BGP Communities Question.

[davidcriollo]

Hi everyone, Please help with this question.

I have set the No_Export Comminities feature to the Prefix 10.1.1.0/24 in R2 int he inbound direction 

R2(config-route-map)#do show bgp 10.1.1.0/24
BGP routing table entry for 10.1.1.0/24, version 2
Paths: (1 available, best #1, table default, not advertised to EBGP peer)
Advertised to update-groups:
10
Refresh Epoch 1
65100
10.12.1.1 from 10.12.1.1 (192.168.1.1)
Origin incomplete, metric 0, localpref 100, valid, external, best
Community: no-export
rx pathid: 0, tx pathid: 0x0

--------------------------------------------------------------------------------------

R4 and R5 are still learning that prefix but they are not including the Comunity feature and in consequence R3 (AS65300) is still learning it. 

R4#show bgp ipv4 unic 10.1.1.0/24
BGP routing table entry for 10.1.1.0/24, version 6
Paths: (1 available, best #1, table default)
Not advertised to any peer
Refresh Epoch 2
65100
10.12.1.1 from 10.13.1.1 (10.13.1.1)
Origin incomplete, metric 0, localpref 100, valid, internal, best
rx pathid: 0, tx pathid: 0x0

R5#show bgp 10.1.1.0/24
BGP routing table entry for 10.1.1.0/24, version 10
Paths: (1 available, best #1, table default)
Advertised to update-groups:
4
Refresh Epoch 2
65100
10.12.1.1 from 10.13.1.1 (10.13.1.1)
Origin incomplete, metric 0, localpref 100, valid, internal, best
rx pathid: 0, tx pathid: 0x0

------------------------------------

R3 AS65300

R3#show bgp ipv4 unicast 10.1.1.0/24
BGP routing table entry for 10.1.1.0/24, version 21
Paths: (1 available, best #1, table default)
Not advertised to any peer
Refresh Epoch 1
65200 65100
10.23.1.1 from 10.23.1.1 (1.1.1.1)
Origin incomplete, localpref 100, valid, external, best
rx pathid: 0, tx pathid: 0x0

[M02@rt37 · Accepted solution]

Hello @davidcriollo,

If you want the 'no-export' community to be effective within AS65200 (e.g., between R2 and R3), you would indeed need to configure 'send-community both' command on the iBGP peers (R2 and R3 in this case).

Note that with IOS, communities are not sent, except if 'send-community' command is configured.

Whereas with IOS-XR, communities are sent by default on iBGP session but not with eBGP sessions.

router bgp <asn>
neighbor <ip> remote-as <asn>
neighbor <ip> send-community both

[davidcriollo]

Yeap. It resolved the issue, Thanks a lot. 

[M02@rt37]

You're welcome @davidcriollo