BGP policy
BGP Communities
Use these communities to narrow route export or request AS-path prepend, and read the source tags bgp43 adds to every route it learns.
accepted on import
Communities you can send
Attach these values to routes you announce over a customer or BYOIP session. They can narrow export or add prepend; they never widen the session export policy.
65535:0StandardGraceful shutdown
bgp43 lowers local preference to 0 while keeping the route eligible, so traffic moves to another path before you shut the session down.
Can use
65535:65281StandardWell-known NO_EXPORT
The route stays inside bgp43 and is not exported to any external BGP session.
Can use
65535:65282StandardWell-known NO_ADVERTISE
The route is not exported to any BGP session, including bgp43's own routers.
Can use
65535:65283StandardWell-known NO_EXPORT_SUBCONFED
Treated like NO_EXPORT: the route is not exported to any external BGP session.
Can use
197324:100:0LargeDo not export anywhere
Blocks export of the route to every external BGP session.
Can use
197324:100:1LargeDo not export to upstreams
Blocks export of the route to upstream/transit sessions only.
Can use
197324:100:2LargeDo not export to peers or IXPs
Blocks export of the route to direct peers and IXP sessions.
Can use
197324:100:3LargeDo not export to downstreams
Blocks export of the route to other customers' downstream and BYOIP sessions.
Can use
197324:102:<asn>LargeDo not export to ASN
Blocks export of the route only to BGP sessions whose remote ASN is <asn>.
Can use
197324:101:1LargeAS-path prepend x1
Prepends the bgp43 ASN once on export to external sessions.
Can use
197324:101:2LargeAS-path prepend x2
Prepends the bgp43 ASN twice on export to external sessions.
Can use
197324:101:3LargeAS-path prepend x3
Prepends the bgp43 ASN three times on export to external sessions. When several prepend values are set, the largest one applies.
Can use
System managed
Tags bgp43 owns
bgp43 writes these on import. Values you send in these namespaces are replaced, and routes from upstreams, peers and IXPs lose every community in the bgp43 namespace.
197324:3:100LargePeer source tag
Marks routes learned from direct peer sessions.
System managed
197324:3:101LargeIXP source tag
Marks routes learned from IXP route-server sessions.
System managed
197324:3:102LargeTransit source tag
Marks routes learned from upstream/transit sessions.
System managed
197324:3:103LargeDownstream source tag
Marks routes learned from customer downstream sessions.
System managed
197324:3:105LargeiBGP source tag
Marks routes learned from another bgp43 router.
System managed
197324:3:106LargeBYOIP source tag
Marks routes learned from BYOIP sessions and static BYOIP routes.
System managed
197324:301:<asn>LargeSource ASN tag
Stores the remote ASN of the session that supplied the route.
System managed
BGP policy
Policy notes
Import
Customer and BYOIP routes keep the action and prepend communities they carry; their source tags are rewritten. Routes from upstreams, peers and IXPs lose every community in the bgp43 namespace.
Export
Action and prepend communities apply where a route leaves bgp43 and are removed from it there. bgp43's own routers always receive the route, so the action is honoured on every router.
Safety limit
A route that arrives with 100 or more standard, extended and large communities in total has all of them cleared before validation continues.