<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:p="urn:schemas-microsoft-com:office:powerpoint" xmlns:a="urn:schemas-microsoft-com:office:access" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882" xmlns:rs="urn:schemas-microsoft-com:rowset" xmlns:z="#RowsetSchema" xmlns:b="urn:schemas-microsoft-com:office:publisher" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:c="urn:schemas-microsoft-com:office:component:spreadsheet" xmlns:odc="urn:schemas-microsoft-com:office:odc" xmlns:oa="urn:schemas-microsoft-com:office:activation" xmlns:html="http://www.w3.org/TR/REC-html40" xmlns:q="http://schemas.xmlsoap.org/soap/envelope/" xmlns:rtc="http://microsoft.com/officenet/conferencing" xmlns:D="DAV:" xmlns:Repl="http://schemas.microsoft.com/repl/" xmlns:mt="http://schemas.microsoft.com/sharepoint/soap/meetings/" xmlns:x2="http://schemas.microsoft.com/office/excel/2003/xml" xmlns:ppda="http://www.passport.com/NameSpace.xsd" xmlns:ois="http://schemas.microsoft.com/sharepoint/soap/ois/" xmlns:dir="http://schemas.microsoft.com/sharepoint/soap/directory/" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:dsp="http://schemas.microsoft.com/sharepoint/dsp" xmlns:udc="http://schemas.microsoft.com/data/udc" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:sub="http://schemas.microsoft.com/sharepoint/soap/2002/1/alerts/" xmlns:ec="http://www.w3.org/2001/04/xmlenc#" xmlns:sp="http://schemas.microsoft.com/sharepoint/" xmlns:sps="http://schemas.microsoft.com/sharepoint/soap/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:udcs="http://schemas.microsoft.com/data/udc/soap" xmlns:udcxf="http://schemas.microsoft.com/data/udc/xmlfile" xmlns:udcp2p="http://schemas.microsoft.com/data/udc/parttopart" xmlns:wf="http://schemas.microsoft.com/sharepoint/soap/workflow/" xmlns:dsss="http://schemas.microsoft.com/office/2006/digsig-setup" xmlns:dssi="http://schemas.microsoft.com/office/2006/digsig" xmlns:mdssi="http://schemas.openxmlformats.org/package/2006/digital-signature" xmlns:mver="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns:mrels="http://schemas.openxmlformats.org/package/2006/relationships" xmlns:spwp="http://microsoft.com/sharepoint/webpartpages" xmlns:ex12t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:ex12m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:pptsl="http://schemas.microsoft.com/sharepoint/soap/SlideLibrary/" xmlns:spsl="http://microsoft.com/webservices/SharePointPortalServer/PublishedLinksService" xmlns:Z="urn:schemas-microsoft-com:" xmlns:st="" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Do we think that bufferbloat is just a WAN problem? I work on live media applications for LANs and campus networks. I'm seeing what I think could be characterized as bufferbloat in LAN equipment. The timescales on 1 Gb Ethernet are orders of magnitude shorter and the performance problems caused are in many cases a bit different but root cause and potential solutions are, I'm hoping, very similar.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Keeping the frame byte size small while the frame time has shrunk maintains the overhead at the same level. Again, this has been a conscious decision not a stubborn relic. Ethernet improvements have increased bandwidth by orders of magnitude. Do we really need to increase it by a couple percentage points more by reducing overhead for large payloads?<o:p></o:p></span></p><p class=MsoNormal style='text-indent:.5in'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The cost of that improved marginal bandwidth efficiency is a 6x increase in latency. Many applications would not notice an increase from 12 us to 72 us for a Gigabit switch hop. But on a large network it adds up, some applications are absolutely that sensitive (transaction processing, cluster computing, SANs) and (I thought I'd be preaching to the choir here) there's no way to ever recover the lost performance.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Kevin Gross<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Dave Taht [mailto:dave.taht@gmail.com] <br><b>Sent:</b> Friday, May 13, 2011 8:54 AM<br><b>To:</b> rick.jones2@hp.com<br><b>Cc:</b> Kevin Gross; bloat@lists.bufferbloat.net<br><b>Subject:</b> Re: [Bloat] Burst Loss<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On Fri, May 13, 2011 at 8:35 AM, Rick Jones <<a href="mailto:rick.jones2@hp.com">rick.jones2@hp.com</a>> wrote:<o:p></o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'>On Thu, 2011-05-12 at 23:00 -0600, Kevin Gross wrote:<br>> One of the principal reasons jumbo frames have not been standardized<br>> is due to latency concerns. I assume this group can appreciate the<br>> IEEE holding ground on this.<o:p></o:p></p></div><p class=MsoNormal>Thusfar at least, bloaters are fighting to eliminate 10s of milliseconds<br>of queuing delay. I don't think this list is worrying about the tens of<br>microseconds difference between the transmission time of a 9000 byte<br>frame at 1 GbE vs a 1500 byte frame, or the single digit microseconds<br>difference at 10 GbE.<o:p></o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'><br>Heh. With the first iteration of the bismark project I'm trying to get to where I have less than 30ms latency under load and have far larger problems to worry about than jumbo frames. I'll be lucky to manage 1/10th that (300ms) at this point. <br><br>Not, incidentally that I mind the idea of jumbo frames. It seems silly to be saddled with default frame sizes that made sense in the 70s, and in an age where we will be seeing ever more packet encapsulation, reducing the header size as a ratio to data size strikes me as a very worthy goal.<o:p></o:p></p></div></div></div></body></html>