On Jul 14, 2013, at 4:51 PM, Joseph D. Beshay wrote: > I have been experimenting with Mininet for some time and I noticed that not > all packets that do not match a flow entry are being forwarded to the > controller. > > I have a UDP stream from a host to another across a linear topology of 5 > switches. While changing the rules on the switches, I expect some packets not > to find a matching rule on one or more switces. However the number of packets > the receiver reports lost is always greater than the total number of packets > the switches send to the controller (i.e. The receiver loses 70-80 packets > while only 20-30 packets are sent to the controller).
With five switches and without knowing the nature of how you're changing the rules, I couldn't swear you're not losing some for reasons which make sense even if every packet was sent to the controller. But you may also be running into Open vSwitch's rate limiting behavior. Look up controller_rate_limit and controller_burst_limit in the ovs-vswitchd.conf.db man page. You could try either adjusting those, switching to the reference switch (which as far as I can remember doesn't have any rate limiting), or possibly installing a low-priority catch-all rule with an explicit send-to-controller action. > According to the OpenFlow specs, aren't switches supposed to forward all > table misses to the controller? Is there something obvious I am missing here? I'd say it's sort of assumed in the 1.0 spec. Practically, it's an easy way to get the control channel totally saturated. If I recall, there was a proposal to specifically add rate limiting, though I don't know what (if anything) happened to it. I think more than one switch implements it anyway. -- Murphy _______________________________________________ openflow-discuss mailing list openflow-discuss@lists.stanford.edu https://mailman.stanford.edu/mailman/listinfo/openflow-discuss
