Configuring LDP on mpls enabled router

Question

I am trying to configure LDP on a mpls enabled router and I am using RIP as the underlying IGP. But the LDP neighborship is not coming up, when I replace RIP with OSPF it works fine. My question is can we use RIP or static routing while configuring LDP in a mpls enable router ? Most of the materials which I found on internet only talk about OSPF and IS-IS. Hence I am confused.

Answer 1

You are free to use any routing protocol, there is no relationship between the IGP and MPLS LDP, only between RIB content and LDP source, destination. Let say Router A try to establish LDP peering with router B.

It's peering establishment process is based on Hellos packets (basically UDP packets sent on well known "all routers on this link " multicast address with a port dedicated) TCP mechanisms.

Once Hellos have been exchanged, next steps will include:

• Transport layer establishment (TCP connection to make it simple).
• Session establishment where different parameters are negotiated.

This basically means you only need a valid IP path between initiator and it's peer. so RIP, OSPF, ISIS, static routing or even BGP are possible.

Basically if you are using loopback IP to establish your LDP neighborship, your 2 Loopback should be able to PING each other.

So I don't see a reason why RIP make the process to fail.

I suggest you share:

• your IP addresses config.
• your RIP config.
• your LDP config.
• PING attempt between the 2 LDP peers (based on loopback IP I suppose).