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New Member

bgp communities

Hi'

I'm seting up a test lab for bgp communities i.e no-export attribute,

i have following setup; 2500 as200---3640as100---as1002600---2500as10.

I configured routing policy for the AS10 that allows subnet 172.16.1.0/172.17.1.0 to be advertised to AS100, but not to any of the EBGP peer connected to 3640 router by using no-export community attribute.

However this doen't work. I have attached config and bgp routing.

The 2600 router advertises above routes to its local peers "3640", but the 3640 doesn't honor the no-export attributes and adversites 172.17.1.0/172.16.10 routes to EBGP peers AS200.

AS100-3640

router bgp 100

no synchronization

bgp log-neighbor-changes

network 192.168.1.0

network 192.168.2.0

neighbor CLIENTS peer-group

neighbor CLIENTS ebgp-multihop 2

neighbor CLIENTS update-source Loopback0

neighbor CLIENTS default-originate

neighbor CLIENTS soft-reconfiguration inbound

neighbor LOCAL peer-group

neighbor LOCAL remote-as 100

neighbor LOCAL update-source Loopback0

neighbor LOCAL next-hop-self

neighbor LOCAL soft-reconfiguration inbound

neighbor 10.1.255.2 remote-as 200

neighbor 10.1.255.2 peer-group CLIENTS

neighbor 10.1.255.6 remote-as 400

neighbor 10.1.255.6 peer-group CLIENTS

neighbor 10.1.255.10 remote-as 300

neighbor 10.1.255.10 peer-group CLIENTS

neighbor 10.1.255.13 peer-group LOCAL

no auto-summary

!

ip classless

ip route 10.1.255.2 255.255.255.255 10.1.1.1

ip route 10.1.255.6 255.255.255.255 10.1.3.1

ip route 10.1.255.10 255.255.255.255 10.1.2.1

ip route 10.1.255.13 255.255.255.255 194.200.1.2

AS100-3640#sh ip bgp community no-export

AS100-3640#

AS100-3640#sh ip bg 172.17.1.0

BGP routing table entry for 172.17.1.0/24, version 117

Paths: (1 available, best #1)

Advertised to peer-groups:

CLIENTS

10, (received & used)

10.1.255.13 from 10.1.255.13 (10.1.255.13)

Origin IGP, metric 0, localpref 100, valid, internal, best

AS100-3640#sh ip bg 172.16.1.0

BGP routing table entry for 172.16.1.0/24, version 116

Paths: (1 available, best #1)

Advertised to peer-groups:

CLIENTS

10, (received & used)

10.1.255.13 from 10.1.255.13 (10.1.255.13)

Origin IGP, metric 0, localpref 100, valid, internal, best

C2600

router bgp 100

no synchronization

bgp log-neighbor-changes

network 172.15.1.2 mask 255.255.255.0

neighbor 10.1.255.1 remote-as 100

neighbor 10.1.255.1 update-source Loopback0

neighbor 10.1.255.1 next-hop-self

neighbor 10.1.255.1 soft-reconfiguration inbound

neighbor 10.1.255.14 remote-as 10

neighbor 10.1.255.14 ebgp-multihop 2

neighbor 10.1.255.14 update-source Loopback0

no auto-summary

!

ip classless

ip route 10.1.255.1 255.255.255.255 194.200.1.1

ip route 10.1.255.14 255.255.255.255 193.123.116.67

no ip http server

C2600-AS100#sh ip bg community no-ex

C2600-AS100#sh ip bg community no-export

BGP table version is 108, local router ID is 10.1.255.13

Network Next Hop Metric LocPrf Weight Path

*> 172.16.1.0/24 10.1.255.14 0 0 10 i

*> 172.17.1.0/24 10.1.255.14 0 0 10 i

C2600-AS100#

C2600-AS100#sh ip bg

BGP table version is 108, local router ID is 10.1.255.13

Network Next Hop Metric LocPrf Weight Path

*>i10.0.0.0 10.1.255.1 0 100 0 300 i

*>i140.60.0.0 10.1.255.1 0 100 0 200 i

*>i142.60.0.0 10.1.255.1 0 100 0 400 i

*> 172.14.1.0/24 10.1.255.14 0 0 10 i

*> 172.15.1.0/24 10.1.255.14 0 0 10 i

*> 172.16.1.0/24 10.1.255.14 0 0 10 i

*> 172.17.1.0/24 10.1.255.14 0 0 10 i

*>i192.168.1.0 10.1.255.1 0 100 0 i

*>i192.168.2.0 10.1.255.1 0 100 0 i

C2600-AS100#

C2500-AS200

router bgp 200

network 140.60.0.0

neighbor 10.1.255.1 remote-as 100

neighbor 10.1.255.1 ebgp-multihop 2

neighbor 10.1.255.1 update-source Loopback0

neighbor 10.1.255.1 soft-reconfiguration inbound

C2500-AS200#sh ip bg

BGP table version is 74, local router ID is 10.1.255.2

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 10.1.255.1 0 100 i

*> 10.0.0.0 10.1.255.1 0 100 300 i

*> 140.60.0.0 0.0.0.0 0 32768 i

*> 142.60.0.0 10.1.255.1 0 100 400 i

*> 172.14.1.0/24 10.1.255.1 0 100 10 i

*> 172.15.1.0/24 10.1.255.1 0 100 10 i

*> 172.16.1.0/24 10.1.255.1 0 100 10 i

*> 172.17.1.0/24 10.1.255.1 0 100 10 i

*> 192.168.1.0 10.1.255.1 0 0 100 i

*> 192.168.2.0 10.1.255.1 0 0 100 i

C2500-AS10

router bgp 10

network 172.17.1.0 mask 255.255.255.0

network 172.16.1.0 mask 255.255.255.0

network 172.15.1.0 mask 255.255.255.0

network 172.14.1.0 mask 255.255.255.0

neighbor 10.1.255.13 remote-as 100

neighbor 10.1.255.13 ebgp-multihop 2

neighbor 10.1.255.13 update-source Loopback0

neighbor 10.1.255.13 send-community

neighbor 10.1.255.13 soft-reconfiguration inbound

neighbor 10.1.255.13 route-map newmexico out

no auto-summary

!

ip classless

ip route 10.1.255.13 255.255.255.255 193.123.116.66

!

access-list 1 permit 172.17.1.0

access-list 1 permit 172.16.1.0

route-map newmexico permit 10

match ip address 1

set community no-export

!

route-map newmexico permit 20

C2500-AS10#sh ip bg

BGP table version is 16, local router ID is 10.1.255.14

Network Next Hop Metric LocPrf Weight Path

*> 10.0.0.0 10.1.255.13 0 100 300 i

*> 140.60.0.0 10.1.255.13 0 100 200 i

*> 142.60.0.0 10.1.255.13 0 100 400 i

*> 172.14.1.0/24 0.0.0.0 0 32768 i

*> 172.15.1.0/24 0.0.0.0 0 32768 i

*> 172.16.1.0/24 0.0.0.0 0 32768 i

*> 172.17.1.0/24 0.0.0.0 0 32768 i

*> 192.168.1.0 10.1.255.13 0 100 i

*> 192.168.2.0 10.1.255.13 0 100 i

Regards

Abdi

  • Other Network Infrastructure Subjects
6 REPLIES
Cisco Employee

Re: bgp communities

I don't see the community on the 3640 in the 'sh ip bgp x.x.x.x'

So, try to clear bgp session between as 10 and 3640.

New Member

Re: bgp communities

Hi,

I did try that, no difference. May be it's code issue ???.

The 3640 is running flash:c3640-is-mz.122-8.T.bin

and 2600 is running flash:c2600-i-mz.121-5.T12.bin".

2500 is 11.2 ver.

Re: bgp communities

Did you add on the as100 2600 router "neighbor x.x.x.x send-community"?

New Member

Re: bgp communities

I have added send-community on the 2600, and it's working now.

However i though no-export attributes allows route to be adversited throughout the neighouring iBGP AS but not to EBGP AS systems !!!!.

Re: bgp communities

It does allow it to be advertised to the neighbouring IBGP AS and not to the EBGP as you thought.

But as the router (as100 2600) isn't directly peering with the EBGP, it needs to have the send-community command to let it's IBGP peer know what to do. If the router was directly peering with the EBGP, it would have worked.

New Member

Re: bgp communities

Just to say thanks for your help.

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