[ovs-discuss] Flow Expiration returning zeros for byte/packet counts

David Erickson derickso at stanford.edu
Sun Nov 15 03:59:18 UTC 2009

Jesse Gross wrote:
> David Erickson wrote:
>> Jesse Gross wrote:
>>> David Erickson wrote:
>>>> The crux is the netflow message is matching the flow expiration.  
>>>> There was nothing in the ovs-vswitchd.log file other than messages 
>>>> about connecting to NOX and exiting fail-open mode, which was well 
>>>> before this test was performed.
>>> Can you try turning off segmentation offload on the VM running 
>>> Apache?  Something like:
>>> ethtool -K eth0 tso off gso off
>> That fixed it.. is this something that needs to be done on every VM 
>> or something that can be fixed in OVS?
> I'm going to fix the stats of segmented packets in OVS so that TSO 
> doesn't need to be disabled.
> I also noticed that one of your other flows is off by the size of a 
> TCP SYN packet.  When you respond to a packet in do you send a packet 
> out plus a flow mod or is it a flow mod with a buffer ID?  If you send 
> a separate packet out then that packet is not counted as part of any 
> flow.
I saw this as well, I'm sure its a packet out with or without buffer, 
plus flowmod.  I'm fine with being a packet off, its just being an order 
of magnitude off and 10 meg off in traffic is a bit of a problem ;)
> Thanks for all your help in tracing down these issues.
Thank you for the fixes and great responses!


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