[ovs-discuss] ErrorMsg after requesting flow stats using OpenFlow 15

Ben Pfaff blp at ovn.org
Sun Nov 11 20:35:50 UTC 2018

On Sun, Nov 11, 2018 at 09:12:03PM +0100, Jozef Valko wrote:
> Hello all,
> I am developing an SDN application using Ryu and Mininet. My goal is to
> develop security module on the top of Ryu controller. Therefore, I need a
> regular statistics update from the forwarders which are OVS bridges. For
> this purpose I am using OFPFlowStatsRequest function provided by Ryu
> parser. Below is the function which I am using:
> [image: image.png]
> This function runs in separate thread and sends the request every 10
> seconds.
> When I use this function with OpenFlow14 everything is fine, the controller
> receives flow stats from the forwarder. But when I try to trigger this
> function using OpenFlow15, the following error shows in the controller
> window:
> [image: image.png]
> I tried to google this issue, searched in the specification and Ryubook but
> I did not find any solution. Because Ryu doesn't crash, I suppose that this
> is OVS-related issue.
> The only difference between requests in OF14 and OF15 is the value of the
> field 'type'. In case of OF14 it is 1 and in case of OF15 it is 17. Here is
> the request before sending (OF15):
> [image: image.png]
> What can be an issue? How to properly request flow statistics from the OVS
> forwarders using Ryu and OpenFlow15?
> Versions of the applications:
> Mininet - 2.3.0d4
> Ryu - ryu-manager 4.29
> OVS - ovs_version: "2.9.0"
> PortStatsRequest function is working nicely in both OF14 and OF15.

OVS doesn't fully support OpenFlow 1.5 and does not enable it by
default, so I suppose that you turned it on yourself.  That is fine--we
are pleased to hear about problems with protocol versions that are not
yet complete.  Also, I don't see any problems with OF1.5 flow stats and
it seems to work OK in my own simple test case with ovs-ofctl.

However, for testing incomplete protocol versions, one should use the
latest version of Open vSwitch.  Please try the latest release v2.10.1
or what one can find on master.

Alternatively, if you can provide a hex dump of the message that Ryu is
sending OVS (or otherwise some kind of exact representation), I can test
that for you.

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