On Thu, Mar 06, 2014 at 10:25:20PM +0200, Alexander Shikov wrote:
Now let's assume that 109.68.40.0/21 is reachable via other peer, and we got new route, and it is better due to as-path length, and new peer does not want to blackhole 109.68.40.20. Then "109.68.40.0/21 via 193.25.180.17" will become inactive, but "109.68.40.20/32 via 193.25.181.253 from 193.25.180.17" will stay best, and new peer will lose traffic to 109.68.40.20.
Thus, it'd be reasonable to compare received /32 against routing table, and accept it only if there is active less-specific route from same peer. Personally I was not able to find solution for bird. Now I'm wondering how do other IXPs perform such filtering?
Hello That is not currently possible, as BIRD processes routes independently. Also note that you can filter again [ 109.68.40.0/21, 109.68.40.0/21{32,32} ], which would allow both 109.68.40.0/21 and 109.68.4X.X/32, but not intermediate prefixes, but this does not help w.r.t. your main concern - a route from another peer. -- Elen sila lumenn' omentielvo Ondrej 'SanTiago' Zajicek (email: santiago@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."