Kim and Robin, NetFlow and sFlow can give you some idea how your network topology looks like, but it is difficult to draw a complete picture of the network with NetFlow/sFlow because they are not designed to do such a thing.
Theoretically NetFlow and sFlow can tell on which interface a particular flow traverses in the network and hence allows us to deduce the network topology from there. In order to do so, however, NetFlow/sFlow collector would have to correlate one flow record exported by one device to another flow record exported by another device. This is extremely difficult to do when there's a massive amount of flows in the network (and it is often the case). In some case (but it is not the case for OVS though), flow is "sampled" (meaning that not all packet are collected to generate flow records) and it makes topology discovery by NetFlow/sFlow even more difficult. Regards, --- Motonori Shindo On 2012/06/05, at 2:41, Robin Wang wrote: > Hi Kim, > > I found an email that indicates OVS doesn't have built-in support. But it was > a year ago, not sure whether it's supported now. > http://openvswitch.org/pipermail/discuss/2011-July/005400.html > > For sFlow, to me, it is similar to NetFlow, and usually used to track dynamic > traffic in a network with the help of flow collector. There're lots of > different collectors. What you can get through sFlow depends on what features > the collector provides, not OVS. Not sure if there's a collector provides > topology things. Maybe someone who is familiar with collector could give us > some advice. Thanks. > > Best, > Robin > > 2012/6/5 Kim, Hyojoon <jo...@gatech.edu> > Hi all, > > > > What is the most common way to do layer-2 network topology discovery in OVS? > Some searching gives me a hint that people install lldpd, and query that > table once it’s populated. Is this the most common way? > > > > I figured out there is no SNMP support in OVS, but there is sFlow. Is sFlow > in OVS capable of doing topology discovery? It gives me a feeling that it is > more about traffic monitoring. > > > > Thanks, > > Joon > > > _______________________________________________ > discuss mailing list > discuss@openvswitch.org > http://openvswitch.org/mailman/listinfo/discuss > > > _______________________________________________ > discuss mailing list > discuss@openvswitch.org > http://openvswitch.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
