Re: Virtual concatenation: a clarification on sequence numbers

[Maarten Vissers <mvissers@lucent.com>]

Gopi,

As you will have noticed from the figures I emailed yesterday, there is a
possibility to end up with the wrong sequence order (e.g. incorrect path setup
or faulty selector circuit). In such case dSQM will identify this and when
persistent (fSQM) it will initiate corrective actions.

Regards,

Maarten

gopi@india.tejasnetworks.com wrote:
> 
> Dear Steve,
> 
>   This leads me to another doubt.  What is the use of dSQM when
> there is no expected sequence number? What is the mismatch?  Or is
> the dSQM modified to mean something like "If 3-5 consecutive received
> sequence numbers on a link are not the same, dSQM is declared" ?
> 
> Is it possible for you to send a copy of the revised text which
> clarifies these points?
> 
> From all the mails that I've received on this topic, it seems that
> people are divided on this.  Hope the standard clarifies it without
> any ambiguity.
> 
> Greg: I was referring to the internal sequence numbers of the virtual
> concatenation and not the timeslot numbering...
> 
> thanx
> gopi
> 
> On Wed, 6 Nov 2002, Steve Gorshe wrote:
> 
> > 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
> >
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