BGP advertise multiple paths to the peer.

[nitinraj92]

I was looking for a use case where same subnet is getting imported from different vrfs with different community string. and I want both of the routes to be advertized to the peer.

BGP routing table entry for 1.1.1.0/24, version 67
Paths: (2 available, best #1, table default)
  Advertised to non peer-group peers:
  172.16.3.1
  Imported from 192.168.100.1:11:1.1.1.0/24
  Local
    192.168.100.10 from 0.0.0.0 (3.3.3.3) vrf vrf-black(41) announce-nh-self
      Origin incomplete, metric 100, aigp-metric 100, weight 32768, valid, sourced, local, multipath, best (Locally configured route)
      Community: 100:200
      Originator: 3.3.3.3
      Last update: Thu Sep 12 15:34:54 2024
  Imported from 192.168.100.1:9:1.1.1.0/24
  Local
    192.168.100.10 from 0.0.0.0 (3.3.3.3) vrf vrf-green(40) announce-nh-self
      Origin incomplete, metric 100, aigp-metric 100, weight 32768, valid, sourced, local, multipath
      Community: 100:100
      Originator: 3.3.3.3
      Last update: Thu Sep 12 12:45:38 2024

Since 1 route is selected as best, I am only getting route with community 100:200 on the peer device.

CE1B# show ip bgp 1.1.1.0/24
BGP routing table entry for 1.1.1.0/24, version 37
Paths: (1 available, best #1, table default)
  Advertised to non peer-group peers:
  172.16.4.1
  64501 64401
    172.16.4.1 from 172.16.4.1 (2.2.2.2)
      Origin incomplete, valid, external, best (First path received)
      Community: 100:200
      Last update: Thu Sep 12 16:51:51 2024

Is there any config option to specify to bgp to advertize all routes irrespective of best path? (edited)

[ton31337]

Check this flag: https://docs.frrouting.org/en/stable-10.1/bgp.html#clicmd-neighbor-A.B.C.D-X-X-X-X-WORD-addpath-tx-all-paths.

[nitinraj92]

Thank you for the reply!! it works.