Hi, I always use the openflow.discovery as my topology module, however I met some strange behaviors recently and raise some questions.
The strange behaviors are that link time_out appear unexpectedly, which causes flow entry deleted ( I'm using l2_multi). But actually the link is good. The unexpected link time_out may happen in following cases, and more frequent if several cases at the same time: (1) If I keep requesting info from switches ( e.g. portstatus request). I'm wondering why the request causes this. Is that because the request flushes the LLDP packets? (2) If a new traffic is introduced. Is that because of the traffic to controller blocks LLDP during learning before flow installed? (3) If do flow entry modification. I guess the modification takes some time and during this time, many data packets are forwarded to controller and occupy control channel. Unfortuanately, My program is doing all the above for some intelligent routing. However the unexpected link time_out will fresh everything... It is still need to have the time_out because sometimes it is really a link disconnection. I'm requesting port_status every 2 seconds, and use the feed back to intelligent route. Is that because of LLDPs are blaocked by other packets in control channel and links cannot be updated? Is it possible to set highest priority for LLDP in control channel rather than others? If the data channel is almost fully occupied, will the LLDPs be blocked in that channel and be treated as link time_out? And another question is that: Why not only using port_status as link_event rather than link update? The most concern I can think probably is that some cables are really bad, but they are stilltreated connected for switches? Thanks very much. Weiyang
