The question "why does my network with loops not work with a learning switch?" is a frequently asked question (FAQ), but the answer is readily apparent apparent once one states the question in this form.
However, it gives rise to two subtler questions which are FABNAQs - Frequently Asked But Never (or rarely adequately) Answered Questions: 1. What precisely is the command to start up NOX controlling an L2/bridged network running spanning tree or equivalent? One might think it would be ./nox_core -i ptcp: switch spanning_tree - but I don't think that's correct actually. 2. What modules in NOX (if any) may be combined to do reasonable multipath routing? What is the correct command line to invoke them? One might think it would be ./nox_core -i ptcp: normal_routing - but I don't think that's correct either. ;-) NOX is a controller framework where in general one is supposed to write one's own controller. However, most people find writing controllers to be work that they are uninterested in doing, and would greatly prefer to use use canned components. NOX provides several canned components, but it's not obvious how to use them. It seems likely that these questions are answered somewhere in the NOX documentation, but they should be featured more prominently in a NOX FAQ I think. -Bob On Jun 3, 2012, at 1:00 PM, Murphy McCauley wrote: > It may be as simple as adding spanning_tree to your commandline. > > -- Murphy > > On Jun 3, 2012 12:56 PM, "Brandon Heller" <[email protected]> wrote: > On Sun, Jun 3, 2012 at 5:26 AM, Anthony Salim <[email protected]> > wrote: > Hi all, > > I am creating a topology something like this diagram: > > h1 --- s1-----s2 ----h2 > | | > | | > s3----s4 > > my links in mininet is: > > s1.linkTo(s2) > s2.linkTo(s3) > s2.linkTo(s4) > s4.linkTo(s3) > > i have run the mininet and the nox controller but somehow when i tried to > ping all, the connection cant get through (its like in the infinite loop), > how can i resolve this? Thanks. > > Your topology has a loop. The default nox controller doesn't handle loops, > and melts down the network. This problem has nothing to do with Mininet, and > would happen with hardware switches too. > > You can resolve this by enabling spanning tree in NOX or implementing this > yourself. Perhaps this is noted in the NOX docs, or someone here can point > you in the right direction. > > -b > > > > Regards, > Anthony >
