topic Re: Need to exclude some prefixes from no-export community in BGP in Data Center (MLX & CER/CES)

Need to exclude some prefixes from no-export community in BGP

ddpatil89 — Thu, 27 Aug 2020 12:49:47 GMT

I am (AS 24029) advertising all the prefixes received via one of the EBGP peer (As 10029) to my one of the EBGP peer (AS 9498) with no-export community set.

(AS 10029) <----received routes---->(AS 24029)<----advertised routes with no-export community--->(AS 9498)

Now I need to advertise below 2 networks without no-export community.

1. 180.151.0.0/24
2. 125.63.64.0/24

Please let me know how to achieve it.

BGP configuration running currently on MLXe-8

router bgp
local-as 24029

neighbor IXP-peers peer-group
neighbor IXP-peers password 2 $WFMrM2c9Qz0xPUNTSQ==
neighbor IXP-peers soft-reconfiguration inbound

neighbor 218.100.48.10 remote-as 10029
neighbor 218.100.48.10 peer-group IXP-peers
neighbor 218.100.48.10 description ISP-Citycom

neighbor 218.100.48.20 remote-as 9498
neighbor 218.100.48.20 peer-group IXP-peers
neighbor 218.100.48.20 description Bharti-Airtel

address-family ipv4 unicast
neighbor IXP-peers route-map out set-no-export
neighbor IXP-peers send-community

route-map set-no-export permit 10
set community no-export

Re: Need to exclude some prefixes from no-export community in BGP

joergkost — Thu, 27 Aug 2020 12:58:45 GMT

Do you have any other peers on that router?

I would also recommend you, to re-edit your posting and remove at least the password phrase. You can also alter the IP addresses, e.g. peer-48.10 would be enough to understand.

Re: Need to exclude some prefixes from no-export community in BGP

ddpatil89 — Thu, 27 Aug 2020 13:07:28 GMT

Yes. We have many peers on the router all having no-export community set. I only pasted configuration for which i required help.

Re: Need to exclude some prefixes from no-export community in BGP

joergkost — Thu, 27 Aug 2020 14:02:19 GMT

Seeing the configuration snippets from above, I would assume the following will work for you:

ip prefix-list export-routes-as9498 seq 50 permit 180.151.0.0/24
ip prefix-list export-routes-as9498 seq 100 permit 125.63.64.0/24

route-map as9498-out permit 25
 match ip address prefix-list export-routes-as9498
route-map as9498-out permit 50
 set community  no-export

router bgp
# replace outside route-map
neighbor 218.100.48.20 route-map out as9498-out

# exec mode
clear ip bgp neighbor 218.100.48.20 (soft? hard? depends on current state)