Details of the BGP communities supported by the burble.dn42 network.

DN42 Communities

DN42 Communities are applied both internally and externally, and are used to influence the Routing Policy.

Community   Description
( 64511 : 0 < x < 21 )   Max latency
( 64511 : 20 < x < 30 )   Min bandwidth
( 64511 : 30 < x < 35 )   Min encryption
( 64511 : 40 < x < 54 )   Route Origin

Well Known BGP Communities

The following well known communities are implemented.

Community   Description Action
( 65535 : 65281 )   No Export Prefix should not be exported outside of AS4242422601
( 65535 : 65282 )   No Advertise   Prefix should not be exported to any peers
( 65535 : 65283 )   Local-AS Prefix should not be exported outside of region

burble.dn42 Specific Communities

burble.dn42 implements large BGP communities, with ISO 3166-1 / UNSD country, and UNSD region codes.

Informational Communities

Community   Description
( 4242422601 : 120 : host code )   Route learned on this host
( 4242422601 : 130 : 1 )   Route is a direct peer
( 4242422601 : 140 : DN42 region )   Route learned in this DN42 region

 

Ghost Route Protection

In a large network like burble.dn42 it can take some time for route updates to be distributed and for the network to settle following changes. This can be particularly noticeable when routes are deleted as it can create a cascade of ghost updates, each with an increasing internal path length as the route removal spreads across the network.

To protect against ghost routes, a community is used to track how many internal hops a route has. In a fully meshed network like burble.dn42, a genuine route should never have more than two internal hops, so an export filter is used to prevent distribution of longer paths.

Community   Description
( 4242422601 : 100 : 1 )   Added on first internal re-distribution
( 4242422601 : 100 : 2 )   Added on second re-distribution and prevents further re-distribution within burble.dn42

 

The ( 4242422601 : 100 : x ) communities are not exported to peers.