Re: Persistent BGP peer flapping - do you care?
vijay: What else causes repeative peer bounces other than the broken prefix? sue PS - I'm away from work from now until Monday morning.. At 05:42 PM 1/17/2002 -0500, Vijay Gill wrote:
On Thu, 17 Jan 2002, Dave Israel wrote:
It's a question of robustness; if the new spec includes a way to be tolerant of how the spec is (or can be) commonly abused, then the followers of the spec will not be at the mercy of those who deviate.
In this case, I think that having the option to keep a session that gives bad routes up, and just dropping the route, is a good answer. That would allow the user to determine which is preferable for a given peer: possible corruption or certain disconnection.
If you have a "bad route" how do you know the rest of the update is good? The nlri may have gotten corrupted on the wire or between the interface and the processor (parity error, or some sort of corruption on the bus). Given that case, in an update, I am not sure you can make a determination of what is good nlri and selectively propogate and process those. See also meltdowns circa nov 1998.
/vijay
### On Fri, 18 Jan 2002 21:39:10 -0500, Susan Hares <skh@nexthop.com> ### casually decided to expound upon Vijay Gill <vijay@umbc.edu> the ### following thoughts about "Re: Persistent BGP peer flapping - do you ### care? ": SH> What else causes repeative peer bounces other than the broken prefix? Well... I remember when bad capability negotiation messages would cause the session to drop. Although this is before any update messages were sent. However it still caused repeating session bouncing. -- /*===================[ Jake Khuon <khuon@NEEBU.Net> ]======================+ | Packet Plumber, Network Engineers /| / [~ [~ |) | | --------------- | | for Effective Bandwidth Utilisation / |/ [_ [_ |) |_| N E T W O R K S | +=========================================================================*/
IMO, bad negototiation messages are a bit more indicitave of a malfunctioning router that a bad prefix is, as it's unquestioningly something that was originated by the router in question, where a bad prefix could easily have originated elsewhere. Receipt of a malformed negotiation message should definitely be grounds for terminating the BGP session. Whether or not a BGP peer shuts down the peering session upon receipt of a bad prefix, it should definitely refuse to propagate the invalid data. The fact that Brand "C" routers propagated the bad prefix was the primary cause of what happened in October. -C On Fri, Jan 18, 2002 at 06:46:42PM -0800, Jake Khuon wrote:
### On Fri, 18 Jan 2002 21:39:10 -0500, Susan Hares <skh@nexthop.com> ### casually decided to expound upon Vijay Gill <vijay@umbc.edu> the ### following thoughts about "Re: Persistent BGP peer flapping - do you ### care? ":
SH> What else causes repeative peer bounces other than the broken prefix?
Well... I remember when bad capability negotiation messages would cause the session to drop. Although this is before any update messages were sent. However it still caused repeating session bouncing.
-- /*===================[ Jake Khuon <khuon@NEEBU.Net> ]======================+ | Packet Plumber, Network Engineers /| / [~ [~ |) | | --------------- | | for Effective Bandwidth Utilisation / |/ [_ [_ |) |_| N E T W O R K S | +=========================================================================*/
-- --------------------------- Christopher A. Woodfield rekoil@semihuman.com PGP Public Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xB887618B
participants (3)
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Christopher A. Woodfield -
Jake Khuon -
Susan Hares