topic Re: Add fabric extend to current mesh in ExtremeSwitching (VSP/Fabric Engine)

Add fabric extend to current mesh

bfaltys — Fri, 03 Sep 2021 21:36:24 GMT

This will build on something I posted about a while back, but the situation is this:

-we have a fabric built across the city with our own owned fiber

-we are getting additional, redundant links from an ISP

-we want to use the ISP links to add to our fabric

-we have 2 test sites up. One is only connected to the ISP and the fabric extend is working. the other site is connected to the ISP and our original fabric. In the second case, the link over the ISP shows “INIT” for the IS-IS adjacency. Is it possible to have full adjacency over the ISP and our original fabric at the same time?

-For the fabric extend, I am using brouter ports and I have loopback IP as tunnel source & destination. Both of these are running OSPF so that I don’t have to build a bunch of static routes going forward. I also added OSPF redistribution into IS-IS.

I can add configs/diagrams, but wanted to throw out some facts and the question.

Re: Add fabric extend to current mesh

bfaltys — Fri, 03 Sep 2021 22:08:23 GMT

One update, I built this out in a lab. Without redistributing OSPF into ISIS...If I remove the direct link the primary adjacency goes down and the fabric extend adjacency comes up. So, what can I do to have both adjacencies at the same time?

Re: Add fabric extend to current mesh

bfaltys — Sat, 04 Sep 2021 01:52:24 GMT

Another update: This works if I use a separate VRF for the links over the ISP. Not sure on the technical details of why this works.

Re: Add fabric extend to current mesh

Roger_Lapuh — Mon, 06 Sep 2021 14:31:23 GMT

Yes, you can have Physical and Logical NNIs in your setup. This is perfectly fine.

What I assume is happening in your setup is that your underlay FE routes are learnt through an NNI. This has to be avoided as we cannot run FE over MACinMAC.

You can either:

use a separate (non-IS-IS)VRF for your underlay as you have done. This will ensure FE underlay routes are never learnt through IS-IS.
if you use the same routing table for your FE underlay as well as your IS-IS routed traffic, then you will have to configure a route policy ensuring that your FE underlay routes are not learnt through IS-IS.

Makes sense?

Roger

Re: Add fabric extend to current mesh

bfaltys — Tue, 07 Sep 2021 19:44:16 GMT

That makes sense. What I ran into on Friday is that with 2 test sites, only 1 of the 2 will be up. They are on different brouter ports in the same VRF (not the GRT). Each link is a different 172.x.x.x/24 subnet with routes to the peer’s loopback. The VLAN on the brouter ports is different for each link. Feels so close to being done!

One example given to me uses VLAN interfaces instead of brouter ports, but to me that should not make a big difference as long as the devices have routes to the tunnel destination.

Re: Add fabric extend to current mesh

bfaltys — Tue, 07 Sep 2021 19:48:42 GMT

Looking back at some notes from when I labbed this up and I used brouter ports with 2 subnets and different VLANs on the brouter ports….both peers came up in that scenario.

Also, when I run “show isis logical-interface” it shows the 2 tunnel interfaces, but lists the same physical port and vlan even though they are configured differently.

So the down site should be port 1/48 vlan 2802. That brouter is 172.31.255.3/24. I can’t figure out what it is looking out the wrong port.

Re: Add fabric extend to current mesh

bfaltys — Tue, 07 Sep 2021 20:12:14 GMT

I believe I have figured this out. I had the same OSPF router-id configured on the 2 edge sites. That makes sense then...Once I fixed that, both isis adjacencies came up and have stayed up.

Re: Add fabric extend to current mesh

Roger_Lapuh — Tue, 07 Sep 2021 20:38:14 GMT

thanks for letting us know!

Roger