BGP community value is not getting to the value set by route-map

[Thiyagarajan K]

Hello All,

I'm troubleshooting an issue with a community attribute in BGP. The community value which has been set for prefix using route-map is not propagated to the neighbour EBGP routers.

Could you please help me to isolate the cause of the issue and let me know what needs to be done to fix the issue?

Configuration:

!
route-map TEST-COMMUITY1 permit 10
set community 10:20 additive
!

router bgp 10
bgp log-neighbor-changes
network 30.0.0.0 mask 255.255.255.0 route-map TEST-COMMUITY1

BGP table output

------------------------------------------------------------------------------
BGP routing table entry for 30.0.0.0/24, version 2
Paths: (2 available, best #2, table default)
Advertised to update-groups:
2
Refresh Epoch 4
10 30
10.10.10.9 from 10.10.10.9 (10.255.0.54)
Origin IGP, localpref 100, valid, external
Community: 655380
rx pathid: 0, tx pathid: 0
Refresh Epoch 2
30
10.10.10.18 from 10.10.10.18 (10.255.0.56)
Origin IGP, metric 0, localpref 100, valid, external, best
rx pathid: 0, tx pathid: 0x0

Regards,

Thiyagu

[Georg Pauwen]

Hello,

make sure you have

ip bgp-community new-format 

configured on your router.

That will change the community 655380 to what you have configured, 10:20

[Richard Burts]

The suggestion about using bgp-community new-format is a good one. But I wonder if it addresses the original problem. As I read the original post it seems that the community is not propagated not so much that it is the wrong format. I wonder if including send community in the BGP config is not also required.

HTH

Rick

[Georg Pauwen]

Richard,

I might have missed something, not sure. I thought the community that is shown in the output, 655380, was the one that is propagated, just not in the right format...?

655380 --> 10100000000000010100

1010 : 0000000000010100 = 10:20

which would be the community set in the route map...

[Richard Burts]

My understanding of the original post is that the community is not propagated. Perhaps what was intended was that it was not in the expected format and therefore seems not propagated. We need clarification from the original poster about this.

HTH

Rick

[Thiyagarajan K]

Thanks a lot guys for your valuable inputs. My issue was the community propagation was not in the correct format. my expected community value is 10:20 but I'm finding the value of  655380 on the neighbor router.

do I need to add the command "ip bgp-community new-format" on the neighbour router?

!

ip http authentication local
no ip http secure-server
!
ip bgp-community new-format
!
!

Regards,

Thiyagau

[Richard Burts]

Thiyagau

Thank you for clarifying that the real issue was the format in which the community was displayd. So the suggestion about specifying ip bgp-community new-format was the better suggestion.

The ip bgp-community new-format command controls the display of the community value. So it would be important that the neighbor router have this command. It would probably be advisable if your router had the command also. You can use this link to find additional details

http://www.cisco.com/c/en/us/td/docs/ios/iproute_bgp/command/reference/irg_book/irg_bgp2.html

HTH

Rick

[Thiyagarajan K]

Thanks a lot all for your quick help. Adding the command "ip bgp-community new-format" took care of the issue.

Regards,

Thiyagu

[Richard Burts]

Thiyagu

Thanks for posting back and confirming that adding the ip bgp-community new-format did solve your problem. So it would be appropriate to mark this question as answered.

HTH

Rick

[Thiyagarajan K]

Rick,

Please mark as answered and thanks again for your prompt reply.

Thanks,

Thiyagu

[Richard Burts · Accepted solution]

Thiyagu

Marking a question as answered can be done only by the original poster.

HTH

Rick