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How do I transport multiple VLAN trunks over the same physical link?

  I've got a microwave ethernet network that connects 7 different sites around our city in a ring-like topology. Each site has two microwave antennas and transceivers to implement the ring. Presently we are using industrial Moxa switches at each microwave tower site... these Moxa switches have a feature that normally flows traffic in one direction around the "ring" and can tell if one microwave link fails, then these switches will send the traffic the opposite direction so that all sites stay connected if one microwave unit fails. Presently I am not using any 802.1Q VLANs on this network because the minute I try to connect any one Cisco Catalyst switch port utilizing VLANs to a port on one of these Moxa switches, all 7 of the Moxas suddenly go into some kind of STP loop/storm and flash all their port LEDs in unison at a rapid rate, and all traffic ceases flowing thru them. I have come to the conclusion that the 802.1Q protocol implemented in their firmware is just simply 100% incompatible with Cisco's implementation for whatever reason.

I now have a request from management to be able to transport not only one 802.1Q trunk around this microwave "ring", but at least two different 802.1Q trunks which are completely different networks and there exists numerous VLAN ID number "collisions" between these two trunks.... in other words, there are not globally unique VLAN IDs.

I guess I need to replace all these Moxa switches with something else that can handle this new demand.

A simplified description of what I need is that I have one physical ethernet link system that I need to use to transport 2 or more simultaneous "logical" ethernet networks (each with its own 802.1Q trunk and set of VLANs) in a manner such that each logical ethernet network will not see, nor even be able to detect the existance of any others that are riding along upon the same physical link.

And I need to be able to do this on a shoestring budget.

How should I approach this problem?

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How do I transport multiple VLAN trunks over the same physical l


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How do I transport multiple VLAN trunks over the same physical l

Been looking into Q-in-Q. It seems that you have to reconfigure your switches to use (at minimum) 1504 byte MTU.

My entire microwave system does not support larger ethernet frame sizes. Some of its ethernet interface components have a hard max MTU of 1500.

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