LDP or TDP?

[NAVIN PARWAL]

Folks,

I have a MPLS network setup in my lab. I have MPLS Layer3 VPN configured and running. Now, I am reading about Layer-2 VNPS ( EoMPLS) and one of the requirements is to use LDP instead the default TDP for label distribution. My question is if Layer-3 and Layer-2 VPNs can coexist together, what should i use?????

Thanks

[Harold Ritter]

A couple of things. The protocol used to learn the IGP label (often referred to as the outter label), which can be TDP or LDP (or RSVP if TE is configured between the PEs). The purpose of this label is to get traffic from the ingress to egress PE.

The protocol used to learn the VC label (often referred to as the service or inner label), which can only be LDP in the case of L2VPN. A targetted LDP session is brought up automatically when you configure the "xconnect x.x.x.x" command on the PEs. The service label is used to demultiplex the traffic on the egress PE.

Note that in the case of L3VPN, BGP is used to learn the service label.

L3VPN and L2VPN will coexist regardless whether LDP or TDP is used in the core for the purpose of learning the IGP labels.

Let me know if I answered your questions,

[NAVIN PARWAL]

Right now, I am only doing L3 VPN, so i am running TDP which is the default.

I also want to do L2vpn now using metro switches (EoMPLS), same config on CCO says use LDP.

So basically when i configure LDP , TDP will no longer be the default label distribution protocol right?

and i will be using LDP alone with TDP? and this will not effect my L3 VPN??

Thanks

[Harold Ritter]

You can certainly continue to run TDP in the core for the purpose of exchanging IGP labels, which is required for both L2VPN and L3VPN.

The fact of configuring EoMPLS doesn't change your default label distribution protocol.

As stated in my previous posting, you don't need to configure LDP explicitly for EoMPLS since it will be done automatically when configuring the xconnect command. TDP can still be your default protocol at that point.

Again, if you don't change your default label protocol, TDP would be used for for IGP label distribution. LDP is used for EoMPLS VC label exchange and BGP for VPN label exchange (L3VPN).

I would probably migrate to LDP in the core though as it minimizes the number of protocol needed.

Let me know if I answered your questions,