RE: Virtual concatenation: a clarification on sequence numbers

["Brungard, Deborah A, ALASO" <dbrungard@att.com>]

Gopi,

Just to clarify Juergen's comment, his comment is on the sequence numbers used at the VC (path layer) source and sink to align the payloads of the VCs. These sequence numbers have no relation to the timeslots used on the next level i.e. the STS-48 (OC-48 line level). For an end-to-end path over multiple connections, i.e. not physically adjacent, the timeslots used at each end will have no dependencies as they are assigned at the line layer.
Deborah

-----Original Message-----
From: Heiles Juergen [mailto:juergen.heiles@siemens.com]
Sent: Wednesday, November 06, 2002 11:41 AM
To: 'gopi@india.tejasnetworks.com'; ccamp@ops.ietf.org
Cc: sjtrowbridge@lucent.com; GregB@ciena.com; 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
> 
> 
> 
>