On 3/29/2018 2:22 AM, Andy Litzinger 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 route had been withdrawn.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?
If your global provider supports, you could send your announcements with a BGP community per RFC1998 telling them to not-prefer-so-much that advertisement, "use it as a backup". that would shift a lot of incoming traffic to the other link (regional provider). You'll still have the global provider link. this is a smaller change towards taking global provider offline, keeping some fallback. Frank
