The MPLS-OPS Archive

["Adrian Farrel" <adrian@olddog.co.uk>]

Hi,

The issue of inter-area and inter-AS traffic engineering for MPLS and GMPLS networks is
currently a work item of the CCAMP working group in the IETF. You can see some of the
related drafts on the CCAMP web page http://www.ietf.org/html.charters/ccamp-charter.html

The issues is also being considered as a key application of a possible new working group
to handle the Path Computation Element. You can read more about the PCE in
http://www.ietf.org/internet-drafts/draft-ash-pce-architecture-00.txt

Cheers,
Adrian

----- Original Message ----- 
From: "Aamer Akhter" <aakhter@cisco.com>
To: "Spice Sylvia" <falsesylvia@yahoo.co.uk>
Cc: <mpls-ops@mplsrc.com>
Sent: Tuesday, October 26, 2004 2:46 PM
Subject: Re: [MPLS-OPS]: Head end computation of LSP


>
> On Oct 26, 2004, at 1:51 AM, Spice Sylvia wrote:
>
> > Hello Aamer,
> >
> >> On Oct 25, 2004, at 1:06 AM, Spice Sylvia wrote:
> >>
> >>> Hi Aamer,
> >>>
> >>>
> >>>  --- Aamer Akhter <aakhter@cisco.com> wrote:
> >>>>
> >>>> On Oct 21, 2004, at 4:29 AM, Spice Sylvia wrote:
> >>>>
> >>>>> Hello,
> >>>>>
> >>>>> Is there a reason why the LSP setup computation
> >>>> using
> >>>>> RSVP-TE is done on the head end and not node by
> >>>> node?
> >>>>
> >>>> As RSVP-TE uses (the information) from the IGP
> >>>> topology it has the
> >>>> information it needs to compute the path (and
> >> match
> >>>> it with the best
> >>>> path request). Regardless, the path still has to
> >> be
> >>>> verified node by
> >>>> node, and the nodes still have an opportunity to
> >>>> decline the
> >>>> reservation (which triggers an igp update). It
> >>>> should be noted that
> >>>> there are way to ways (loose ero) to distribute
> >> the
> >>>> path decision at
> >>>> explicit places in the path.
> >>>
> >>>
> >>>
> >>> Say I wish to set up an LSP from A to B with the
> >>> constraint that the number of hops should be x.
> >>> Why is node by node computation not feasable in
> >> this
> >>> case?
> >>
> >> i'm not sure if the question is a theoretical one or
> >> a practical one.
> >> i'm guessing theoretical, afaik because a constraint
> >> of 'number of
> >> hops' isn't carried in the reservation
> >>
> >> unless you have something like ant routing, i don't
> >> see how you can
> >> define a constraint of hop-count and let the
> >> decision be distributed
> >> hop by hop. now if each node had a topology
> >> database, it could make
> >> that kind of decision hop-by-hop as long as the
> >> constraint was carried
> >> hop by hop as well. but if you already have a
> >> topology database, why
> >> try to do this computation hop-by-hop in the first
> >> place? the
> >> initiating node has all the information via it's
> >> instance of the
> >> topology database.
> >
> > Consider the case of an interarea or interas LSP
> > setup,
> > How exactly do people address this problem?
> >
> > I do not like to sit and write EROs for customer LSPs
> > :((
> > Is there a better method you can recommend?
> >
>
> there are several drafts that cover this area. i don't really know the
> current status though.
>
>
> > -Sylvia
> >
> >
> >
> >
> >
> > ___________________________________________________________ALL-NEW
> > Yahoo! Messenger - all new features - even more fun!
> > http://uk.messenger.yahoo.com
> >
> >
>
> -- 
> Aamer Akhter / aa@cisco.com
> NSITE cisco Systems
>
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