[a-nsp] Terminating a Q-in-Q L3 interface?

[Tyler Conrad]

Hey Bryan,

Have you already looked through the flexencap TOI?

https://www.arista.com/en/support/toi/eos-4-24-2f/14551-flexible-interface-encapsulation-flexencap


On Fri, May 10, 2024 at 09:19 Bryan Holloway via arista-nsp <
arista-nsp at puck.nether.net> wrote:

> So in Cisco (IOSXR)-land, it's trivial to terminate double-tagged
> traffic on an SVI like so:
>
> interface Bundle-Ether3.900
>   ipv4 address 10.11.12.13 255.255.255.252
>   encapsulation dot1q 900 second-dot1q 100
>
> ... where 900 is the outer-tag, and 100 is the inner-tag.
>
> I've been trying to figure out a way to do this on Arista.
>
> Since there's no built-in way to do it on standard SVIs, I thought I'd
> take a look at their double-tag VLAN translation feature, which looks
> like it'll do the trick.
>
> So I created the following:
>
> interface Ethernet49/1
>     switchport trunk allowed vlan 900
>     switchport mode trunk
>     switchport vlan translation 900 inner 100 200
>
> ... which purports to dump double-tagged 900:100 traffic into the VLAN
> 200 bridge domain.
>
> To wit:
>
> "On ingress, specified double-tagged packets are mapped to the bridging
> VLAN, and on egress packets with the ID of the bridging VLAN are double
> tagged as specified."
>
> So I created VLAN 200 and an SVI:
>
> interface Vlan200
>     ip address 10.11.12.14/30
>
> But it doesn't work. Notably, the SVI doesn't even come up because there
> are no interfaces using VLAN 200.
>
> Fine ... so I added 200 to another unrelated trunk, which caused my
> VLAN200 interface to come up.
>
> But still no joy. I know this is a bit kludge-y, but shouldn't it work
> as advertised?
>
> Has anyone succeeded in something like this? I'm open to suggestions,
> thank you!
>
>                 - bryan
>
> P.S.: Running 4.25.4M on the Arista, which is admittedly a little long
> in the tooth.
> --
> arista-nsp mailing list
> arista-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/arista-nsp
>
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