Thank You. I threaded upon the TCP port details and re-ran on a simple linear topology. I can confirm it works OK. 3 switches , 3 different DPIDs and LLDP packets are indeed forwarded as expected.
I will get back checking my topology. Thanks Again! Cheers! Durga On Wed, May 21, 2014 at 10:41 AM, Murphy McCauley <murphy.mccau...@gmail.com > wrote: > > On May 20, 2014, at 3:55 PM, durga <c.vijaya.du...@gmail.com> wrote: > > May be I am misinterpreting Wireshark , but I see that the LLDP packet is > received on the sender switch , but on a different port. > > Example:Switch (DpID:3 ) is instructed to send a LLDP packet on port 2 . > That would be the first OFP_LLDP packet out message in the below screenshot. > the second row, is a packet in message, received on port 3 of the switch > (dpid 3) ,with the LLDP packet as payload . > I did look for other packets captured too, but I see that LLDP packet sent > out from one port of a switch is received and passed to the controller via > another port, but not by another switch. > > > How do you know they're the same switch? I suspect they are different > switches. The outermost ethernet addresses are all 00:00:00:00:00:00, so > they're not helpful for telling them apart. Look at the TCP port numbers. > The highlighted packet is using TCP port 44043 for the OpenFlow > connection. What port number is being used for the TCP connection in the > packet above it (which sent the packet-out)? I doubt it's 44043 -- > different port number, different OpenFlow control connection, different > switch. To more fully convince yourself, use Wireshark's "Conversation > filter" on one of those packets, and I doubt you see both of them in the > filtered list. Follow back until you find a features reply at the > beginning of the stream, and the DPID in it probably doesn't match the one > in the packet-in LLDP messages. > > Unless, of course, your topology has loops or you OpenFlow forwarding code > is instructing switches to forward the LLDP messages back or something. > > -- Murphy > > > > Am I missing something obvious or did not understand properly here? > > > Cheers! > Durga > > > > On Wed, May 21, 2014 at 7:14 AM, Murphy McCauley < > murphy.mccau...@gmail.com> wrote: > >> >> On May 20, 2014, at 1:51 AM, durga <c.vijaya.du...@gmail.com> wrote: >> >> Hello All, >> >> This question is w.r.t LLDP . Upon bootup - controller instructs switch >> to 'packet-out' LLDP protocol on its interface. Lets say SW1, P1. If the >> topology is SW1.P1<—> SW2.P2, I would expect SW2 to send an OF message to >> the controller with payload of the LLDP received from SW1.P1. That way the >> controller can establish that SW1.P1 is indeed connected to SW2.P1. >> >> >> Right. >> >> But when I run openflow/discovery.py , I notice that SW2.P1 is sending >> an LLDP packet with its own details iw SW2.P1 and not SW1.P1 , >> >> >> What makes you think that? It shouldn't be the case. >> >> may be my understanding is incorrect, but how exaclty is the controller >> able to conclude SW1.P1 is connected to SW2.P1? >> >> controller logs: >> >> INFO:openflow.of_01:[None 6] closed >> INFO:openflow.of_01:[00-00-00-00-00-01 7] connected >> DEBUG:discovery:Installing flow for 00-00-00-00-00-01 >> INFO:openflow.of_01:[00-00-00-00-00-02 8] connected >> DEBUG:discovery:Installing flow for 00-00-00-00-00-02 >> INFO:discovery:link detected: 00-00-00-00-00-01.2 -> 00-00-00-00-00-02.2 >> INFO:discovery:link detected: 00-00-00-00-00-02.2 -> 00-00-00-00-00-01.2 >> >> >> screenshot: >> >> >> >> Cheers! >> Durga >> >> >> > >
