I'm sorry, you're absolutely right. I read your messages out-of-order and didn't notice it. Let me try to give you a more complete answer.
The issue with what you're asking is that the ability to "trace" a packet isn't a primitive directly exposed to you by any individual component of the system, and composing the functionality available to you to effect this goal is non-trivial. To the best of my knowledge, your options lie on a spectrum with two endpoints. On the one hand, you could dump traffic from all points in the network, filter that traffic looking for the packet being traced, and then deduce the path the packet took based on where it appeared. On the other, you could analyze the control logic in your system, and derive the path that the packet would take given your knowledge of policy, and of the packet you intend to trace. In some trivial cases (simple topology, light traffic-load), the former solution is entirely sufficient. Conversely, for other types of triviality (deterministic, straightforward control logic), the latter approach is probably best. In a sufficiently complex situation, however, where the topology is complex, where there's a lot of traffic, and/or where the control-logic isn't entirely known or non-deterministic (e.g. multipath routing), the ideal solution is a hybrid of both approaches: you analyze the control logic to determine a set of switches/paths upon which the packet is likely to travel, dump traffic from only those points in the network, and then filter for your packet. HTH, s On 04/16/2013 01:03 AM, yashwanth kp wrote: > I am trying tcpdump now. But sorry if I was redundant in asking the same > question but I had asked the question before I got the reply on mininet. > > > On Tue, Apr 16, 2013 at 11:18 AM, Saul St. John <[email protected] > <mailto:[email protected]>> wrote: > > Well, you could tcpdump every interface in your network, and grep for > the packet.... > > Seriously, though, you asked this question already on mininet-discuss, > and received good suggestions. Have you put any effort into learning the > tools that Bob suggested? > > On 04/14/2013 11:11 PM, yashwanth kp wrote: > > Hi all, > > > > How can I trace the path of the packet that is present in my custom > > created topology using mininet. I am using pox to run remote > controller. > > I want to know what is the path taken by a packet when I ping > between 2 > > different hosts. > > > > -- > > Regards, > > > > Yashwanth K P > > Final Year , B.Tech > > NITK, Surathkal > > Contact: +91-9538403606 > > > > > -- > Regards, > > Yashwanth K P > Final Year , B.Tech > NITK, Surathkal > Contact: +91-9538403606
