Re: More route flaps & inconsistent origins

["Mark S. Fedor" <]

> > To: bgpd@localhost, routing-wg@localhost
> > Subject: Re: More route flaps & inconsistent origins
> > Date: Thu, 13 Oct 1994 22:58:15 +0100
> > From: Havard Eidnes <Havard.Eidnes@localhost
> > 
> > Hi,
> > 
> > again, here is a new route flap report.  The villains from the
> > top of the previous report have apparently fixed their problem,
> > but a few ASes again manage to get the dubious position at the
> > top of the list with more than 20.000 route flaps in the 24 hours
> > from Oct 12 03:05 GMT to Oct 13 03:05 GMT.
> > 
> > Again I would like to draw to your attention the fact that some
> > destinations are apparently being originated by more than one AS.
> > These show up in the report with more then one origin.  I was
> > under the impression that thsi is an illegal or highly
> > undesireable configuration; I would still like to hear some
> > comments on this issue.
> 
> This is not illegal by the BGP RFC, but it is basicly frowned upon by
> operators and the BGPd community.  This usually occurs when people are
> back-leaking redistributing IGP's into different BGP ASs.
> 

If you were homed to the NSFNET in two different places, you needed
unique AS's at each peering point.  So you had to dump your nets
into two different AS's.  I realize this recently changed,
but why deal with it now, when it will soon go away.

mf

> By the way, an interesting statistic here is not so much the originating
> AS (yes, that is interesting, but...) but rather determining transit ASs
> that are causing the flaps.
> 
> For instance, say AS 109 is transited by AS 200, and AS 200 flaps a lot.
> AS 109 will show up as flapping and the flaps aren't debited against 200,
> so you don't discover the real problem.
> 
> Paul
> 
> * AS's used in this are only for example purposes, no slam against barrnet
>   intended. :-)