[ovs-dev] [PATCH] ovn: Support ARP proxy in logical switches.

Han Zhou zhouhan at gmail.com
Tue Jan 10 00:08:08 UTC 2017

Hi Bruce,

This feature is useful for me. I had the concern because the use case for
me is intermediate. It is for k8s integration. In k8s there is a kubeproxy
running on each host to do service-ip NATting, and I am using OVS
(programmed by OVN) to connect host network namespace to containers (and
also connection between containers on the same host). When an NATted
end-point of a service-ip happen to be on the same host (and of course,
same L2, since we use bridged mode), then the return traffic would be
forwarded directly to the source without going through the kubeproxy. With
this ARP-proxy patch, the interface to the host network namespace is
specified as ARP proxy port, and traffic between containers will go through
the host for NATting.

This is an intermediate solution because a better way to do it is to
utilize the load-balancing feature of OVN to replace kubeproxy completely,
and the problem won't exist at all. It just takes more effort to integrate
and we are not there yet.

Hope this clarifies my use case. But I'd like to hear if this feature would
useful in any other circumstances.


On Mon, Jan 9, 2017 at 2:57 PM, Bruce Davie <bdavie at vmware.com> wrote:
> Han,
> Your comment gave me pause:
> > I have similar concerns about how useful it is.
> Whereas the current proxy ARP function in OVN has a pretty clear
motivation & tightly defined use case (to avoid needless broadcast of ARP
requests across the overlay when the logical router’s IP and MAC are known)
it seems like even you don’t really have a clear use case in mind for this
additional functionality. Can you try to lay our more clearly why you think
this is a useful enough addition to OVN to warrant the extra complexity?
> Thanks
> Bruce

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