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Layer3 802.1ad interface

I'm trying to figure out how to create a Layer 3 q-in-q interface in Exos on a summit X440 switch.

I've opened a ticket with support but I'm not getting anywhere so if anyone in the community can help I'd appreciate it.

If I need special licensing, a newer firmware version, or even a different model switch I'm open ...but I'm looking to solve the problem with an EXOS solution. I do not want to buy more Cisco stuff. (I'm trying to get rid of the cisco stuff lol) It doesn't make me look good as a sales partner with Extreme to run a bunch of multi-vendor Cisco stuff to achieve our networking goals.

The details:

I need to create a logical interface on the switch within the CVID of a VMAN for inter-vlan routing of CVID's, in other words, double-tagged logical interfaces with L3 forwarding enabled.

With IOS I would do:

interface gi0/0.10403
encapsulation dot1q 10 second-dot1q 403
ip address X.X.X.X x.X.x.x

There you can see you would have an 802.1ad double tagged local virtual interface (sub interface I think cisco calls it).

I simply cannot figure out how to do this on XOS.

Maybe its the difference between a router OS and a switch OS. IDK.


9 replies

Userlevel 7
Hi John, welcome back to The Hub 🙂

This concept is called a VMAN in the EXOS world. Here's a couple of resources that I believe will set you off in the right direction:
I'm using VMANs today.

The problem is that VMAN's just pass L2 VLAN's from one destination port to another.

I need to create an IP interface in the customers VLAN on the switch passing the traffic for CVID routing.

Extreme Networks VMAN's consist of VMAN ID and within the VMAN ID it passes CVID's.

I need a L3 CVID interface in the VMAN on the switch.
Userlevel 7
Gotcha. Can you post a diagram of what you need? I'm told we should be able to make it work.

Fast diagram hope you're understanding my configuration with this.
Userlevel 7
Hi John,

as far as I know the IOS stacked VLAN routing example you gave works with Cisco routers only, not with switches. Switches usually support Q-in-Q only as a layer 2 mechanism (I have checked this for EXOS, (Extreme) EOS, Cisco IOS, and Arista EOS recently).

You might be able to use two EXOS devices, one to de-encapsulate Q-in-Q and another to implement routing, using VRs to separate layer 3 networks. But that does not scale, as you would need one cable (untagged port) per routing interface in general (i.e. with overlapping customer VLAN IDs).

Port specific VLAN IDs might help to get around the 1 port per layer 3 interface problem, but those cannot be combined with a layer 3 interface in the translated VLAN on the same switch, thus you still need at least two devices (I did not check the possibility of combining Q-in-Q and VLAN translation).

Best regards,
Hi Thanks for the reply. Thats what I've gathered exactly but I was hoping that maybe I was wrong. I'd like to use these switches as routers. Guess I'm stuck getting new ones instead.
Userlevel 6
VXLAN should work. But the x440 will not do it. You would need a x770 or a X670-G2 with 21.1.
Userlevel 7
From Extreme, there is just the S-Series able to provide layer 3 forwarding in a VXLAN, but even those switches do not provide layer 3 VXLAN interfaces, just VLAN interfaces.

Q-in-Q provides much better hardware support and less overhead (4 bytes instead of 50) than VXLAN. Software implementations (e.g. Cisco routers or a GNU/Linux host) provide practically unlimited scalability for layer 3 interfaces using stacked VLANs (interfaces matching on both S-Tag and C-Tag).