VPLS across intermediate routers

[jturner2720]

I currently have a network doing both L2VPN and L3VPN between nodes, that all connect into a collapsed core.

So traffic might go site A -- PE -- P -- P -- PE -- site B.

My question is what do the P routers need to support? Do they need to understand the full VPLS stack to be able to forward the packets? Or is just understanding MPLS sufficient as they just need to be able to know what to do with the labels? Or even just simple IP as the intelligence is all on the PE end?

I'm wondering if say something like a Nexus 9500 might be a suitable box for this purpose? I know there used to be a design of having Nexus 7K at the core of a campus network, but those are going EoL so not a platform to invest in.

[rais]

At the minimum, P routers should know how to switch/distribute labels. 

HTH.

[Giuseppe Larosa]

Hello @jturner2720,

P nodes will do simple MPLS label swapping of the external label the one that changes at each MPLS node hop with destination remote PE loopback. They do not try to inspect the payload.

In the case of VPLS the source PE choices the exit PE based on MAC address learning it will choice the exit pseudowire as the one where the destination MAC address has been seen as source.

All the PEs taking part in a VPLS instance will emulate a single distributed L2 switch with "ports" Access links on each PE.

Depending on the type of VPLS implementation the pseudowire internal label can be provided by LDP or by MP BGP

Hope to help

Giuseppe