[ovs-discuss] packets not being forwarded beyond 65 hops of

[Flavio Leitner]

On Thu, Aug 14, 2014 at 10:01:56AM -0700, Ben Pfaff wrote:
> On Wed, Aug 13, 2014 at 6:57 PM, Flavio Leitner <fbl at redhat.com> wrote:
> > If it's kernel DP, then patch ports are internal ports which during TX
> > inserts the packet (skb) into the CPU backlog queue (enqueue_to_backlog())
> > for later processing.  Later on, the backlog queue is processed
> > (process_backlog()) and the packet is actually received by the other port.
> 
> I missed that we're talking about patch ports.  That explains the whole issue.
> 
> Patch ports are implemented in userspace regardless of the datapath in use.
> They do not exist as ports visible from the kernel (definitely not as internal
> ports).  Hops across patch ports are "optimized out" in userspace, but the
> recursion is limited to 64 levels, hence the issue you're seeing.
> 

Hm, so "optimized out" in userspace means that in the kernel datapath
the ports don't exist but the connection is there, got it.

Thanks,
fbl