[ovs-discuss] Proxy ARP

Lori Jakab lojakab at cisco.com
Mon Aug 25 10:34:18 UTC 2014


On 8/24/14 5:47 AM, David F. Sire wrote:
> Hi,
>
> I'm using LISP tunnels in Openvswitch and I read in REAME-lisp that if 
> "the VMs have IP addresses in the same subnet but the hypervisors are 
> separated by a router" in the network topology, we need an ARP proxy.

Can you give us more detail about what you are trying to do?  Unless you 
really really want to work on an ARP proxy internal to OVS, there may be 
other solutions.

For example, you could use /32 (v4) or /128 (v6) addresses in your VMs 
to avoid having two communicating hosts being in the same subnet and 
sending ARP requests if the first place.

Alternatively, if you use an external controller, or you have a static 
environment, you can implement an “ARP responder” with flow rules only, 
as is done by OpenStack:

https://wiki.openstack.org/wiki/Ovs-flow-logic#OVS_flows_logic_with_local_ARP_responder

You can find detailed examples in the following blog post, look for 
Table 105 - ARP responder:

http://dtucker.co.uk/hack/building-a-router-with-openvswitch.html

Let us know if this helps with your use case, or please describe what 
you’re trying to achieve.

HTH,
-Lori

>
> What i want to do is to add this proxy in the code.
>
> I have no idea how to do it.
>
> Any help will be appreciated.
>
> Thanks,
> David



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