On Mon, Jul 04, 2016 at 12:15:18PM +0200, Job Snijders wrote:
On Mon, Jul 04, 2016 at 12:02:59PM +0200, Ondrej Zajicek wrote:
By RFC 4271, BGP message is limited to 4 kB of length. BIRD internally limits attribute part of a transmitted message to 2 kB. This is equivalent of 1024 (4 kB) or 512 (2 kB) communities.
You could replace constants 3072 [1] and 2048 [2] with say 3840 and 3584, that would allow 3.5 kB of attributes (~ 900 communities).
[1] proto/bgp/packets.c:372 and proto/bgp/packets.c:465 [2] proto/bgp/packets.c:385 and proto/bgp/packets.c:481
Do you have https://tools.ietf.org/html/draft-ietf-idr-bgp-extended-messages-12 on your roadmap? This draft bumps the 4 kB limit to ~ 65 kB.
It is already mostly [*] supported in 1.6.0, but it needs to be supported by both sides and does not solve this issue for route servers of IXPs unless everyone has the support. [*] well, it allows 64 kB messages but i forgot about the internal 2 kB limit for attributes, so it is currently not much useful. Will be fixed in the next version. -- 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."