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HP3500yl- flows slow each other down when ports are disjoint

Occasional Advisor

HP3500yl- flows slow each other down when ports are disjoint



The problem we are getting is when we have 4 machines connected to port number 1,2,3,4 of hp 3500yl switch,
we found traffic from port 1 to port 2, and port 3 to port 4 will conflict with each other. When these traffic are sent simultaneously, they only get half of the bandwidth(around 30Mbit/s) compared with the full bandwidth when are sent individually(64Mbits/s). Since the ports are disjoint, we think there is a problem there. It seems the flows are sharing a big queue inside the switch. The output of show-tech-all is attached. I would like to know if it is normal for 3500yl switch, or there is some configuration problem there? Thank you!

Occasional Advisor

Re: HP3500yl- flows slow each other down when ports are disjoint

I also want to add that the problem might be due to all the flows for the openflow
instance are processed in software.
Output for show openflow isntance vlan2:

HP-Switch2# show openflow instance vlan2      


 Configured OF Version    : 1.3       

 Negotiated OF Version    : 1.0  

 Instance Name            : vlan2                            

 Admin. Status            : Enabled 

 Member List              : VLAN 2              

 Listen Port              : 6633           

 Oper. Status             : Up      

 Oper. Status Reason      : NA                                      

 Datapath ID              : 00022c27d7787280        

 Mode                     : Active    

 Flow Location            : Hardware and Software         

 No. of Hw Flows          : 0     

 No. of Sw Flows          : 26    

 Hw. Rate Limit           : 10000000 kbps       

 Sw. Rate Limit           : 10000 pps      

 Conn. Interrupt Mode     : Fail-Secure         

 Maximum Backoff Interval : 1 seconds      

 Probe Interval           : 10 seconds     

 Hw. Table Miss Count     : NA                  

 No. of Sw Flow Tables    : 1  

 Egress Only Ports        : None                                    

 Table Model              : Single Table                            


 Controller Id Connection Status Connection State Secure Role  

 ------------- ----------------- ---------------- ------ ------

 1             Connected         Active           No     Equal 

 2             Disconnected      Backoff          No     Equal 



               You can see we have 26 software flows and 0 hardware flows. The limit for software flows is 10000 packet/s, which means the entire openflow instance vlan2(port 1 to port 12), can only send 10000 packets/s. This is the maximum limit one can set for openflow instance. So we might need to find a way to process flows in hardware.

Esteemed Contributor

Re: HP3500yl- flows slow each other down when ports are disjoint

Hi chrisxcai 


You are right the fact is software flows will not give you close to line rate.


There is a finite number of software resources. I have also noticed you are using OpenFlow 1.0(Negotiated) it might be a good idea to try to get to OF 1.3. The flow tables on the switch will help you identify hardware and software flows easier and well the capibilities of each is list in the software version your using's OpenFLow Administration guide.


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


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