BGP Communities
This topic describes the BGP communities that can be used to control routing policy. For example, peers can tag their routes to the route servers to adjust the route preference on the network or to control the distribution of advertised prefixes. This can be useful in cases where you want to peer with the entire IX except for one or two specific networks.
You can also filter routes based on a geographic location by specifying a METRO_ID. For a list of IDs, see Metro IDs.
MegaIX route servers support a number of traffic engineering communities to assist peers in controlling route preference and distribution. BGP communities in the range
64990-65512:*
are stripped while all others are passed on to peers.
BGP community values
You can use standard BGP communities to define export policy to peers with 2-byte ASNs, and extended BGP communities for both 2-byte and 4-byte ASN peers.
| Standard BGP Community Value | Extended BGP Community Value | Large BGP Community Value | Description |
|---|---|---|---|
| Action | |||
| 65000:0 | rt:65000:0 | RS_ASN:65000:0 | Do not announce this route to any ASN |
| 65000:ASN | rt:65000:ASN | RS_ASN:65000:ASN | Do not announce this route to ASN |
| 64960:ASN | rt:64960:ASN | RS_ASN:64960:ASN | Do announce this route to ASN if (65000:0) is set |
| 65001:0 | rt:65001:0 | RS_ASN:65001:0 | Prepend peer AS 1 time to all |
| 65001:ASN | rt:65001:ASN | RS_ASN:65001:ASN | Prepend peer AS 1 time to ASN |
| 65002:0 | rt:65002:0 | RS_ASN:65002:0 | Prepend peer AS 2 time to all |
| 65002:ASN | rt:65002:ASN | RS_ASN:65002:ASN | Prepend peer AS 2 time to ASN |
| 65003:0 | rt:65003:0 | RS_ASN:65003:0 | Prepend peer AS 3 time to all |
| 65003:ASN | rt:65003:ASN | RS_ASN:65003:ASN | Prepend peer AS 3 time to ASN |
| 65050:0 | rt:65050:0 | RS_ASN:65050:0 | Do not announce this route to local peers |
| 65050:1 | rt:65050:1 | RS_ASN:65050:1 | Do not announce this route to remote peers |
| 65070:0 | rt:65070:0 | RS_ASN:65070:0 | Do not send this route to any METRO_ID |
| 65070:METRO_ID | rt:65070:METRO_ID | RS_ASN:65070:METRO_ID | Do not send this route to METRO_ID |
| 64970:METRO_ID | rt:64970:METRO_ID | RS_ASN:64970:METRO_ID | Do announce this route to METRO_ID if (64970:0) is set |
| Informational actions are advertised to the peers on route export: | |||
| 65040:0 | Not used | Not used | This route comes from a local peer |
| 65040:1 | Not used | Not used | This route comes from a remote peer |
| 65060:METRO_ID | Not used | Not used | This route comes from a peer in METRO_ID |
Euro-IX communities
Large communities
| BGP Community Value | Description |
|---|---|
| Action | |
| RS_ASN:0:ASN | Do not announce this route to ASN |
| RS_ASN:0:0 | Do not announce this route to any ASN |
| RS_ASN:1:ASN | Do announce this route to ASN if (65000:0) is set |
| RS_ASN:101:0 | Prepend peer AS 1 time to all |
| RS_ASN:101:ASN | Prepend peer AS 1 time to ASN |
| RS_ASN:102:0 | Prepend peer AS 2 times to all |
| RS_ASN:102:ASN | Prepend peer AS 2 times to ASN |
| RS_ASN:103:0 | Prepend peer AS 3 times to all |
| RS_ASN:103:ASN | Prepend peer AS 3 times to ASN |
| Informational actions are advertised to the peers on route export: | |
| RS_ASN:1900:0 | This route comes from a local peer |
| RS_ASN:1900:1 | This route comes from a local peer |
| RS_ASN:1903:METRO_ID | This route comes from a peer in METRO_ID |