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