RE: Virtual concatenation: a clarification on sequence numbers

[Steve Gorshe <Steve_Gorshe@pmc-sierra.com>]

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Dear Gopi,

We have noted that the language describing Virtual Concatenation is not 
clear some of these points.  The G.707 editor (Huub van Helvoort) and I 
are working on some revised text for G.707 and ANSI T1.105 (for which I 
am the editor) to clarify these points.  The answer to your question is 
that the sequence number is automatically assigned by the transmitting 
equipment and followed by the receiving equipment.  The LCAS protocol 
(ITU-T G.7042) for adjusting the bandwidth of a Virtually Concatenated 
channel depends on this.  

Best regards,
Steve

Steve Gorshe, Ph.D.
Principal Engineer - Product Research
PMC-Sierra, Inc.
10565 S.W. Nimbus Ave.
Portland, OR 97223
Tel: +1 503 431 7440
Fax: +1 503 431 7400
steve_gorshe@pmc-sierra.com


-----Original Message-----
From: gopi@india.tejasnetworks.com [mailto:gopi@india.tejasnetworks.com]
Sent: Wednesday, November 06, 2002 5:58 AM
To: ccamp@ops.ietf.org
Cc: sjtrowbridge@lucent.com; GregB@ciena.com; Anup@jasminenetworks.com;
mvissers@lucent.com
Subject: Virtual concatenation: a clarification on sequence numbers


hi..

I was going through the thread
        http://ops.ietf.org/lists/ccamp/ccamp.2001/threads.html#00295
        subject: "concatenation extensions in sonet/sdh"

I needed a small clarification on virtual concatenation sequencing

Sequence number is sent by the transmitter and receiver checks for
the sequence number to perform interleaving.

  IS this sequence number "Provisioned"(on both terminating equipments) ?
   OR
  Is it automatically assigned by the transmitting equipment in some
  sequence and the receiver synchronizes with the transmitters sequence number?


I read the following relevant standards on virtual concatenation, but couldn't
clearly understand how the receiver knows the sequencing of the
individual links.
+ T1X1.5/2001-062(Synchronous Optical Network (SONET) - Basic
    Description including Multiplex Structure, Rates and Formats,
    put up on ftp.t1.org/..../1X150620.DOC)
+ G.707, G.783(virtual concatenation)
+ G.7042(LCAS)

Thanx in advance
Gopi