<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:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
p.msonormal0, li.msonormal0, div.msonormal0
{mso-style-name:msonormal;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;
mso-fareast-language:EN-US;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span style='mso-fareast-language:EN-US'>But MPLS can be made flow driven (it can be made whatever the policy dictates), for instance DSCP driven…<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>adam<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span lang=EN-US>From:</span></b><span lang=EN-US> NANOG <nanog-bounces+adamv0025=netconsultings.com@nanog.org> <b>On Behalf Of </b>Robert Raszuk<br><b>Sent:</b> Saturday, June 20, 2020 4:13 PM<br><b>To:</b> Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp><br><b>Cc:</b> North American Network Operators' Group <nanog@nanog.org><br><b>Subject:</b> Re: why am i in this handbasket? (was Devil's Advocate - Segment Routing, Why?)<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><p class=MsoNormal>The problem of MPLS, however, is that, it must also be flow driven,<br>because detailed route information at the destination is necessary<br>to prepare nested labels at the source, which costs a lot and should<br>be attempted only for detected flows.<o:p></o:p></p></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>MPLS is not flow driven. I sent some mail about it but perhaps it bounced. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>MPLS LDP or L3VPNs was NEVER flow driven. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Since day one till today it was and still is purely destination based. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Transport is using LSP to egress PE (dst IP). <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>L3VPNs are using either per dst prefix, or per CE or per VRF labels. No implementation does anything upon "flow detection" - to prepare any nested labels. Even in FIBs all information is preprogrammed in hierarchical fashion well before any flow packet arrives. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thx,<br>R.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><p class=MsoNormal style='margin-bottom:12.0pt'><br> > there is the argument that switching MPLS is faster than IP; when the<br> > pressure points i see are more at routing (BGP/LDP/RSVP/whatever),<br> > recovery, and convergence.<br><br>Routing table at IPv4 backbone today needs at most 16M entries to be<br>looked up by simple SRAM, which is as fast as MPLS look up, which is<br>one of a reason why we should obsolete IPv6.<br><br>Though resource reserved flows need their own routing table entries,<br>they should be charged proportional to duration of the reservation,<br>which can scale to afford the cost to have the entries.<br><br> Masataka Ohta<o:p></o:p></p></blockquote></div></div></div></div></body></html>