Why can't VLAN tags be assigned to a GRE interface?

RouterOS Beginner Basics
1

Hi all,

I’m curious why VLAN tags can’t be assigned to a GRE interface. What’s the proper way to do this?

I’m doing it using EoIP but there must be away to send VLAN’d traffic over a GRE tunnel, right?

Thanks

2
  • bump *
3

No, there is no way as GRE transports Layer3 while EoIP is Layer2.

4

face palm

Its kind of obvious now you mention it, thanks

5

I can’t add VLAN tags to an L2TP interface either, so what’s the recommend way to bridge VLAN’s over a WAN?

I’m aware EoIP works, but ideally I’d like to use an ‘open’ protocol.

6

Well, if the ethernet frame already has the VLAN tag attached elsewhere, then L2TP will encapsulate that.
(what’s in the box stays in the box)

It’s basically that L2TP (just like GRE) is not ethernet, so an ethernet header on a protocol that’s not ethernet has no meaning. That would be like putting tires on a boat or a propeller on the hood of a car or something.

So if your L2TP profile is set up to bridge things, then make sure the vlan tag is present on the bridge, and that should carry across the way you want.

7

Thanks. I solved the mystery using BCP + L2TP

http://wiki.mikrotik.com/wiki/Manual:BCP_bridging_(PPP_tunnel_bridging)#BCP_Configuration_.28CLI.29

8

Grats! (I guess I recommended this without knowing there was a wiki page calling it BCP bridging - heh)

9

I attempted to add the L2TP interface to the bridge and it failed, so a little bit of Googling revealed BCP which worked as planned.

Thanks again for the nudge in the right direction