On Tue, Dec 01, 2015 at 02:53:05PM -0800, Warren Turkal wrote:

Hi networkers,

I'd like to use bgp extended communities instead of communities for my routing policy so that I can use the 4-octet ASN. However, I am a bit confused by the route target vs route origin (and not having other kinds). Would it be appropriate to use the route origin (as opposed to the route target) kind of ECs to hold the community data that I will use for routing policies? Or maybe is there a way to use the generic 0x04 sub type instead of ro and rt kinds?

Hi Unfortunately, BGP extended communities are unncecessary complex. But you can use any community in any way you want as long as you are using your 4-octet ASN. Currently, route-target and route-origin are just labels with no internal meaning in BIRD. Generic extended community based on draft-ietf-idr-as4octet-extcomm-generic-subtype is not yet implemented in syntax, but you can probably use 'unknown 4' for that or use 'generic' keyword for any ext. comm. with some low-level hacking. These are not explicitly documented, but are used in filter test config: https://gitlab.labs.nic.cz/labs/bird/blob/master/filter/test.conf Unfortunately, authors of ext.comm. specification do not foresee that with 4-octet ASNs and typed communities people would need both 4-octet global part and 4-octet local part, therefore (with type header) 10 octets instead of 8 octets per ext.comm. And they did not include equivalent of basic community in the main ext.comm. specification.

Also, is it legitimate to use some private ASN for global communities that can be set by any of my routers when talking to one another?

Probably yes as long as you filter out them on AS borders. -- 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."