On Tue, Dec 01, 2015 at 11:44:49AM -0800, Han Zhou wrote: > On Tue, Dec 1, 2015 at 10:34 AM, Ben Pfaff <b...@ovn.org> wrote: > > On Mon, Nov 30, 2015 at 11:02:29PM -0800, Han Zhou wrote: > >> Hi Ben, > >> > >> On Tue, Nov 24, 2015 at 6:12 PM, Ben Pfaff <b...@ovn.org> wrote: > >> > I'm having trouble figuring out which one we should do. The reason that > >> > I'm torn between choices is because of layering. I like the way that, > >> > currently, the switch and router datapaths are (almost) independent of > >> > each other, in the sense that they don't have to know anything about > >> > what they're attached to. However, we've already got one violation of > >> > this principle: logical routers statically discover MAC-IP bindings on > >> > their attached switches. For now, that's pretty much necessary, since > >> > logical routers don't support ARP yet (I'm fixing that, don't worry), > >> > >> By "support ARP" do you mean logical routers broadcast ARP requests to > >> lswitch ports and then process ARP replies (from the owner of the IP) > >> to get IP-MAC bindings? > >> In such case even if this kind of dynamic ARP is supported, it would > >> still be valuable to continue supporting the static MAC-IP bindings, > >> which is the major scenario of CMS such as openstack, where IP-MAC > >> binding is known during VM provisioning (and similar use case for > >> containers). I think dynamic ARP introduce higher costs, and requires > >> periodical refreshing, so it is better to be triggered only when > >> static binding is not available. > >> > >> Or do you mean any other kind of ARP support? > > > > I do mean what you thought. ARP is more or less necessary because > > IP-MAC bindings aren't always statically available, especially when > > physical infrastructure is brought into a logical network. > > > > I don't think we'd ever discontinue the static MAP-IP bindings. They > > are a valuable optimization. If we decide that strict layering is > > important, then they could be implemented by having logical routers send > > out ARP requests and then having the logical switches send the ARP > > replies. The ARP would never travel over a physical network in this > > case. > > This clarified my confusion. While this option implements strict > layering, it still introduces unnecessary stages (ARP request/reply) > for static MAC-IP bindings because in that case ARP should be > considered as already resolved in the beginning.
Yes, I wouldn't be happy with that either. > > However, as we continue our discussion here, I'm leaning more and more > > against worrying about layering issues, at least in the current context. > > > > I have the same view at this point. Please let me know if I should > continue the patch to remove the redundant MAC field. I think it's worthwhile, please give it a shot. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
