RE: GMPLS signaling documents updated per last calls

["Mannie, Eric" <Eric.Mannie@ebone.com>]

Hi Jonathan,

> Why SHOULD and not MUST?  This ambiguity is likely to create
interoperability problems in the future...

To leave to the manufacturer and to the user the right to decide if he/she
wants to signal an LSP as either SDH or SONET. There is no interoperability
problem at all since you use EITHER SDH OR SONET. If you decide to request
an SDH signal with what do you want to have interoperability issue at this
stage ? The sentence means indeed "one should better use SDH than SONET" !
Once you decided, there is no issue.

> I'm curious what sort of backward compatability is necessary, as a
"standard" doesn't exist currently that this needs to be backward
compatible with...

Backward compatibility with the OIF UNI 1.0 Implementation Agreement, with
the implementations that could not care of SDH, with implementations that
still do a distinction between SONET and SDH for some reasons, with the
implementations that could still use the VT3 (DS1C) (I don't have
confirmation that nobody is using it today, and this is not the goal of this
draft to state what is obsolete or not in SONET), etc.

Anyway, there is no issue, the SONET label format is not used until SONET is
explicitly requested as such. This is not a primary feature of the draft,
but a *secondary feature*, for SONET lovers. Otherwise, SDH is used for
everything, consequently you don't care of the SONET label, you skip it in
the draft, you ignore it, you don't implement it and you just use a full SDH
implementation.

I think that the solution is quite simple: if the SONET signal is indeed an
SDH signal, why do you bother with SONET ? Just ask for an SDH signal,
that's all.

By the way, since according to some folks SONET is just a subset of SDH, why
do we care about SONET in these documents ? Why don't we simply remove all
references to SONET ?

Is there somebody on this mailing list that cares about SONET ? If yes, why
? Who is still manufacturing SONET boxes ? Why is that not called SDH ?

Kind regards,

Eric

-----Original Message-----
From: Jonathan Sadler [mailto:jonathan.sadler@tellabs.com]
Sent: Tuesday, December 18, 2001 9:57 PM
To: Mannie, Eric
Cc: 'Stephen Trowbridge'; Kireeti Kompella; ccamp@ops.ietf.org;
dbrungard@att.com; lberger@movaz.com
Subject: Re: GMPLS signaling documents updated per last calls


Eric -

Comments inline...

Jonathan Sadler

"Mannie, Eric" wrote:
> "A SONET signal which has an identical SDH signal SHOULD be requested
using
> the same traffic parameters as for the equivalent SDH signal, and will
> consequently use the SDH label."

Why SHOULD and not MUST?  This ambiguity is likely to create
interoperability problems in the future...

> We spend with Maarten a lot of time to write that sentence (not easy to
> write).
> 
> Maybe that it should be better written:
> 
> "A SONET signal which has an identical SDH signal SHOULD be requested as
an
> SDH signal using the same traffic parameters as for the equivalent SDH
> signal, and will consequently use the SDH label."

Again, "SHOULD" needs to be replaced with "MUST"...

> This doesn't mean that the SONET signal format disappear (simply not used
in
> that case), for backward compatibility we need to keep it.

I'm curious what sort of backward compatability is necessary, as a
"standard" doesn't exist currently that this needs to be backward
compatible with...

> Kind regards,
> 
> Eric
> 
> -----Original Message-----
> From: Stephen Trowbridge [mailto:sjtrowbridge@lucent.com]
> Sent: Tuesday, December 18, 2001 7:46 PM
> To: Kireeti Kompella
> Cc: ccamp@ops.ietf.org; dbrungard@att.com; lberger@movaz.com;
> bwijnen@lucent.com; sob@harvard.edu
> Subject: Re: GMPLS signaling documents updated per last calls
> 
> Kireeti,
> The one outlyer is VT3 (3 Megabits). VC-3 is an extremely popular
> rate in both SONET and SDH. I exchanged an email with Deborah Brungard
> (T1X1.5 chair) on this one and I take the liberty of sharing her response:
> 
> Deborah Brungard wrote:
> > The VT3 (3M) structure was defined - but no services (mappings) were
ever
> defined for it. So there are no services/equip
> > with it. My take was if in the future it was ever defined (doubtful), we
> would be adding it to g707 also. So then it
> > would just be part of g707 too.
> 
> So basically, there are no mappings or equipment functions for this rate,
> and as far as we know no network equipment or networks supporting it.
> Deborah suggests that if we were ever to define such mappings, that this
> would be proposed for addition to G.707 and hence be part of SDH.
> 
> I think our agreement had been to use the SDH label for all signals that
> had the same multiplex structure in SONET and SDH. In Salt Lake City, we
> thought
> that this was everything except VT3. Given that VT3 seems not to be a
"real"
> signal at this point and will likely be added to SDH if it ever becomes
> real, does our agreement then become that we use SDH labels for
everything?
> 
> Regards,
> Steve
> 
> Kireeti Kompella wrote:
> >
> > Hi Deborah,
> >
> > > I previously made the
> > > comments to merge the (1) SDH and SONET values as one value
> >
> > There was a meeting among Steve Trowbridge, Maarten Vissers,
> > Eric Mannie, Dimitri Papadimitriou, the CCAMP ADs and chairs on
> > several issues, among them this one.  The upshot was that whenever
> > possible, the SDH label should be used, with the encoding type
> > set to SDH (i.e., G.707); however, there are signals that have
> > no SDH equivalent (if I remember right, VC-3 -- someone correct
> > me!), so we will keep SONET labels and encoding types around
> > for that case and for legacy equipment.
> >
> > The revised SONET/SDH document will contain the exact wording.
> > I will also be sending a reply to the ITU communication stating
> > the agreement we came to.
> >
> > Kireeti.