BGP communities
RoutedBits tags every route it sends you with informational communities, and honors a set of action communities you can attach to your announcements to control how they're propagated across the network.
Communities are expressed as large communities in the form (4242420207, function, parameter), where 4242420207 is the RoutedBits ASN. DN42's standard routing-policy communities are also honored where noted below.
Informational communities
Set by RoutedBits on routes advertised to you. Use them to reason about path quality and origin — they're advisory and never required.
| Community | Meaning |
|---|---|
| 64511:<d42_region> | DN42 Region (only set on originated routes) |
| 4242420207:100:404 | RPKI not-found route (Local Preference set 80) |
| 4242420207:100:666 | Soft-failed RPKI route (used internally) |
| 4242420207:120:<instance_id> | RB router this route was learned on |
| 4242420207:130:1 | Direct peer |
| 4242420207:140:<dn42_region> | DN42 region ID we learned this route |
Action communities
Attach these to routes you announce to RoutedBits to control how they're re-advertised. They're applied in order and can be combined.
| Community | Effect |
|---|---|
| 65535:65281 | Well-known no-export (Do not advertise outside AS) |
| 65535:65282 | Well-known no-advertise (Do not advertise anywhere) |
| 65535:666 | Well-known blackhole community |
| 4242420207:500:<1-4> | Prepend AS 1-4 times when advertising to peers |
| 4242420207:600:<dn42_region> | Do not advertise to DN42 region |
Region IDs
Used as the region parameter in region-scoped communities above.
| ID | Region | ID | Region |
|---|---|---|---|
| 1 | Europe | 4 | Africa |
| 2 | North America | 5 | Asia |
| 3 | South America | 6 | Oceania |
Setting communities
Add the large community to matching routes in your export filter. For example, to prepend twice to everyone and blackhole a single host:
# prepend AS4242420207 twice toward all peers add-large-community(4242420207, 500, 2); # blackhole a /32 you originate if route matches 172.20.19.128/32 then add-large-community(4242420207, 666, 1);