Long AS Path
pf at tippete.net
Thu Jun 22 06:09:41 CST 2017
>>>>> "Mel" == Mel Beckman <mel at beckman.org> writes:
Mel> Why not ask the operator why they are pretending this path? Perhaps
Mel> they have a good explanation that you haven't thought of. Blindly
Mel> limiting otherwise legal path lengths is not a defensible practice, in
Mel> my opinion.
Mel> -mel beckman
A prepend like that is usually the result of someone using the IOS
syntax on a XR or Junos router.
Long ago, someone accidentally prepending 255 times hit a bug (or was it
a too strict bgp implementation? I don't remember) resulting in several
networks across the globe dropping neighbors. One has to protect against
these things somehow.
As a data point, here is how many prefixes I see on my network for each
as-path length, after removing prepends:
aspath length count
So, does your customer have a legitimate reason to prepend more than 5
times? Maybe. I still think that anyone that does should have their BGP
driving licence revoked, though.
Pierfrancesco Caci, ik5pvx
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