[ovs-discuss] Wireshark Dissector for Nicira Extensions

Vasu Dasari vdasari at gmail.com
Sat Feb 1 19:20:51 UTC 2014


Sure. I can look at this. Can you share a  sample pcap file with the
scenario you outlined. I can make changes to the code to work in your
and my pcap scenario.

Vasu

Sent from my iPhone

> On Feb 1, 2014, at 11:42 AM, Ben Pfaff <blp at nicira.com> wrote:
>
> I see.  Handling this case would require some extra code.  It also
> raises the question of how to detect the start of an OpenFlow message
> within a TCP stream, since any given TCP segment might begin in the
> middle of an OpenFlow message.  One could ignore the problem, but then
> there might be a lot of desynchronized garbage in the output stream.
>
> If you want to contribute a patch that works toward better handling
> here, that would be nice.
>
>> On Sat, Feb 01, 2014 at 10:45:39AM -0500, Vasu Dasari wrote:
>> No I do not have them. The pcap is an extract of OF packets alone. I am
>> attaching the pcap I used here.
>>
>> -Vasu
>>
>>
>>> On Sat, Feb 1, 2014 at 10:34 AM, Ben Pfaff <blp at nicira.com> wrote:
>>>
>>>> On Sat, Feb 01, 2014 at 08:46:27AM -0500, Vasu Dasari wrote:
>>>> Thanks Ben. I was using 2.09. When I updated my git, I could see the
>>>> command you suggested. But, unfortunately it was not working.
>>>>
>>>> vdasari at mininet:~$ ovs-ofctl ofp-parse-pcap of.pcap
>>>> vdasari at mininet:~$
>>>>
>>>> On digging through the code, I found that there could be an issue with
>>>> tcp_reader_run() or tcp_stream_lookup() and seq_no. "stream->seq_no is
>>>> always 0". Once I force the code to return the "payload" by not checking
>>>> for seq_no,, from tcp_reader_run() function, I could see the right
>>>> output.And this logic is working for me. Probably there is something you
>>>> had thought of regarding sequence numbers which I might be overlooking.
>>>
>>> Does your pcap file include the start of the TCP connection (the SYN and
>>> SYN/ACK packets)?  I am not sure that I tested without that.
>
>



More information about the discuss mailing list