[ovs-discuss] Get rid of immortal ARP

Justin Pettit jpettit at ovn.org
Tue Sep 20 07:57:34 UTC 2016


> On Sep 20, 2016, at 2:34 AM, Warsang <warsang at minet.net> wrote:
> 
> Hello everyone, I am simulating a fat tree topology with ECMP. When one of my host sends an ARP request in broadcast, the packet is broadcasted through all switches which creates more and more traffic because I have no STP. My question is simple. What is the best way to get rid of these immortal packets? I thought of using something similar to a TTL header which would be decremented every time the packet hits a switch and dropped when it gets to zero however this method seems a bit too complicated to implement and I was wondering if there was a better, more simple way to do so using OVS?

I'm not sure what a TTL would look like in ARP, since it doesn't have such a field, and an L2 switch wouldn't normally decrement one even if there were.  Do you have enough visibility into the topology to program OVS to only forward broadcasts in such a way that they won't form loops?  I've seen some SDN applications do this to make better use of their links than can be achieved with STP.

--Justin





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