RE: GMPLS issues (was - GMPLS Last Calls)

[John Drake <jdrake@calient.net>]

Niel,

I think that the point that Eric was trying to make is that the IETF isn't
the correct venue
for a PNNI based solution, although a PNNI based solution might be a
perfectly fine thing.

>From a technical perspective, unless things have changed in the past several
years, the issues
with using PNNI are its lack of support for pre-emption/priority and make
before break, and that
its bandwidth advertisements are tightly coupled to ATM service categories.

Thanks,

John

-----Original Message-----
From: neil.2.harrison@bt.com [mailto:neil.2.harrison@bt.com]
Sent: Wednesday, June 13, 2001 6:09 AM
To: Eric.Mannie@ebone.com; ananth.nagarajan@mail.sprint.com;
BRaja@tellium.com
Cc: wesam.alanqar@mail.sprint.com; ccamp@ops.ietf.org;
Tammy.Ferris@mail.sprint.com; mark.jones@mail.sprint.com; mpls@UU.NET;
lynn.neir@mail.sprint.com; andy.bd.reid@bt.com; alan.mcguire@bt.com
Subject: RE: GMPLS issues (was - GMPLS Last Calls)


> Where is the issue ? Why do we need NSAP addresses in GMPLS ?
> 
> Kind regards,
> 
> Eric
>
Eric, I understand your points on the 'management network'......that is, the
addressing of it's user-plane is a separate network to the user-plane
offered for cutsomer connections.  So let me concentrate on the 'external'
user-plane here in an attempt to answer your question.

Seems we have some choices in GMPLS at the moment:
Addressing - v4 or v6
Signalling - RSVP or CR-LDP
Routing - OSPF or IS-IS (but exterior is BGP only)

All these facets are, in principle, independent choices.  And, in
particular, since 'server layer trails = client layer links' then addressing
cannot be from the same space at a server and client layer.  The addressing
might have exactly the same format, but it comes from a different space, ie
address X at layer M is not = address X at layer M.

Given that the layers have to be decoupled in the general case (for
commercial as well as technical reasons - see the BT 'Freeland' requirements
draft to 12/00 mtg) then there seems to be no reason why an operator could
not use NSAPs for the access points of SDH or OTNs if he so wished.  And,
given this choice, that operator might also prefer to use PNNI as the
signalling/routing solution too.  So, the issue seems not one of
'necesssity' but simply choice......though there may be certain technical
benefits of choosing 1 solution over another.  I don't believe there is
anything technically wrong with saying this and giving operators/vendors a
choice here is there?.....if there is please point out the problems.

regards, Neil