From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Heffner Subject: [PATCH] ip(7) IP_PMTUDISC_PROBE Date: Tue, 27 Mar 2007 15:52:17 -0400 Message-ID: <460975F1.60901@psc.edu> References: <11746948063923-git-send-email-jheffner@psc.edu> <11746948061847-git-send-email-jheffner@psc.edu> <11746948063971-git-send-email-jheffner@psc.edu> <4609640D.7010709@psc.edu> <20070327193115.GA28138@one.firstfloor.org> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------010008000300070002030803" Cc: Andi Kleen , netdev To: Michael Kerrisk Return-path: Received: from mailer2.psc.edu ([128.182.66.106]:53682 "EHLO mailer2.psc.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752662AbXC0TwZ (ORCPT ); Tue, 27 Mar 2007 15:52:25 -0400 In-Reply-To: <20070327193115.GA28138@one.firstfloor.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org This is a multi-part message in MIME format. --------------010008000300070002030803 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Document new IP_PMTUDISC_PROBE value for IP_MTU_DISCOVERY. (Going into 2.6.22). Thanks, -John --------------010008000300070002030803 Content-Type: text/plain; x-mac-type="0"; x-mac-creator="0"; name="ip_mtu_probe.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="ip_mtu_probe.patch" diff -rU3 man-pages-2.43-a/man7/ip.7 man-pages-2.43-b/man7/ip.7 --- man-pages-2.43-a/man7/ip.7 2006-09-26 09:54:29.000000000 -0400 +++ man-pages-2.43-b/man7/ip.7 2007-03-27 15:46:18.000000000 -0400 @@ -515,6 +515,7 @@ IP_PMTUDISC_WANT:Use per-route settings. IP_PMTUDISC_DONT:Never do Path MTU Discovery. IP_PMTUDISC_DO:Always do Path MTU Discovery. +IP_PMTUDISC_PROBE:Set DF but ignore Path MTU. .TE When PMTU discovery is enabled the kernel automatically keeps track of @@ -550,6 +551,15 @@ with the .B IP_MTU option. + +It is possible to implement RFC 4821 MTU probing with +.B SOCK_DGRAM +of +.B SOCK_RAW +sockets by setting a value of IP_PMTUDISC_PROBE. This is also particularly +useful for diagnostic tools such as +.BR tracepath (8) +that wish to deliberately send probe packets larger than the observed Path MTU. .TP .B IP_MTU Retrieve the current known path MTU of the current socket. --------------010008000300070002030803--