Header Only - DO NOT REMOVE - Extreme Networks

stpd and qinq

Whats the proper way to handle loops with qinq.

We have 2 feeds from a customer's core to a bunch of remote sites, we will be running the vman to all the sites back to our core, our core is 2 sets of 2 mlag'd x670's...

On our aggregation layer we're between extreme and extreme on our own network, so we will just add the vman tagged to our existing ISC and ports on both switches like a normal vlan...

But exiting to the customer we're untagging the vman to return it to standard vlans for them... Do they aren't using lag we're connecting to 2 separate switches and they are supposedly running stpd on their side...

Do I need to add the vman to the ISC? even though i'm handing off direct no lacp/lag to them, how do I make sure not to create a loop, I can't enable stpd towards them, as you cant run stpd on a vman only on a vlan...

pardon my crude ascii mockup 🙂

VARIOUS CLIENT EQUIPMENT delivered to their core via vman

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they say they are running stpd here on their vlans

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Do I just need to trust them to be running spanning tree and not create a loop, or how are others handling this.

1 reply

Userlevel 6
Hey Chris

So you are connecting two of your edge switches to their network and assuming they are running STP on their network to see a loop correct?

Is your intent to provide primary and back up services with your two switches? I am assuming so since they are supposed to be blocking one of the links.

I think you are correct that you cant do STP because the BPDU will not map to their networks. One option may be ELRP. Unlike STP it is an extreme protocol so it will go out untagged and should be passed by their equipment as they don't understand the protocol thus they will not try and process it. As long as the untagged VLAN spans both switches that should work. Another option is to look at ESRP. ESRP allows you to block L2 between the two extreme without sending anything to the customer. It could be a little more tricking but this setup doens't sound to complicated and so the config should be real easy.

Look up those two options in the User guide and let us know if you have any questions. Of course you should test this in a lab as I am not sure the exact configuration.

Hope this helps