Hi Murphy,
Thanks for your replying, and now I use wildcard the nw_tos field to avoid the flow match problem. But I want to ask why during the connection between OpenFlow switch and POX controller, POX command line usually dump some information like below: [packet ] (dhcp parse) warning DHCP packet data too short to parse header: data len 86 Is this invoke by the arp broadcast or the other problems? Thanks again. 2013/5/15 Murphy McCauley <[email protected]> > On May 15, 2013, at 2:14 AM, chenli wrote: > > > I did some test again, and it's so strange that the back flow for ssh > connection needs the field of nw_tos=16. > > I don't think this is strange. I believe 16 is the TOS value for minimize > delay, which makes sense for ssh, since it's interactive. The server is > likely setting it on purpose. > > > If the field for nw_tos equals to 0, the flow can't match correctly. > Just like below > > I'm not clear why this a problem. If its really troublesome for some > reason, you could always wildcard it... > > > And how can I find the flow_mods that correspond to these flows in POX? > > That depends on what application you're running in POX. If you're using > l2_learning, for example, it's wherever the flow_mod is in there. > l2_learning uses ofp_match.from_packet() to create a flow which exactly > matches the packet it's given. This includes the TOS field. You could > just insert a match.nw_tos = None to wildcard it... > > > -- Murphy
