It's true that pyswitch does install flows with a timeout. However, there's another reason as well: NOX deletes all flows on a switch when the switch connects (in builtin/nox.cc).
If it didn't, it's difficult to reason about what installing a particular flow would actually do (e.g., possibly nothing). That said, I've wondered for a while whether this should actually be an option, so that a clever application COULD actually inspect the flow table on switch connect and decide what to do... -- Murphy On Mar 24, 2011, at 7:51 AM, Christian Esteve Rothenberg wrote: > Harry, > > the problem is that the datapath flows do expire after 5 seconds of > inactivity. You can change this in the pyswitch flow install timeout options. > You can also check that if you keep sending ping packets between the hosts, > the flow entries do not expire independent from the controller connectivity > (unless you opt to change the default behaviour of switches after loosing the > connection to the controller). > > -Christian > > > > On Thu, Mar 24, 2011 at 11:28, Harry <[email protected]> wrote: > Hi all, > Anyone could clear me this issue: > I'm playing with the pyswitch component built on NOX. I start a single switch > (ovsk switch) network in mininet with 3 hosts (h2,h3,h4), then start NOX > controller with pyswitch. > I ping from h2 to h3, log messages show that the controller successfully > installed datapath flow for the first 3 packets (ARP & ICMP) between h2 & h3. > Then I exit the controller, of course, I still ping from h2 to h3 (because > datapath flows have been installed on the switch). > But when I restart the controller and do the ping h2->h3 again, why does the > controller reinstall the datapath flows on the switch? The datapath flows on > the switch seem to be cleared when I restart the controller. > > Thank you very much! > > _______________________________________________ > nox-dev mailing list > [email protected] > http://noxrepo.org/mailman/listinfo/nox-dev > > > > > -- > Christian > _______________________________________________ > nox-dev mailing list > [email protected] > http://noxrepo.org/mailman/listinfo/nox-dev
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