The MPLS WG Archive

[Heiles Juergen <Juergen.Heiles@icn.siemens.de>]

Neil,

I think this is a fundamental question we have to anwser:
Is the LSP always identical to a trail in the transport plane?
In my view not necessarly. The LSP could also be a sub-network connection.
Consider in the future a VC-4 trail crossing several operator domains. Some operators can automatically set-up the VC--4 path through their network using GMPLS. Other operators still use todays method with path-setup via the TMN. The operator with GMPLS sets-up a SPC for this VC-4 (and not any server layer) through its network. The set-up request for this LSP comes from the TMN and not via a UNI/NNI as the other operator or the user at the end-point doesn't support it. In this case the LSP spans only a part/sub-network connection of the overall VC-4 trail.
I might be also only a definition problem. What is a LSP, the overall connection through the network or only the part that is set-up using GMPLS signaling?

Juergen

> -----Original Message-----
> From:	neil.2.harrison@bt.com [SMTP:neil.2.harrison@bt.com]
> Sent:	Wednesday, December 06, 2000 11:07 PM
> To:	Juergen.Heiles@icn.siemens.de; jdrake@calient.net; mpls@UU.NET
> Cc:	ip-optical@lists.bell-labs.com
> Subject:	RE: [IP-Optical] GMPLS - Hierarchies
> 
> <snipped>
> 
> > Furthermore a LSP -at least for circuit switching - doesn't have to start
> > and end at the trail termination where you extract your payload.
> 	NH=> I fudamentally disagree *if* we are adhering to functional
> arch. 
> >  A LSP could be used only for a sub part of the overall connection, e.g. a
> > DS1 signal starts in a user domain with tradional TMN path setup or even
> > manual connections, the DS1 comes to a operator which uses GMPLS for path
> > -setup (in this case a permanent connection set-up by himself as the user
> > doesn't support the UNI). The LSP starts in the middleof the overall DS1
> > connection and no access to the paylaod of the DS1 is requried at that
> > point.
> 	NH=> The DSI signal is 'an LSP' in its own right......it is, after
> all, a clear layer network trail entity.  The fact that it may be served (on
> link connections, which are a partition of the end-end DS1 trail) by lower
> layer "LSPs" (which could be a DS3, VC4, ODU, etc.......and which themselves
> are trails *but* only between their points of source/sink) is
> academic.....the DS1 trail is completely unaware of this, and the layering
> recursion of client_links=>server_trails can recurse many times.......its
> stops at the duct network.
> 	Your example *must*, and indeed does, fit this. 
> 	neil 
> 
> >