nanog mailing list archives
Re: validating reachability via an ISP
From: Andrew Wentzell <awentzell () gmail com>
Date: Thu, 29 Mar 2018 10:51:37 -0400
On Wed, Mar 28, 2018 at 7:22 PM, Andy Litzinger <andy.litzinger.lists () gmail com> wrote:
Hi all, I have an enterprise network and do not provide transit. In one of our datacenters we have our own prefixes and rely on two ISPs as BGP neighbors to provide global reachability for our prefixes. One is a large regional provider and the other is a large global provider. Recently we took our link to the global provider offline to perform maintenance on our router. Nearly immediately we were hit with alerts that our prefix was unreachable and BGPMon alerted that nearly 80 AS's noted our route had been withdrawn. We were not unreachable from every AS, but we certainly were from some of the largest. The root cause is that the our prefix is not being adequately re-distributed globally by the regional ISP. This is unexpected and we are working through this with them now. My question is, how can I monitor global reachability for a prefix via this or any specific provider I use over time? Are there various route-servers I can programmatically query for my prefix and get results that include AS paths? Then I could verify that an "acceptable" number of paths exist that include the AS of the all the ISPs I rely upon. And what would an "acceptable" number of alternate paths be?
I did something similar a few years ago, by querying routeviews and validating AS paths using python and pexpect. You could adapt it for your use pretty easily. The code's here: https://github.com/awentzell/check-as-path
Current thread:
- validating reachability via an ISP Andy Litzinger (Mar 28)
- Re: validating reachability via an ISP Frank Habicht (Mar 28)
- Re: validating reachability via an ISP Baldur Norddahl (Mar 29)
- Re: validating reachability via an ISP Andrew Wentzell (Mar 29)
- Re: validating reachability via an ISP Alexander Azimov (Mar 29)
- <Possible follow-ups>
- Re: validating reachability via an ISP Baldur Norddahl (Mar 29)