Hao, OVS doesnt need ARP -- its L3 forwarding that needs it.
When you ping, the kernel needs to know the destination MAC address that it needs to slap on to the packet. Unless it gets this the packet will not be forwarded. When it sends out the ARP request, OVS must forward it so that the other end can receive it and respond to it. If OVS is dropping the ARPs, then the other end will never receive it and the sender will never be able to send out the IP packet. You could try out by adding static ARPs. In that case, OVS with just the IP rules installed will be able to send out IP packets. Hope this helps. Thanks, Abhishek On Sat, Jul 18, 2015 at 10:04 AM, Justin Pettit <[email protected]> wrote: > > > On Jul 18, 2015, at 12:03 AM, Hao Wu <[email protected]> wrote: > > > > Hi, > > > > I'm curious that why OVS forwarding also needs arp? I find if I add a > flow in flow table as > "idle_timeout=0,ip,dst_scr=10.0.0.2,actions=output:2", the packets can't be > forwarded unless I also add the arp part: > "idle_timeout=0,arp,dst_scr=10.0.0.2,actions=output:2". For OVS, I think it > can work without the help of arp because it uses OF table which can match > IP part. > > ARP isn't IP--it has a different Ethertype--so you have to tell OVS to > forward it. > > --Justin > > > _______________________________________________ > discuss mailing list > [email protected] > http://openvswitch.org/mailman/listinfo/discuss >
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