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Cell Relay Retreat>MPLS WG Archive>month:2003-Nov> msg00175



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on documenting ECMP (was on the mpls oam framework)

  • From: Curtis Villamizar <curtis@workhorse.fictitious.org>
  • Date: Tue, 18 Nov 2003 22:42:48 -0500
  • cc: "'curtis@fictitious.org'" <curtis@fictitious.org>, "'Naidu, Venkata'" <Venkata.Naidu@Marconi.com>, "'David Allan'" <dallan@nortelnetworks.com>, "'tnadeau@cisco.com'" <tnadeau@cisco.com>, mpls@UU.NET


In message <B99995113B318D44BBE87DC50092EDA90C0D5513@nj7460exch006u.ho.lucent.c
om>, "Busschbach, Peter B (Peter)" writes:
> Thanks, Curtis. You make a convincing argument.
> 
> One last question:
> 
> What happens with RSVP-TE messages at an ECMP split? Suppose a source node se
> nds a Path message requesting reservation of 10 Mb/s of bandwidth. When it re
> aches the ECMP split, will that router generate two Path messages, each reque
> sting 5 Mb/s, and forward them along the two equal-cost paths to the destinat
> ion?
> 
> Peter


Peter,

This email thread has a life of its own.  Not a comment to you but
maybe I should be appologizing for the email bandwidht I've used up.

I did try to answer that in another response.  Briefly, at a
hierarchical link you have a logical link so if you ask for 10 mb/s it
has to find 10 mb/s.  If its a bundle it finds 10 mb/s on a single
component.  If it is load spliting, it may split two ways in effect
taking 5 mb/s from each side.  Obviously it has to have 5 mb/s
available on each component LSP of the hierarchical LSP to do so.

Keep in mind that how a LSR decides how much bandwidth to allocate to
a hierarchical LSP and when to change this allocation is not defined.
[Lots of room for innovation.  The ITU guys are gonna hate it.  And
now that its been brought up we may end up spending a lot of time
explaining why it will interoperate. :) ]

Curtis