MPLS CE to CE not pinging

[Abdul Mateen]

Hello,

I am unable to ping loopback from one CE (SCB-LHR) to other CE (SCB-ISB) despite i received the loopback in routing table of corresponding remote CE's in my GNS3 topology.

1- OSPF is running in MPLS Domain

2- MPLS is configured properly

3-VRF's are configured properly with RD and RT and association of ports done as well.

4- MP-BGP is running normally

5- PE-CE routing is conducted as well
6- Redistribution is performed as per the standard.

Below are the snipp of show ip route details.

[lespejel]

hello @Abdul Mateen

what about ip mpls feature? is it enabled?

you have to check CEF to verify what interface/label is assigned to forwarding, I see routing works (control plane) but that's BGP and IP inside MPLS cloud, now verify forwarding plane, you must find labels into PE routers associated to PE's BGP neighbors.

[Abdul Mateen]

I have checked MPLS peering are normal. Each PE router has two neighbors ( one Core Router & one PE) as shown below

Also as per below mpls is enabled only on that interfaces which are under mpls domain. 

[a.alekseev]

you'd better share the configs...

[Abdul Mateen]

[Harold Ritter]

Have you tried pinging from one CE to another, specifying the source address, which should be set to the loopback interface ip address?

Regards,

[Abdul Mateen]

Yes I tried pinging CE to CE from source loopback address but its not
pinging.

[Abdul Mateen]

CE to CE Ping with source loopback 

[Abdul Mateen]

Attached are the running config files of the shared topology,

[a.alekseev · Accepted solution]

always use /32 mask for your mpls loopbacks

[Abdul Mateen]

I changed mpls loopback to /32 and issue resolved. 

But i want to know what it really matters for /32 or whatever subnet used for loopback

[a.alekseev]

in cisco implementation, ldp advertises labels for all igp prefixes and for loopback too

although by default ospf advertises  loopbacks always with /32 mask, no matter which real mask is.

You can change this behaviour for ospf by adding "ip ospf network point-to-point" to your loopbacks configuration.

[Abdul Mateen]

@ a.alekseev Thanks for sharing your valuable feedback.

Can you please also explain whats the behavior difference between /24 and /32 for loopback peering withing MPLS domain

[a.alekseev]

try ping a.a.a.a source lo0

and show from PE's

"sh mpls forwarding-table"