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FAQ

Why eBGP does not connect to loopback address?​

eBGP by default can connect only one hop away. Loopback address is plus one more hop, because it is routed over the connected network. For multihop sessions set multihop=yes. *

What does BGP network synchronization exactly mean?​

BGP will not announce the network unless there is a matching active IGP or connected route (exact prefix match) in the routing table. The main reason for synchronization is to avoid routing loops. If IGP is not reliable or it is necessary to always advertise the network, then add static blackhole route for each network prefix to be advertised or set output.network-blackhole=yes in /routing/bgp/connection configuration to automatically add active blackhole route for each BGP network.

How to hide my own AS?​

Peer's own AS is removed from AS_PATH if output.default-prepend in /routing/bgp/connection configuration is set to 0 or bgp-path-prepend is set to 0 in output routing filters.

Remote peer prepends its AS several times. How to override the prepend?​

Remote peers prepend can be removed by setting bgp-path-peer-prepend 1 in BGP input routing filter.

BGP does not pick route with shortest AS path or other metrics are ignored.​

BGP best path selection works only on routes received by the same BGP instance.

BGP routes received from one peer is not advertised to other peer.​

Most common misconfiguration:

  • Output filter is blocking redistribution.
  • Both peers do not running on the same BGP instance.