BGP policy

BGP Communities

Use these communities to narrow route export, request AS-path prepend, or understand the source tags bgp43 adds to routes internally.

Open in dashboard Looking Glass
Standard 65535:0 / 65535:65281-65283
Large AS197324
filtered on import 100+ total communities

applied on export

Communities you can send

These values are accepted from approved customer BGP sessions. They can reduce export scope or add prepend, but they never override the session export policy.

65535:0 Standard / accepted on import
Graceful shutdown If you announce a route with 65535:0, bgp43 lowers local preference to 0 while keeping the route eligible.
Can use
65535:65281 Standard / applied on export
Well-known NO_EXPORT Prevents export to external BGP sessions while allowing internal iBGP propagation.
Can use
65535:65282 Standard / applied on export
Well-known NO_ADVERTISE Prevents export to any BGP session, including iBGP.
Can use
65535:65283 Standard / applied on export
Well-known NO_EXPORT_SUBCONFED Handled like NO_EXPORT for bgp43 external sessions.
Can use
197324:100:0 Large / applied on export
Do not export anywhere Blocks export of the route from bgp43 to every BGP session.
Can use
197324:100:1 Large / applied on export
Do not export to upstreams Blocks export of the route to upstream/transit sessions only.
Can use
197324:100:2 Large / applied on export
Do not export to peers or IXPs Blocks export of the route to direct peers and IXP sessions.
Can use
197324:100:3 Large / applied on export
Do not export to downstreams Blocks export of the route to downstream/BYOIP sessions.
Can use
197324:102:<ASN> Large / applied on export
Do not export to ASN Blocks export of the route only to BGP sessions whose remote ASN matches <ASN>.
Can use
197324:101:1 Large / applied on export
AS-path prepend x1 Prepends the bgp43 local ASN once before export.
Can use
197324:101:2 Large / applied on export
AS-path prepend x2 Prepends the bgp43 local ASN twice before export.
Can use
197324:101:3 Large / applied on export
AS-path prepend x3 Prepends the bgp43 local ASN three times before export.
Can use
third-party communities Any / accepted on import
Other communities Non-bgp43 communities are preserved unless the route hits the excessive-community safety limit.
Can use

added by bgp43

Tags bgp43 owns

bgp43 removes user-supplied values in its own large-community namespaces and writes fresh source tags during import.

197324:3:100 Large / added by bgp43
Peer source tag Marks routes learned from direct peer sessions. This community is generated by bgp43; user-supplied values in this namespace are removed.
System managed
197324:3:101 Large / added by bgp43
IXP source tag Marks routes learned from IXP route-server sessions. This community is generated by bgp43; user-supplied values in this namespace are removed.
System managed
197324:3:102 Large / added by bgp43
Transit source tag Marks routes learned from upstream/transit sessions. This community is generated by bgp43; user-supplied values in this namespace are removed.
System managed
197324:3:103 Large / added by bgp43
Downstream source tag Marks routes learned from user downstream sessions. This community is generated by bgp43; user-supplied values in this namespace are removed.
System managed
197324:3:106 Large / added by bgp43
BYOIP source tag Marks routes learned from BYOIP-style user sessions. This community is generated by bgp43; user-supplied values in this namespace are removed.
System managed
197324:301:<ASN> Large / added by bgp43
Source ASN tag Stores the remote ASN that supplied the route. This community is generated by bgp43; user-supplied values in this namespace are removed.
System managed
100+ total communities Any / filtered on import
Excessive communities A route with too many communities is accepted only after standard, extended and large communities are cleared. Routes with 100 or more total standard, extended and large communities have all communities stripped.
Cannot use

Policy notes

Import On import, bgp43 removes its own large-community source namespace from user routes, then writes fresh source tags.
Export Export communities can only make export narrower or prepend AS-path. They cannot bypass the session export policy.
Safety limit The community safety limit protects routers from oversized attribute sets before normal route validation continues.