We're working with a metro ethernet provider to bring up a new multi-point connection between our sites. Currently we're just trying to get it working with two sites. As a simple test I've plugged in an HP switch at either end using an untagged, layer 3 addressed VLAN port.


  1. I can't ping between the devices on the new link
  2. I can ping between the devices using a known-good point-to-point ethernet link
  3. The provider claims that using testing equipment, the metro ethernet circuit passed all layer 2 connectivity tests.
    • This is an ethernet product from the provider so I assume that means the tests were layer 2 ethernet tests. I also asked questions about ethernet frame sizes, etc so I think it's a safe assumption.
  4. Wireshark traces show a provider-owned device firing off several 802.1ag "CFM" protocol, "continuity check messages". The provider confirmed this is their hand-off device (that my switch is plugged into) by MAC address.


  1. Assuming my metro ethernet circuit is implemented with VPLS, should I be seeing these messages (described in #4 above) from the provider equipment on my circuit or should these be "out-of-band" (therefore a configuration problem)?
  2. Assuming our metro ethernet circuit is implemented by VPLS, what would block layer 3 traffic but allow layer 2 connectivity?

1 Answer 1


This turned out to be an issue with the provider-side equipment. They swapped our physical hand-off port at one end to another and things started working. They said it was due to a damaged physical interface, even though layer 2 tests seemed fine(?).

So it seems like with these VPLS connections, it is possible to have layer 2 connectivity without layer 3 connectivity.

  • You should accept your answer so that the question doesn't keep popping up looking for an answer, forever.
    – Ron Maupin
    Commented Oct 19, 2015 at 16:27

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