCTP        M2UA        MTP3
    ----        ----        ----        ----        ----        ----

                 Communication Lost
                 <------------

     Out of Service
     <------------













George, et al                                               [Page 18]


Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  May 2000

4.4  Link Status Message (Processor Outage)

This example shows how M2UA responds to a local processor outage. M2UA
sends a Link Status message to its peer. The peer M2UA notifies MTP3
of the outage. MTP3 can then follow the processor outage procedures in
[2].


    MTP3        M2UA        SCTP        SCTP        M2UA        MTP3
    ----        ----        ----        ----        ----        ----

             M2UA detects 
             Local Processor 
             Outage

                 Link Status
                 ------------>

                             (SCTP sends message)

                                         Receive
                                         ------------>

                                                  Remote Processor
                                                  Outage
                                                     ------------>




























George, et al                                               [Page 19]


Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  May 2000

4.5  Congestion Notification to Upper layer

MTP3 layer expects notification of the link congestion.  For example,
this is accomplished by two messages 1) Link Congestion Onset 2) Link
Congestion Abated.  Congestion is assumed if M2UA layer notices
repeated failures to send requests to SCTP (this is implementation
dependent and it is assumed that the SEND Failure has an error code
"life time expired").  Subsequently M2UA can start polling status of
SCTP.  If all the messages are successfully transmitted over a period
of time (implementation dependent) then it is assumed that the
congestion is abated.  If the congestion condition should continue,
the link will be taken out of service.  In this case, it is possible
to start the link changeover procedure.

The US National version of SS7 has congestion levels. For US National
SS7, the Indication primitive for Congestion Onset should report the
congestion level.

In the example below, M2UA has sent a message to SCTP.


    MTP3        M2UA        SCTP        SCTP        M2UA        MTP3
    ----        ----        ----        ----        ----        ----

                 Implementation dependent 
                 indication of congestion 
                 <------------

     Congestion Onset
     <------------

                 Status
                 ------------>
                 Status
                 ------------>
                 :
                 :
                 Status
                 ------------>
                 polled for certain time until
                 congestion ceases -
                 implementation dependent

     Congestion Abatement
     <------------









George, et al                                               [Page 20]


Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  May 2000


4.6  Link Deactivation

The MTP3 can request that a SS7-IP link be taken out-of-service.  It
uses the Release Request message as shown below.


    MTP3        M2UA        SCTP        SCTP        M2UA        MTP3
    ----        ----        ----        ----        ----        ----

     Stop
     ------------>

                 Terminate
                 ------------>

                           (SCTP performs its
                           termination procedure)

                 Communication Lost
                 <------------

     Out of Service
     <------------



4.7  Link Changeover

In this example, MTP3 performs a changeover because the link went out
of service. MTP3 selects a different link for retransmitting the
unacknowledged messages.

Note that the sequence numbers and messages requested by MTP3 are sent
from SCTP to M2UA in the Communication Lost primitive.



















George, et al                                               [Page 21]


Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  May 2000


    MTP3        M2UA        SCTP        SCTP        M2UA        MTP3
    ----        ----        ----        ----        ----        ----

                 Communication Lost
                 <------------

     Out of Service
     <------------

     Retrieve BSN
     ------------>

                 (M2UA locates
                  first gap in
                  received messages)

     Indicate BSN
     <------------


     XCO (BSN) on another link
     ------------------------------------------------------------>

                                                      Retrieve BSN
                                                     <------------

                                                      Indicate BSN
                                                     ------------>

                                                         XCA (BSN)
     <------------------------------------------------------------

     Retrieve FSN
     ------------>

                 (M2UA locates
                  first gap in
                  acknowledgements)

     Retrieved Message
     <------------
     
     Retrieved Message
     <------------

     Retrieval Complete
     <------------

     Send messages on another link.




George, et al                                               [Page 22]


Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  May 2000

5. Security

SCN adaptation layers rely on SCTP to provide security.
 

6.  IANA Considerations

The SCTP (and UDP/TCP) Registered User Port Number Assignment for M2UA
is TBD.

The value assigned by IANA for the Payload Protocol Identifier in the
SCTP Payload Data chunk is 

        M2UA Peer    TBD

The SCTP Payload Protocol Identifier is included in each SCTP Data
chunk, to indicate which protocol the SCTP is carrying. This Payload
Protocol Identifier is not directly used by SCTP but may be used by
certain network entities to identify the type of information being
carried in a Data chunk.

The User Adaptation peer may use the Payload Protocol Identifier as a
way of determining additional information about the data being
presented to it by SCTP.

7.  Acknowledgements

The authors would like to thank Ian Rytina for his valuable comments
and suggestions.

8.  References

[1] ITU-T Recommendation Q.700, 'Introduction To ITU-T Signalling 
    System No. 7 (SS7)'

[2] ITU-T Recommendation Q.701-Q.705, 'Signalling System No. 7 
    (SS7) - Message Transfer Part (MTP)'

[3] Bellcore GR-246-CORE 'Bell Communications Research Specification
    of Signaling System Number 7', Volume 1, December 1995

[4] RFC 2719, Framework Architecture for Signaling Transport, 
    October 1999

[5] Stream Control Transmission Protocol,
    draft-ietf-sigtran-sctp-09.txt, April 19, 2000

[6] SS7 MTP2-User Adaptation Layer, draft-ietf-sigtran-m2ua-00.txt, 
    March 2000

[7] ITU-T Recommendation Q.2210, 'Message transfer part level 3
    functions and messages using the services of ITU-T 
    Recommendation Q.2140'

George, et al                                               [Page 23]


Internet Draft  SS7 MTP2-User Peer-to-Peer Adaptation Layer  May 2000


9.  Author's Addresses

Tom George                                        Tel: [phone]
Alcatel USA                          EMail: [e-mail]
1000 Coit Road          
Plano, TX 75075    
USA

Ram Dantu, Ph.D.                    Tel: [phone] extension 211
IPmobile                                    EMail: [e-mail]
1651 North Glenville, Suite 216
Richardson, TX 75081
USA

Malleswar Kalla                                   Tel: [phone]
Telcordia Technologies             EMail: [e-mail]
MCC 1J211R
445 South Street
Morristown, NJ 07960
USA

Hanns Juergen Schwarzbauer                       Tel: [phone]
SIEMENS AG                    [e-mail]
Hofmannstr. 51
81359 Munich
Germany

Greg Sidebottom                                   Tel: [phone]
Nortel Networks                     EMail: [e-mail]
3685 Richmond Rd,
Nepean, Ontario 
Canada  K2H5B7

Ken Morneault                                     Tel: [phone]
Cisco Systems Inc.                           EMail: [e-mail]
13615 Dulles Technology Drive
Herndon, VA. 20171
USA


This Internet Draft expires November 2000.












George, et al                                               [Page 24]