Did your BGP crash today?

Paul Ferguson fergdawgster at gmail.com
Sun Aug 29 02:30:21 CDT 2010


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On Sun, Aug 29, 2010 at 12:23 AM, Mikael Abrahamsson <swmike at swm.pp.se>
wrote:

> On Sat, 28 Aug 2010, Brett Frankenberger wrote:
>
>> The implementor is to blame becuase the code he wrote send out BGP
>> messages which were not properly formed.
>
> People talk about not dropping sessions but instead dropping malformed
> messages. This is not safe. We've seen ISIS (which is TLV based and *can*
> drop individual messages) been wrongly implemented and platforms drop the
> entire ISIS *packet* instead of the individual message when seeing
> something malformed (or rather in this case, ISIS multi topology which
> the
> implementation didn't understand), and this made the link state database
> go out of sync and miss information for things it actually should have
> understood.
>
> This was *silent* error/corruption. I'm not sure I prefer to have silent
> problems instead of tearing down the session which is definitely
> noticable.
>

It would seem to me that there should actually be a better option, e.g.
recognizing the malformed update, and simply discarding it (and sending the
originator an error message) instead of resetting the session.

Resetting of BGP sessions should only be done in the most dire of
circumstances, to avoid a widespread instability incident.

- - ferg

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-- 
"Fergie", a.k.a. Paul Ferguson
 Engineering Architecture for the Internet
 fergdawgster(at)gmail.com
 ferg's tech blog: http://fergdawg.blogspot.com/




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