topic Re: HP3500yl- flows slow each other down when ports are disjoint in Software Defined Networking

HP3500yl- flows slow each other down when ports are disjoint

chrisxcai — Wed, 12 Nov 2014 00:13:35 GMT

Hi,

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!

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

chrisxcai — Wed, 12 Nov 2014 02:11:14 GMT

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.

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

Gerhard Roets — Fri, 14 Nov 2014 10:04:52 GMT

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)

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