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Mininet Open VSwitch 2.5

 
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Florian_Baaske
Occasional Contributor

Mininet Open VSwitch 2.5

Hi,

I'm testing the HPE VAN SDN Controller together with mininet. After upgrading the internal Open VSwitch from Mininet to the latest version, the controller creates a lot of (<100) goto table entries in the flow table, which ends up in no traffic is going through the swtich, as the switch drops the packets after 65 goto table actions. Any thing I can do to avoid this? 

Many thanks,
Florian

3 REPLIES 3
Solution

Re: Mininet Open VSwitch 2.5

Hi Florian,

When any switch connects to the controller, the controller will issue a multi-part request where it asks for the table_features of the switch. For each table that the switch reports, the controller will automatically insert a match=*,goto=NEXT flow at priority=0 to make sure that flows are seen by all tables. The last table is initialized with either output=CONTROLLER or output=NORMAL, depending upon the ControllerManager:hybrid.mode setting.

I believe that mininet reports 256 tables, therefore the controller would push one goto instruction to each of the first 255 tables, then an output=NORMAL instruction to the last table (with the default VAN settings). If mininet is not accepting a goto instruction in each table, then that may be an issue we'd need to raise for the mininet/OVS software (we should be able to program each table).

We have only verified compatibility with OVS 2.3.2, as noted in the VAN application support matrix:
   http://h20564.www2.hpe.com/hpsc/doc/public/display?docId=c05040231
You may want to downgrade to that version, unless you need the features of 2.5. If you need features in 2.5, we can try to figure out what's being rejected by mininet. If you take a .pcap on the control-plane when the switch connects to the VAN controller, that would be easiest to diagnose (or you can use "OpenFlow Monitor" in the VAN GUI).

Shaun

I am an HPE Employee
Florian_Baaske
Occasional Contributor

Re: Mininet Open VSwitch 2.5

Hi Shaun,

thanks for your answer. I think, the problem with the goto statement is, that every time a packet is send to the next table, an internal value is lowered for this packet and at table 65 reaches 0, which means the packet is droped. I downgraded to 2.3.2 yesterday and I did not see those goto statements anymore. Looks like there is something different in new versions of the open Vswitch. I will now check if the this version supports all the needed features, but so far, it looks quite well. 

Many thanks,
Florian

Florian_Baaske
Occasional Contributor

Re: Mininet Open VSwitch 2.5

Hi Shaun,

downgrading solved the issue. Thanks for helping, really appreciated.

Many thanks,
Florian