On 2015-04-15, Mike Hammett <openbsd-m...@ics-il.net> wrote: > With the decline of OpenBGPd's popularity among IXPs, it's difficult > to track down examples of how IXPs are configuring their servers. I saw > a couple presentations in the 2010 - 2011 timeframe with new things that > were coming for 32 bit communities among other things.
Common IXP setup is to use transparent-as, and to support fine control of where routes are sent by tagging with communities. The latter requires using separate RIBs per peer (when a filter prevents the route server's "best route" from being sent to a particular peer you want another route to be sent instead). AFAIK most IXPs that stopped using OpenBGPd did so because of slow convergence times when filtering many routes. Prior to doing this, the one that I know about had already split to separate daemon instances for v4 and v6 to spread the work amongst more cores. They ran into some other problems (debuggable/fixable) but that was the killer. Current best practice for 32 bit communities is "if you're doing communities-based filtering, hand back the ASN and exchange it for a 16 bit one". Seriously. There are "extended communities" but they suffer the IPv6 problem of changing too much, plus they don't even solve the problem (they're 16 + 32 bit, where what is needed is 32 + 32 bit).
