Long AS Path

James Bensley jwbensley at gmail.com
Sat Jun 24 07:41:54 CST 2017

On 23 Jun 2017 17:03, "Mel Beckman" <mel at beckman.org> wrote:


The question is whether you would actually hear of any problems. Chances
are that the problem would be experienced by somebody else, who has no idea
that your filtering was causing it.

 -mel beckman

Hi Mel,

For us this the answer is almost definitely a yes. We are an MSP (managed
service provider) as opportunities to a traditional ISP, so our customers
know they can open a ticket with us for pretty much anything and we'll try
and look into it.

We have had some weird issues with far away sites, first line can't find
any issue, it works it's way up to somebody who knows how to check if we
would be filtering a route on our transit and peering sessions.

Earlier when I said that care is required when filtering long AS_PATH
routes or certain AS numbers, we looked at the BGP table to see exactly
which routes we'd drop before hand and communicated out these changes. I
think for an MSP this shouldn't be hard to implement and manage, I can
appreciate for a "flat" ISP ("he's some transit, help yourself") it could
be more challenging.

In relation to the OPs question, long AS_PATH routes can be filtered I just
wouldn't bother except for very long paths to drop as little as possible
and be sure of whY you drop/filter.


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