nanog mailing list archives
Re: Long AS Path
From: Mel Beckman <mel () beckman org>
Date: Thu, 22 Jun 2017 14:25:40 +0000
You don't have to wonder. You can call and ask them. -mel via cell
On Jun 22, 2017, at 5:47 AM, jim deleskie <deleskie () gmail com> wrote: I see 5+ prepends as maybe not reason to have your "BGP driving license revoked" but if I can continue with the concept that you have your BGP learners permit. If I think back to when I learned to code or when making ACL's, we still used line number and practice would be to give ourselves lots of space 5 or 10 numbers in case we have to insert something in the middle. ie I need 2 sets of prepends, I'm still learning this stuff so I'll go with 5 and 10. We all started somewhere, we all did dumb stuff, hopefully, we all learned. 12AS hops, I have to go see how they are connected now, maybe someone in that chain needs to be invited by an IX to a NANOG or GPF or some such, that can't be super efficient. -jim On Thu, Jun 22, 2017 at 3:09 AM, Pierfrancesco Caci <pf () tippete net> wrote:"Mel" == Mel Beckman <mel () 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 ------------------------- 0: 340 1: 47522 2: 292879 3: 227822 4: 58390 5: 10217 6: 2123 7: 638 8: 48 9: 58 11: 20 12: 2 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. Pf -- Pierfrancesco Caci, ik5pvx
Current thread:
- Long AS Path James Braunegg (Jun 20)
- Re: Long AS Path Olivier Benghozi (Jun 20)
- Re: Long AS Path Laszlo Hanyecz (Jun 20)
- Re: Long AS Path sthaug (Jun 21)
- Re: Long AS Path Randy Bush (Jun 21)
- Re: Long AS Path Stephen Satchell (Jun 21)
- Re: Long AS Path sthaug (Jun 21)
- Re: Long AS Path Mel Beckman (Jun 21)
- Re: Long AS Path Pierfrancesco Caci (Jun 21)
- Re: Long AS Path jim deleskie (Jun 22)
- Re: Long AS Path Mel Beckman (Jun 22)
- Re: Long AS Path Bob Evans (Jun 21)
- Re: Long AS Path Saku Ytti (Jun 21)
- Re: Long AS Path Jon Lewis (Jun 22)
- Re: Long AS Path Stephen Satchell (Jun 22)
- Re: Long AS Path Ryan L (Jun 23)