I have a router, R1, that is serving as a default gateway on a network segment. Let's say port eth0 has an ip of and is connected to a switch, S1.

Another port on the router, eth1, is part of a VPLS running over an MPLS network. I would like to connect to other end of the VPLS network to S1, so that the network clients on the other end of the tunnel can use R1 as a default gateway, so the setup looks like this:

  • Port eth0 of R1 connected to S1
  • Port eth1 (VPLS port) connected to S1
  • Other clients connected to S1 can use R1 as default gateway and communicate with clients on the other end of the tunnel

But when I do so, I get large amounts of TCP retransmissions and duplicate ACKs when clients from the other end of the tunnel tries to route through R1, and performance is obivously very low.

What am I missing? Is it simply not possible to do something like this, where R1 is both a default gateway, and provides the VPLS interface? Will I need to use another router to terminate the VPLS connections?

I should note that the VPLS tunnel itself is working as expected, as is any client that is connected directly to S1 and using R1 as a gateway. It is only when R1 is connected to S1 both via the normal interface and the VPLS interface that things go awry.

  • Can you post your configuration?
    – Ron Trunk
    Apr 10, 2016 at 21:30


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