Re: Virtual concatenation: a clarification on sequence numbers

[Dimitri.Papadimitriou@alcatel.be]

hi,

in any case you need a number, the reason why this
has been proposed is to avoid yet another translation 
(mapping) table at the edges, these numbers must be
unique in their applicability scope, thus there will
always be a consistency check;

- dimitri.

"Ong, Lyndon" wrote:
> 
> 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
> >
> >
> >
> >

-- 
Papadimitriou Dimitri 
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