[ovs-discuss] Flow Expiration returning zeros for byte/packet counts
derickso at stanford.edu
Fri Nov 13 00:34:31 UTC 2009
Jesse Gross wrote:
> David Erickson wrote:
>> This patch seemed to work but exposed another bizarre problem. So my
>> setup is the same, 2 Xen servers with OVS, 1 reference OF software
>> switch inbetween the two, a wget from .12 to .13 which is running
>> apache. When the flows expire, dpid 17 which is the OVS on the
>> physical machine running apache returns a flow expiration that is
>> ~10MB less than the other two flows, but the packet count is 164k
>> less.. I've attached the logs, it is reproducible on my end.
> I've been trying to reproduce this but so far haven't been able to. It
> would be great if you can give me some more information so that I can
> narrow down my search:
Hi Jesse, see inline:
> 1. If you query the flow stats before the expiration message, do you get
> the right results? You mentioned that this was true before but these
> flows are less than your 10 second polling interval.
The values still look wrong from the stats message, I just did a test
where I bumped up the polling rate so I would send a stats message while
the flow was idle but before timeout and got the following:
Nov 12 16:14:01 epic nox: 00087|Flow_tracker:DBG Posting an update
event- dpid: 003048b06117 duration: 16 pkt count: 58467 byte count 254630713
Nov 12 16:14:02 epic nox: 00101|Flow_tracker:DBG Flow expiration from
dpid: 003048b06117 duration: 16 pkts: 58467 bytes: 254630713 flow:
port0002:vlanffff mac22:db:ed:04:cb:a4->7a:4a:0f:e9:1b:bd proto0800
> 2. Does the problem also occur if you use wildcarded rules instead of
> exact match?
It actually gets worse, I wildcarded vlan and the expiration messages
now have 0's, but the stats message is similar to the above listed message.
> 3. When do you insert the flows? Before any packets are sent? In
> response to a packet in?
In response to a packet in.
> 4. Are the actions for the rules specific ports or OFPP_NORMAL?
> 5. Do you see similar results with NetFlow? You can use Wireshark as a
> simple NetFlow collector if you don't have one - just tell it to decode
> the traffic as cflow.
Can you give me more information on how to do this? IE are netflow
packets automatically broadcast out? IE if I start up tcpdump on xen's
dom0 which interface should I listen to? Do I need to explicitly tell
OVS somehow to pump out netflow messages?
> Any information that you can get will help.
Absolutely, if you need me to run a debug build or whatever I'm happy to
do it as long as it comes as an RPM :)
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