Fabric Extend over ISP (Hub-and-spoke)

[bfaltys]

We have our own fiber mesh and SPBM running fine. We are getting additional links at multiple sites from an ISP. The ISP is using q-in-q so we basically have a pseudowire from the core to each site. Since we cannot map our 2 BVLANs to multiple ISP tags we need to use layer 3 fabric extend, as far as I understand. It seems like this is possible, but I haven’t been able to locate a good example yet. Am I thinking about this wrong? Would this require our interface to the ISP at both ends to be a layer 3, routed interface? Would we need a separate /30 between the core and each site? I’m sure I have more questions, but this would be a good start.

[Miguel-Angel_RO]

That’s indeed the case. Multiple logical interfaces on one physical interface.

The MTU should be at least 1544.

Mig

[bfaltys]

So we need a separate pair of transport vlans per logical interface/per site? Can multiple logical interfaces use the same physical interface (I assume that should be ok).

[Miguel-Angel_RO · Accepted solution]

Hi bfaltys,

L3 interfaces are not needed.

Here from the doc:

Mig

[bfaltys]

This image just shows one “spoke” site.