I have two sites that I'm planning to interconnect via three circuits carrying layer 3.

They will be presented via fibre.

The bandwidth of the lines will be: 1Gbps, 1Gbps, and 2Gbps.

Each SFP will support 10Gbps.

Is it possible to create a port-channel with all three interfaces? Does the entire channel drop if one interface goes down?

  • Using port channels over long distances is problematic, and have different speeds on the links will certainly cause problems. Layer-2 across a WAN is really a bad idea, anyway. We live in a layer-3 world, and there is almost no reason not to use layer-3 for something like this.
    – Ron Maupin
    Dec 11, 2017 at 21:25
  • Thanks. Apologies, this will be layer 3. Allow me to change my question.
    – mbrownnyc
    Dec 11, 2017 at 21:28
  • Interface configurations, speeds and type has to be exactly the same, then it's possible.
    – user36472
    Dec 12, 2017 at 6:47

1 Answer 1


Layer 3 connections don't use STP; STP is used for deploying redundant L2 links. Port-channels also require layer 2 links, so that won't work.

Set up three routed links and use load balancing to distributed traffic. Load balancing can be done by IP addresses/ranges (easiest), services or actual link load (hardest). For each traffic group I'd set up one or two primary routes with the others as fallback and rotate that scheme across the traffic groups.

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