[ovs-discuss] Limit on num of flows in ovs 2.0

[Ben Pfaff]

Since all of the packets are getting output, there's no actual problem.
The flows in the datapath flow table are an implementation detail.  It's
not a concern that fewer than 2000 flows are getting added to the
datapath.

On Wed, Nov 26, 2014 at 09:17:51AM +0000, Chetan Bali wrote:
> Hi Ben,
> 
> I am adding 2000 flows and sending traffic for all the 2000 flows. When 1 packet per flow is send ,I am getting all the 2000 packets at the output interface.
> 
> From the logs,I can see that  2000 flows are getting added at the ovs, but the problem is that ovs is sending add flow request to datapath [ openvswitch.ko ] for only 1251 packets at a time, and only 1250 flows are added at the datapath for burst traffic.
> 
> I have taken the output of dump-flow command for ovs and datapath.
> 
> Flows count at ovs-ofctl:
> ovs-ofctl dump-flows br0 | wc -l
> 2000
> 
> Flows count at datapath [ ovs-dpctl ]:
> ovs-dpctl dump-flows | wc -l
> 1251
> 
> It is showing that entries for only 1251 flows is added in datapath table.
> 
> 1st flow of ovs-ofctl:
> 
> cookie=0x0, duration=35.037s, table=0, n_packets=0, n_bytes=0, idle_age=35, ip,in_port=1,dl_src=aa:bb:cc:44:44:44,dl_dst=55:55:55:55:55:55,nw_src=10.0.0.1,nw_dst=11.0.0.1 actions=output:2
> 
> we increment dl_src, dl_dst, nw_src, nw_dst by 1 and try to add 2K flows like this.
> 
> Thanks
> Chetan Bali
> 
> -----Original Message-----
> From: Ben Pfaff [mailto:blp at nicira.com]
> Sent: 25 November 2014 21:12
> To: Chetan Bali
> Cc: discuss at openvswitch.org
> Subject: Re: [ovs-discuss] Limit on num of flows in ovs 2.0
> 
> On Tue, Nov 25, 2014 at 09:41:19AM +0000, Chetan Bali wrote:
> > I have a query related to max number of flows added using ovs-ofctl on
> > a single ovs bridge. We are trying to find the max limit of ovs flows.
> >
> > When we add the flows using ovs-ofctl, we are able to add 2000 flows
> > from the ovs clis. But when we send the traffic for 2K flows, only
> > ~1250 flows gets added but still we receive the packet outs for 2K
> > flows.
> >
> > Is there any hard limit on number of flows been added at dpif linux
> > class?
> 
> There is no hard limit to the OpenFlow flow table.  We routinely run with hundreds of thousands of flows.  I'm confused--you imply that many of the flows you add don't really get added, but that doesn't make any sense.  Can you explain further?
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