-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi All, If I'm understanding Christian correctly, he's referring to "out-delay <seconds>". This can be configured for all groups [edit protocols bgp], all neighbours in a group [edit protocols bgp group <foo>] or for an individual neighbour [edit protocols bgp group <foo> neighbour <bar>]. Regards, Guy

-----Original Message----- From: Christian Panigl, ACOnet/VIX/UniVie [mailto:panigl@cc.univie.ac.at] Sent: Tuesday, March 04, 2003 4:46 PM To: routing-wg@ripe.net Cc: christophe.belmont@c-s.fr; panigl@cc.univie.ac.at Subject: GEANT implementing "BGP Guard Time" on their Junipers (was: Route update stats)

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 I'm sure you know the specific problem, that when a prefix is withdrawn in a meshed environment, lots of updates are sent from BGP entities which do think that they still have a (longer) path.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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