Hi Martin, I am probably not fully appreciating the problem at hand too. My personal experience is that installing flow entries in the reverse direction (destination to source) and checking if a port is internal before updating host location goes a long time against such race conditions. To some extent, hop-by-hop routing simply slows down the entire process to remove the race conditions.
I do not have a good feel of how often this is the case of other deployments, but hop-by-hop routing does not seems like a good default for NOX to be in unless majority of the users needs it that way, which I would contend not. Regards KK On 24 February 2010 14:12, Martin Casado <[email protected]> wrote: > Again, I may not be remembering correctly, but things are complex if you > have multiple OF switches connected to a single non-OF switch. You can get > timeouts which create wierdnesses such as hosts attached to internal ports > (causing a software flood since the location is unknown). Hop-by-hop > simplifies the forwarding logic so you're reasonably assured that packet > processing will be done on the fast path. >> >> Hi Martin, >> >> I do not understand. This should not make a difference, since routing >> still have calculate a route, for which some OpenFlow switches might >> be connected directly. Doing it hop-by-hop does not make a >> difference. What am I missing here? >> >> Regards >> KK >> >> On 24 February 2010 13:58, Martin Casado <[email protected]> wrote: >> >>> >>> I believe it is simpler integration with a legacy network in which all >>> switches are not running OF. >>> >>> >>>> >>>> Hi, >>>> >>>> What is the motivation for hop-by-hop routing? Does seems novel in >>>> some aspects. >>>> >>>> Regards >>>> KK >>>> >>>> On 24 February 2010 13:52, Martin Casado <[email protected]> wrote: >>>> >>>> >>>>> >>>>> From Natasha: >>>>> >>>>> "I'm wondering if maybe the server is showing up on hpsw3, and so the >>>>> packet >>>>> is first getting routed there, and then re-routed again when it reaches >>>>> hpsw1. This is probably a result of all the authenticator code >>>>> commented >>>>> out >>>>> that was making it depend on routing. It's in a couple places >>>>> (wherever >>>>> the >>>>> word "routing" is used)." >>>>> >>>>> This is likely the culprit. Currently Nox 0.6 is doing hop-by-hop >>>>> routing >>>>> rather then setting up the full path. Can you search for routing_mode >>>>> in >>>>> authenticator.hh, authenticator_modify.cc and authenticator_util.cc, >>>>> uncomment the code and see if this fixes the problem? >>>>> >>>>> >>>>> >>>>>> >>>>>> I notice that the routing module is behaving differently with NOX0.6 >>>>>> causing each switch en route to generate independent packet_ins, while >>>>>> NOX0.4 generates only 1 packet_in. This behavior incurs higher flow >>>>>> setup time. >>>>>> >>>>>> I have a topology of client <-> hpsw3 <-> hpsw1 <-> server . I >>>>>> performed a wget operation from client to server. Following is the >>>>>> control traffic sent/received by the controller (Timestamp was what my >>>>>> tcpdump captured): >>>>>> >>>>>> 1266984715.446715 PACKET_IN hpsw3 >>>>>> 1266984715.446895 FLOW_MOD hpsw3 >>>>>> 1266984715.446936 PACKET_OUT hpsw3 >>>>>> >>>>>> 1266984715.452756 PACKET_IN hpsw1 >>>>>> 1266984715.452913 FLOW_MOD hpsw1 >>>>>> 1266984715.452937 PACKET_OUT hpsw1 >>>>>> >>>>>> Ideally, I would've expected to see the controller to push out the >>>>>> second FLOW_MOD soon enough (and not 6 ms after the PACKET_OUT). >>>>>> >>>>>> When I use NOX0.4, the action sequence is: >>>>>> 1266987591.116579 PACKET_IN hpsw3 >>>>>> 1266987591.116725 FLOW_MOD hpsw3 >>>>>> 1266987591.116755 FLOW_MOD hpsw1 >>>>>> 1266987591.116787 PACKET_OUT hpsw3 >>>>>> >>>>>> Any idea if there is a code change? >>>>>> >>>>>> Thanks >>>>>> Srini. >>>>>> >>>>>> _______________________________________________ >>>>>> nox-dev mailing list >>>>>> [email protected] >>>>>> http://noxrepo.org/mailman/listinfo/nox-dev_noxrepo.org >>>>>> >>>>>> >>>>>> >>>>> >>>>> _______________________________________________ >>>>> nox-dev mailing list >>>>> [email protected] >>>>> http://noxrepo.org/mailman/listinfo/nox-dev_noxrepo.org >>>>> >>>>> >>>>> >>> >>> > > _______________________________________________ nox-dev mailing list [email protected] http://noxrepo.org/mailman/listinfo/nox-dev_noxrepo.org
