The MPLS-OPS Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] Re: Head end computation of LSP
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. > > >> >> hth >> >>> >>> -Sylvia >>> >>> >>> >>> >>> >>> >> > ___________________________________________________________ALL-NEW >> >>> Yahoo! Messenger - all new features - even more >> fun! >>> http://uk.messenger.yahoo.com >>> >>> ------- >>> The MPLS-OPS Mailing List >>> Subscribe/Unsubscribe: >> http://www.mplsrc.com/mplsops.shtml >>> Archive: >> http://www.mplsrc.com/mpls-ops_archive.shtml >>> >>> >> >> -- >> Aamer Akhter / aa@cisco.com >> NSITE cisco Systems >> >> > > > > > > ___________________________________________________________ALL-NEW > Yahoo! Messenger - all new features - even more fun! > http://uk.messenger.yahoo.com > > -- Aamer Akhter / aa@cisco.com NSITE cisco Systems ------- The MPLS-OPS Mailing List Subscribe/Unsubscribe: http://www.mplsrc.com/mplsops.shtml Archive: http://www.mplsrc.com/mpls-ops_archive.shtml
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