[j-nsp] Fwd: GEANT implementing "BGP Guard Time" on their Junipers

[Hank Nussbacher]

This originally appeared on the routing-wg at ripe.net mailing list.  I'd be 
curious to hear what Juniper has to say about it.

-Hank


>     Dear all,
>
>     remembering the thread on "Route update stats" in December ?
>
>     Specifically:
>
>http://www.ripe.net/ripe/mail-archives/routing-wg/2002/msg00050.html
>
>     Now Christophe Belmont, GEANT-NOC, together with Juniper found a
>     solution and we successfully tested it:
>
>     They implemented "BGP Guard Time" (Cisco like 30 seconds) and the
>     result was impressive:
>
>     The number of BGP update messages received from GEANT dropped by ~85%
>     and the number of "flaps" seen from GEANT by ~75% !
>
>     BGP guard time (30sec) means that updates are only sent to neighbors for
>     prefixes which have stayed in the routing table for 30 seconds.  I'm
>     sure you know the specific problem, that when a prefix is withdrawn in a
>     meshed environment, lots of updates are sent from BGP entities which do
>     think that they still have a (longer) path.  It may take quite some time
>     until all these false updates are dying down.  Without this guard time a
>     BGP speaker immediately forwards all those false updates to all peers.
>     I guess that if you would globally disable BGP guard time (which
>     fortunately is default ON=30seconds for Ciscos but apparently not for
>     Junipers) quite some routers would collapse on these withdrawal
>     aftermaths.
>
>     So my suggestion would be for all ISPs using Juniper routers: turn on
>     "BGP Guard Time" (Cisco like 30 seconds).
>
>     Christophe, probably you can post the details to the list !?
>
>     Kind regards
>     CP
>
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