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Re: How can disable HP 2920 software rate limit of an OpenFlow instance?

 
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How can disable HP 2920 software rate limit of an OpenFlow instance?

Hi everyone,

 

I configured HP-2920-24G J9726A (WB.15.12) with an OpenFlow instance, following this topology:

 

Host 1 -------------------------HP2920---------------------------Host 2

                                                                     |

                                                                     |

                                                               Host 3

 

I connected successfully between 3 hosts to each others, and I could see the flows by using command: sh openflow instance oflab flows. 

 

However, when I sent the traffic from Host 1 to Host 3 with iperf, the bandwith report on iperf server (host 3) was so smaller than on iperf client (host 1): 1,18 Mbps  compares to 784 Mbps.  I think the reason is the Software rate-limit on the switch, it is 100 packets per second. I tried to increase this value to maximum (2000 pps), the bandwith report on iperf server also increased to 23.5 Mbps, but it's still so small than what I sent, as well as compares to the bandwith without enabling OpenFlow instance.

 

Can any one can please guide me to disable the Software rate-limit on HP 2920? (I read in "HP Switch Software OpenFlow

Administrator's Guide", it says that the default value is 100 pps, can't we send/recieve a high bandwith like 700-800Mpbs in an Openflow instance?)

 

Thank you so much.  

 

2 REPLIES 2
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Solution

Re: How can disable HP 2920 software rate limit of an OpenFlow instance?

Hi anhn_nguyen 

 

You cannot fully disable the limiter. The switch CPU is not strong enough to hand line rate traffic and switch management function, hence it will not be able to give you line rate and as you have illustrated you can release the reigns of the CPU a bit but this will cause an increased CPU and could lead to other issues for instance you not being apple to get as many packet_in and packet_outs as your application would need or that flow programming could be slower.

 

The recommendation in general is to avoid using software flows and only use a very limited number as a last resort.  THis enables you to use the ASIC for forwarding decisions and not the software on the CPU and this is how you would acheive line rate traffic. You might also want to look at other HP switch models depending on what you want to acheive in the flow should you not be able to acheive it on the current switch model.

 

It is documented in the OpenFlow administrator guide for the software version of your switch what the requirements are for hardware based flows.

 

You should be able to find the appropriate guide at the following URL ( Yeah it is a very long URL)

http://h20565.www2.hp.com/portal/site/hpsc/template.PAGE/public/psi/manualsResults/?sp4ts.oid=1827663&spf_p.tpst=psiContentResults&spf_p.prp_psiContentResults=wsrp-navigationalState%3Daction%253Dmanualslist%257Cviewall%253Dtrue%257Clang%253Den&javax.portlet.begCacheTok=com.vignette.cachetoken&javax.portlet.endCacheTok=com.vignette.cachetoken

 

Just look at the document name and for example

HP OpenFlow 1.3 Administrator Guide Wired Switches K/KA/KB/WB 15.16

THis document is for the 15.16 software brances and covers switches that runs K.15.16.xxxx and KA.15.16.xxxx and KB.15.16.xxxx and WB.15.16.xxxx

 

 

Kind Regards

Gerhard

HP SDN Team

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Occasional Contributor

Re: How can disable HP 2920 software rate limit of an OpenFlow instance?

Dear Gerhard Roets,

 

Thank you so much for your answer, I'll try to explore the manuals.

 

Best regards,

Anh.