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

Chetan Bali chetan.bali at aricent.com
Wed Nov 26 09:17:51 UTC 2014


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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