router startup behavior

Jared Mauch jared at
Mon Jan 14 19:00:23 UTC 2002

On Mon, Jan 14, 2002 at 10:53:48AM -0800, Ratul Mahajan wrote:
> at university of washington, we are doing a measurement study of bgp
> misconfiguration
> (  
> one of the things we found is that there are a lot of announcements of
> more-specifics that come and go within a matter of 2-5 minutes.
> by talking to the operators involved in these incidents, we found that
> most of these are caused when the router is rebooted (intentionally or
> not). while some operators were aware of this side effect, most were not,
> and were taken by surprise that they just injected anywhere from 1-1000
> routes into BGP only to withdraw them a couple of minutes later.
> i would like to understand this behavior better. is this behavior
> vendor-specific (cisco?) or pervasive? is there a configuration style that
> causes or avoids this "spill-over"?

	It appears that routes are leaking out past a route-map
based community based on a route that you e-mailed me about (as267 /30)
that went to route-views.

> my understanding is limited to this happens when the bgp session comes up
> too soon, before the filters have taken effect. could someone familiar
> with router internals shed some light on it?
> the problem is limited to route origination only, or also propagation?  
> in other words, can a router propagate a route it should not while
> starting up because export filters are not yet in place?
> never ever gotten my hands dirty into router configuration; your input 
> would be invaluable.

	- jared

Jared Mauch  | pgp key available via finger from jared at
clue++;      |  My statements are only mine.

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