RE: Virtual concatenation: a clarification on sequence numbers

["Ong, Lyndon" <LyOng@ciena.com>]

Hi Juergen,

I was wondering about this, if the order of the VC-Ns is specified
twice (once by the automated path setup, and again by the
sequence number in the overhead) this could provide an additional
consistency check or it could be a source of error.  For automated
path setup, might it not be better to leave the
sequence number out of the GMPLS/ASON signaling and have it only in the
overhead?  Then there is no need for a consistency check.

Thanks,

Lyndon 

-----Original Message-----
From: Heiles Juergen [mailto:juergen.heiles@siemens.com]
Sent: Wednesday, November 06, 2002 8:41 AM
To: 'gopi@india.tejasnetworks.com'; ccamp@ops.ietf.org
Cc: sjtrowbridge@lucent.com; Bernstein, Greg; Anup@jasminenetworks.com;
mvissers@lucent.com
Subject: AW: Virtual concatenation: a clarification on sequence numbers


Gopi,

the sequence number always reflects the order of the VC-Ns within a virtual
concatenation and is never provisioned directly. In a SDH/SONET environment
with TMN provisioning and without LCAS the order is set by the TMN at the
source and sink. If the sink receives sequence numbers in the wrong order it
will alarm. With LCAS the order can change dynamical for example if one VC
fails and is removed from the group and later on added again. In case of
automatic path setup (GMPLS/ASON) this process has to define the order of
the VCs and as such the sequence numbers.


Regards

Juergen


> -----Ursprüngliche Nachricht-----
> Von: gopi@india.tejasnetworks.com 
> [mailto:gopi@india.tejasnetworks.com]
> Gesendet: Mittwoch, 6. November 2002 14:58
> An: ccamp@ops.ietf.org
> Cc: sjtrowbridge@lucent.com; GregB@ciena.com; 
> Anup@jasminenetworks.com;
> mvissers@lucent.com
> Betreff: Virtual concatenation: a clarification on sequence numbers
> 
> 
> [ post by non-subscriber.  with the massive amount of spam, 
> it is easy to
>   miss and therefore delete mis-posts.  so fix subscription 
> addresses! ]
> 
> 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
> 
> 
> 
>