Re: [Idr] Progressing draft-bhatia-bgp-multiple-next-hops-01.txt

["Glen Kent" <glen.kent at gmail.com>]

A quick Q while we're discussing various mechanisms to advertise multiple paths.

What is a router supposed to do if it recieves two paths from a BGP
speaker as described below?

Path 1 - NLRI 192/8 AS_PATH {10 20} LOCAL_PREF 100 NEXT_HOP 1.1.1.1

Path 2 - NLRI 192/8 AS_PATH {10 20} LOCAL_PREF 189 NEXT_HOP 1.1.1.1

What useful information can any router possibly derive from this?
Which route should it select? I see now value and would appreciate if
someone can enlighten me on this.

Another day, another time, but the same BGP speakers.

This router recieves two paths for 192/8 from the same BGP speaker.

Path 1 - NLRI 192/8 AS_PATH {10 20} NEXT_HOP 1.1.1.1

Path 2 - NLRI 192/8 AS_PATH {30 20} NEXT_HOP 1.1.1.1

How does this router determine which route is being used by the
upstream? I dont think we should progress any proposal without
incorporating ways to indicate which path is being actually used in
the forwarding.

I know one of the authors of multiple_hop indicated that this could be
easily done by introducing a field in the path attribute. Its not
difficult but they need to show this to us. The same goes for
add-paths.

Curtis said:

> I don't recall seeing any objections to the use of path identifier in
> draft-walton-bgp-add-paths that held up.

I think its well known that silence means lack of interest, not
acceptance. You of all the persons, should be well aware of this.

Glen

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