On 01/19/15 at 09:58am, Ben Pfaff wrote: > To keep the discussion going, let's talk about each of those features. > > These days, OVS allows an ARP responder can be implemented in the > OpenFlow flow table (since all ARP fields are modifiable), but that has > only been true for a few versions. Before that, an ARP responder could > only be implemented in an OpenFlow controller. So to support those > older versions, OVN would have to detect support for ARP field > modification and divert packets to ovn-controller. I think > ovn-controller will probably need a general framework for that kind of > thing, so it's probably feasible.
Do you have something specific in mind already on how to test availability, in particular for existing OVS releases? Configuring a dummy flow table with certain matches and actions on startup and constructing a list of capabilities based on it? For new releases, a new OVSDB could provide capabilities. > But maybe by "ARP responder" you don't mean the ability to respond to > ARP requests but the ability to synthesize ARP requests from IP packets, > like a router needs to do. OVN will have to do this to implement L3 > features. No current version of OVS can do this from the flow table, so > it will have to be implemented by ovn-controller diversion everywhere. > This may be acceptable, because ARP isn't that performance sensitive, > but perhaps we'll find out that there's good reason to build it into > OVS. Then we'd, again, make OVN probe for support and use one strategy > or the other. Another minor difference to be taken care of is the capability of implementing certain set-fields in the datapath. An example right now would be ARP fields which require a user space fall back. > Conntrack, on the other hand, is a feature that doesn't have a > reasonable implementation without datapath support. Without it, OVN > would have to fall back to simple TCP flags matching on OVS that > supports that, or skip the firewall entirely on OVS that doesn't have > it. _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
