[ovs-discuss] How to use Click with OVS

[Jesse Gross]

On Thu, Oct 13, 2011 at 3:00 AM, Hamid Farhadi
<hamid.farhadi.nsc at gmail.com> wrote:
> Hi
>
> I made a simple integration of Click router and OVS. when I receive a
> packet, I modify it with Click then pass it to OVS via an Internal port
> (Tap0) and then receive it from another port of OVS (i.e. Tap1) and modify
> it again using Click and send it out of the box:
>
> eth0 -> Click -> tap0 -> OVS -> tap1 -> Click -> eth0
>
> both taps are internal ports made by OVS. once I send a packet to eth0, the
> CPU goes up and system hangs down. I think there is a loop in system. as the
> config, I have only two taps connected to br0. I am using click kernel
> module.
> any help pls?

It does sound like you have a loop but it's pretty to debug without
actually seeing the setup.  OVS by itself has built-in loop prevention
for traffic that stays on the box, so I'm guessing that the loop is
being formed with something else on the network.  A normal switch will
have a self-forwarding check so it shouldn't form a loop by itself but
maybe you have two of these things on the network?