[ovs-discuss] Create GRE/VXLAN Tunnel between VM'S using virtual interfaces

Scott Lowe scott.lowe at scottlowe.org
Thu Jun 15 21:20:10 UTC 2017

On 06/15/2017 01:41 PM, Phaniprakash Jayanthi wrote:
> Hello everyone, 
> I have configured the following topology on a single host machine as
> described below:
> I have created 3 VM'S & 2 ovs bridges in this topology. VM1, ovs-br1,
> vm2, ovs-br2, vm3 are connected serially. 
> VM1 --- ovs-br1 ---- VM2 --- ovs-br2 ---- VM3
> VM2 acts as a router. VM1 and VM3 are in different subnets. I want
> packets sent from VM1 to VM3 to be GRE/VXLAN encapsulated when the
> packets leave ovs-br1 and decapsulated when they leave ovs-br2. I do not
> want to use any physical ethernet ports as the tunnel
> endpoints/remote_ip's. I am trying to use the IP addresses configured to
> the two ports of VM2 as endpoints but it does not seem to work. Can
> anyone help me out with this idea? I would like to discuss how to
> configure my ovs-bridges for this idea. Your ideas are really appreciated.

This is a topic that has come up a few times, and (so far) there haven't
been any useful answers.

In thinking about this, it's possible you could use OVS internal ports
on ovs-br1 and ovs-br2. (These would act as the IP endpoints that the
GRE/VXLAN tunnel needs.) Put these internal ports on the appropriate
subnets, and ensure the host (where all this is running) has routes to
the subnets (which I assume would mean pointing the routes to interfaces
on VM2). Then configure tunnel ports pointing to the IPs assigned to the
internal ports (ovs-br1's tunnel port would point to ovs-br2's internal
port and vice versa).

It's just a guess, and I don't have time to try out the configuration
myself, but it just might work.


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