<div dir="ltr"><p dir="ltr" style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap">Hi</span></p><p dir="ltr" style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap"> We are working on a research project that involves HP OpenFlow-enabled switch (HP 3500 yl). We are facing some issues with performance particularly when operating the switch in "OpenFlow" mode. The switch is controlled via a desktop running the Ryu controller.</span></p><p dir="ltr" style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap">The rules on the switch match packets based on the fields supported by OpenFlow. </span><span style="background-color:transparent;color:rgb(0,0,0);font-family:Arial;white-space:pre-wrap">Further, the switch also modifies a certain IP header field (in this case the ToS bits) for packets that match the rules and are hence forwarded. </span></p><br style="font-size:12.8px"><p dir="ltr" style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap">More precisely, the rules match the ToS bits of the packet and change them to a different value before forwarding them to a chosen host. </span></p><br style="font-size:12.8px"><p dir="ltr" style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap">However, in the process, the forwarded packets achieve a throughput of no more than 700kbps, while the source and destination hosts have 100 Mbit/s Ethernet ports.
If we disable "OpenFlow" mode and use it as it is then we achieve a full throughput of 100Mbit/s (the Ethernet link speeds of the client and server hosts). The end-to-end throughput was measured using <i>iperf</i>. </span></p><br style="font-size:12.8px"><p dir="ltr" style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap">Could someone shed some light on the reason for this drastic performance degradation? (all the switch does is match packets whose ToS value is (say,) 0x28 and replaces it with 0x40 before forwarding them to the right destination)</span></p><p style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap">Also, is there an alternative switch that someone has used successfully for similar things?</span></p><p dir="ltr" style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap"><br></span></p><p style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><font color="#000000" face="Arial"><span style="white-space:pre-wrap">A figure showing our experiment scenario is given below, for reference.</span></font></p><p style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><font color="#000000" face="Arial"><span style="white-space:pre-wrap"><br></span></font></p><p style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span id="gmail-m_5145701276715026701gmail-docs-internal-guid-c11bb866-3a82-3fbf-0933-de84c2432a8f"><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap"><img src="https://lh4.googleusercontent.com/LumzG5i05mYlMRS7MYOXJVAH8YH8KJUU4SJsfn--jjnTcY-kIWtCzzwR6Upcv8Acy-ljmHhYUW9UxHdEma3Wmg1WHOOc1GVWpa2hih-jt9LpyllqOTvy3FUbQGv7VghgiSG80FoI" width="401" height="328" class="gmail-CToWUd gmail-a6T" tabindex="0" style="border: none;"></span></span></p><p style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap"><br></span></span></p><p style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><font color="#000000" face="Arial"><span style="white-space:pre-wrap">Thanks,</span></font></p><p style="font-size:12.8px;line-height:1.38;margin-top:0pt;margin-bottom:0pt"><font color="#000000" face="Arial"><span style="white-space:pre-wrap">Chaitanya</span></font></p><div><br></div>
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