[ovs-discuss] Adding VLAN tag to GRE Tunnel Header

[Ben Pfaff]

On Tue, Oct 01, 2013 at 02:18:33PM +0000, Kevan McColgan wrote:
> We have a GRE tunnel between 2 ovs instances. We are trying to add a
> vlan tag to the GRE tunnel header.
> 
> We are using this opeflow definition:
> ovs-ofctl add-flow br-tunnel in_port=1,actions=output:2,mod_vlan_id:15

That command doesn't make any sense.  It does header modifications but
never subsequently sends the packet anywhere, so of course the header
modifications don't take effect.

> However, the vlan tag of 15 is not being added to the GRE header. Can
> anyone shed some light on if we are missing some config?

You'll have to do this after the tunnel encapsulates the packet.  If the
tunnel's output is routed through a second OVS bridge, then you could do
it there; otherwise, iptables might be able to do this (I don't know).