ebgp mpls question

[marcusbrutus]

Hi Experts,

I've been struggling with this setup and couldn't get it to work.

The idea basically is to establish ebgp mpls peering between two different AS.  There shouldn't be any global table entries.

I am able to get as far as the vpnv4 vrf summ showing as active but it can't seem to peer successfully.  I am able to do "ping vrf test ip 192.168.2.2 source 192.168.1.1 successfully from router1 so I am sure there is no issue in connectivity between loopbacks.

Please see below config of R1.

ip vrf test

rd 10:100

route-target import 20:200

route-target export 10:100

int l0

ip vrf forwarding test

ip add 192.168.1.1 255.255.255.0

int f0/0

ip vrf forwarding test

ip add 1.1.1.1 255.255.255.0

route ospf 10 vrf test

network 1.1.1.0 0.0.0.255 area 0

network 192.168.1.0 0.0.0.255 area 0

router bgp 10

neighbor 192.168.2.2 remote-as 20

neighbor 192.168.2.2 update-source l0

    address-family vpnv4

     neighbor 192.168.2.2 active

     neighbor 192.168.2.2 next-hop-self

     neighbor 192.168.2.2 send-community both

     address-family ipv4 vrf test

     neighbor 192.168.2.2 remote-as 20

     neighbor 192.168.2.2 ebgp-multihop 255

     neighbor 192.168.2.2 activate

***************************************

Same setup on peer router only with different IPs specified ofcourse.

I saw some configs for ebgp mpls but the loopback address was not included in the vrf.

Would really appreciate anyone's help on this.

Thanks in advance.

[Vaibhava Varma]

Hi marcusbrutus

Please add the "update-source lo0 " for the neighbour statement under VRF context on both routers to solve your issue.

The Problem here is that we are trying to peer over Loopback IPs but the Source of BGP Open message is going to be the interface ip which is a mismatch and keeping the session active.

Hope this answers your query.

Regards

Varma

[Kishore Chennupati · Accepted solution]

As Vaibhava mentioned. the following needs to be added.

   address-family ipv4 vrf test

     neighbor 192.168.2.2 remote-as 20  update-source lo0

     neighbor 192.168.2.2 ebgp-multihop 255

     neighbor 192.168.2.2 activate

I saw some configs for ebgp mpls but the loopback address was not included in the vrf.

This is when you don't use the loopbacks for the BGP peering and you use the physical interface IP. In your example

it would the following config assuming that the peer ip is 1.1.1.2. This will use the following interface for eBGP.

int f0/0

ip vrf forwarding test

ip add 1.1.1.1 255.255.255.0

   address-family ipv4 vrf test

     neighbor 1.1.1.2 remote-as 20

     neighbor 1.1.1.2 ebgp-multihop 255

     neighbor 1.1.1.2 activate

HTH,

Regards

Kishore

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