L2VPN tx and rx problem - no label in Provider router

[Amirmahdi.M]

Hi everyone

i was doing an l2vpn test in my eve-ng lab but the layer 2 connectivity between my CE routers had a problem.

i looked into the problem with wireshark and realized that arp goes from CE1 to CE2 but in the way back it gets dropped in the P router.

when i do a show mpls l2 vc nothing seems wrong but when i do a show mpls forwarding-table this is the result:

P#show mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or Tunnel Id Switched interface
16 Pop Label 2.2.2.2/32 82392 Gi2 172.16.2.1
17 No Label 1.1.1.1/32 44388 Gi1 172.16.1.1

as far as i know there shouldnt be a No Label prefix in the mpls forwarding-table of a P router that connects to PE Router.

This is my Topology:

CE1 - PE1 (service instance xconnect to 2.2.2.2) - P - PE1 (service instance xconnect to 1.1.1.1) - CE2

the running config of the PE1,PE2 and P router are attached.

this is the eve-ng topology (dont mind the extra links betweeb PE and CE)

i think that there is a problem in the forwarding-table of P router. i'd be pleased if anyone can help me resolved this problem.

[Harold Ritter · Accepted solution]

Hi @Amirmahdi.M ,

The issue is that you configured the loopback interface IP address on PE1 as a /24 rather than a /32.

The default network type for a loopback interface in ospf is "loopback", which means that ospf will advertise it as a /32, regardless of the configured subnet mask. The default can be changed with the "ip ospf network point-to-point" command, but it is generally recommended to keep the default setting.

ldp on the other end will advertise the label binding for the loopback interface as a /24. As there is no match between the ldp label binding and the ospf route, the label binding received from PE1 on P will not be used, hence the "no label" condition.

It is generally recommended to configure the loopback interface ip address as a /32.

This should fix the issue you are seeing.

Regards,

[MHM Cisco World]

You need 

Mpls ldp router-id lo foreced<<- this for ios

Then use this router-id in l2vpn