[ovs-discuss] Flow Monitoring

Ben Pfaff blp at ovn.org
Thu May 23 21:54:05 UTC 2019


On Thu, May 23, 2019 at 04:37:41PM -0400, Vasu Dasari wrote:
> There are two "flags" fields in tcpdump output I shared earlier.
> 1. First one is 0 which is part of OFPT_MULTIPART_REQUEST, saying there are
> no more parts. This is first two bytes in row 0040
> 2. And second one is "00 01" and it is indicating to receive "add"
> notifications. And these are 2nd two bytes in row 0050.
> 
> Can you tell which bytes do you think are representing "flags" field in
> above bytes output?
> 
> You can open the pcap file in Wireshark to see my analysis.

Stripping off the TCP and other headers, we have the following:

00000000  05 12 00 28 00 00 00 00-00 10 00 00 00 00 00 00 |...(............|
00000010  05 f5 e1 00 00 00 00 00-ff ff ff ff 00 01 00 00 |................|
00000020  00 01 00 04 00 00 00 00-                        |........        |

"05 f5 e1 00" is the id, the following 00 00 is the flags.

> Also, is there a specification for nicera extensions? Can you please point
> it to me?

Beyond the 100+ relevant lines of comments in nicira-ext.h?  No.


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