We are moving to a new L2 fiber network and i'm having trouble figuring out how to connect the DR. We are using a spoke and hub topology, with HQ as the hub. The branch locations all have unique networks and my plan is to use L3 switches to route traffic between them. The exception is our DR site. It runs the same network as HQ and currently uses an L2 link to connect. DR doesn't know its thousands of miles from HQ from a networking perspective. The new equipment for the fiber network only gives me one port to connect branches and DR. Is it possible to connect to DR over an L2 link like we do now, AND to the branches over an L3 link on the same interface? I hope this makes some sense.... Thanks for any help.

network diagram

  • 1
    Well to give a more correct answer, a drawing would be nice with equipment placements and distance to your branches and DR.
    – user36472
    Commented Dec 13, 2017 at 19:05
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer.
    – Ron Maupin
    Commented Feb 19, 2018 at 20:35

2 Answers 2


Does the "L2 fiber network" support VLAN trunking? If so, it's probably the best solution to use multiple VLANs to separate the traffic within a single, physical link.

That way, you can run mixed L3 and L2 connections with as many or as few links as you like. Feel free to add details about your setup to your question (network layout, diagram, addresses, ...) and I'll expand the answer.

If no VLAN tagging is supported you need to set tunnels for the required, additional connections.

edit: Routed links (L3) don't require separate VLANs. Depending on security or architecture requirements, you could route all of them through a single VLAN including the untagged one. I'd use one VLAN to bunch all the router interfaces together.

  • Diagram added. I believe VLAN tags will be honored, but i will have to verify. So would each L3 network be in its own vlan? Would the network spanning the L2 link need to be in a vlan as well? or would it just be the native network on the link?
    – TheGewp
    Commented Dec 14, 2017 at 22:43

An 802.1q trunk would be a way to accomplish this if supported.

  • 3
    Generally a possible approach but you should be more specific.
    – Zac67
    Commented Dec 14, 2017 at 7:34

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