https://doc.cliss21.com/index.php?action=history&feed=atom&title=MTU 2026-06-03T23:40:32Z Historique des révisions pour cette page sur le wiki MediaWiki 1.35.4 https://doc.cliss21.com/index.php?title=MTU&diff=2899&oldid=prev 2007-11-08T13:46:13Z

<p></p> <table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="fr"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Version précédente</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Version du 8 novembre 2007 à 13:46</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1" >Ligne 1 :</td> <td colspan="2" class="diff-lineno">Ligne 1 :</td></tr> <tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Les problèmes de MTU, c'est une sombre histoire de taille de paquets IP plus ou moins bien découpés/recollés. Ça nous a bien ennuyés pour configurer un accès VPN - sans réelle solution au final. Quelques notes pour plus tard:</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Les problèmes de MTU, c'est une sombre histoire de taille de paquets IP plus ou moins bien découpés/recollés. Ça nous a bien ennuyés pour configurer un accès VPN - sans réelle solution au final. Quelques notes pour plus tard:</div></td></tr> <tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr> <tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>* on d'un ICMP unreachable, R1 initialise le MTU à 1000-24=976 octets</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>* on d'un ICMP unreachable, R1 initialise le MTU à 1000-24=976 octets <ins class="diffchange diffchange-inline">[</ins>http://www.cisco.com/web/CA/events/pdfs/1.6_Reseaux_prive_virtuels_VPN.pdf<ins class="diffchange diffchange-inline">]</ins></div></td></tr> <tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del class="diffchange diffchange-inline">  </del>http://www.cisco.com/web/CA/events/pdfs/1.6_Reseaux_prive_virtuels_VPN.pdf</div></td><td colspan="2"> </td></tr> <tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr> <tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* http://www.elifulkerson.com/projects/mturoute.php</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* http://www.elifulkerson.com/projects/mturoute.php</div></td></tr> </table>

imported>SylvainBeucler https://doc.cliss21.com/index.php?title=MTU&diff=2898&oldid=prev 2007-11-08T13:45:33Z

<p>Notes éparses sur le MTU</p> <p><b>Nouvelle page</b></p><div>Les problèmes de MTU, c'est une sombre histoire de taille de paquets IP plus ou moins bien découpés/recollés. Ça nous a bien ennuyés pour configurer un accès VPN - sans réelle solution au final. Quelques notes pour plus tard:<br /> <br /> * on d'un ICMP unreachable, R1 initialise le MTU à 1000-24=976 octets<br /> http://www.cisco.com/web/CA/events/pdfs/1.6_Reseaux_prive_virtuels_VPN.pdf<br /> <br /> * http://www.elifulkerson.com/projects/mturoute.php<br /> mturoute.exe -m 1425 10.10.0.1 -&gt; déconnexion<br /> # ICMP payload of 1423 bytes suceeded.<br /> # ICMP payload of 1424 bytes failed..<br /> <br /> mturoute.exe -m 1424 10.10.0.1 # -&gt; OK (behind Wanadoo)<br /> <br /> * man iptables: TCPMSS / (usually limiting it to your outgoing interface's MTU minus 40) =&gt; where does &quot;40&quot; comes from?<br /> <br /> * my pptpd-options<br /> #MTU stuff<br /> # 1500 is common for PPP<br /> # GRE adds a 24-bit header<br /> # =&gt; 1476<br /> # According to my tests (W98+NAT), not higher than 1455.<br /> mtu 1455<br /> mru 1455<br /> #default-mru<br /> <br /> # And according to mturoute.exe, my max is 1424 (connection hangs<br /> # whenever I try -m &gt; 1424). Note that the connexion never hangs if I<br /> # set mtu/mru to 1455 (but still fails with ICMP payload of 1424 or<br /> # more).<br /> <br /> # 1455 = 1500 - 24 - 20 (ip?) - 1?<br /> # whatever...<br /> <br /> # With a W2K behind Free, mturoute reports a max ICMP payload of 1372,<br /> # and a Path MTU of 1400 bytes. No disconnection to report whatever<br /> # the ppp MTU.<br /> <br /> # With a W98+QEMU+Free, mturoute reports a max ICMP payload of 1434,<br /> # and a Path MTU of 1462. No disconnection to report whatever<br /> # the ppp MTU.</div>

imported>SylvainBeucler