What's with all the long aspaths?

Philip Smith pfs at cisco.com
Thu Oct 23 11:01:33 CDT 2008


Jon Lewis said the following on 23/10/08 12:39:
> Is there something silly going around?  I doubt I'm the only one
> noticing these being triggered by our generous maxas-limit setting.
> 
> Oct  9 23:01:46: %BGP-6-ASPATH: ... 27754 27754 27754 ...
> Oct 17 11:10:40: %BGP-6-ASPATH: ... 43413 43413 43413 ...
> Oct 22 06:34:09: %BGP-6-ASPATH: ... 38230 38230 38230 ...
> 
> Anyone have theories as to what these networks are trying to accomplish?

Theories include:

- trying to make a /20 announcement more important than a component /24
by prepending the /24 out of sight (i'm not joking, some people really
believe this!!)

- trying to over-ride policy that their upstream provider has applied
(e.g. my prepended /20 is a backup to my main /20 announcement but my
upstream on the backup path is local pref-ing high to make them look
more "peerable")

There are bound to be other reasons... :-)

philip
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