<div dir="ltr"><div><div>Thank you all for pointing me in the right direction.<br><br></div>Now I learned I have to care about MTU.<br><br></div>Best regards<br><div><div><div><div class="gmail_extra"><br><div class="gmail_quote">2016-03-03 21:27 GMT+01:00 Toufic Khreish (Gmail) <span dir="ltr"><<a href="mailto:toufic.khreish@gmail.com" target="_blank">toufic.khreish@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="white" link="#0563C1" vlink="#954F72" lang="EN-US"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Hello,<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">You need to determine the correct MTU value by doing the following:<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><p style="margin:0in;margin-bottom:.0001pt;line-height:15.0pt;background:white"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">ping <a href="http://www.google.com" target="_blank">www.google.com</a> -f -l 1400 and you go up or down<u></u><u></u></span></p><p style="margin:0in;margin-bottom:.0001pt;line-height:15.0pt;background:white;outline:none;text-align:start;word-spacing:0px"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> <u></u><u></u></span></p><p style="margin:0in;margin-bottom:.0001pt;line-height:15.0pt;background:white;outline:none;text-align:start;word-spacing:0px"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">An example: <br>1440 Max packet size from Ping Test<br>+ 28 IP and ICMP headers<br>1468 is your optimum MTU Setting<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Reference : </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;background:white"><a href="http://www.tp-link.fr/FAQ-190.html" target="_blank">http://www.tp-link.fr/FAQ-190.html</a><u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;background:white"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Once you determine the correct MTU you just set it on the VPN server, it will not break any connection the worst will be slow connection that is all.<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">From my experience the MTU value for 3G was 1400.<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Best regards<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Toufic<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p><div><div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext"> <a href="mailto:asterisk-users-bounces@lists.digium.com" target="_blank">asterisk-users-bounces@lists.digium.com</a> [mailto:<a href="mailto:asterisk-users-bounces@lists.digium.com" target="_blank">asterisk-users-bounces@lists.digium.com</a>] <b>On Behalf Of </b>Duncan<br><b>Sent:</b> Thursday, March 03, 2016 9:02 PM<br><b>To:</b> Asterisk Users Mailing List - Non-Commercial Discussion <<a href="mailto:asterisk-users@lists.digium.com" target="_blank">asterisk-users@lists.digium.com</a>><br><b>Subject:</b> Re: [asterisk-users] Rasterisk freeze on 4G link<u></u><u></u></span></p></div></div><div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">> With this new link, whenever I launch a vim, a nano or a rasterisk session, my terminal freezes (rasterisk) or remains empty (nano, vim).<br><br><u></u><u></u></p><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><div><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">><br>> When a session is frozon, I can open a new one at the same so it excludes a basic connectivity loss.<br>><br>Usually incorrect MTU gives you this effect. Use ping with MTU size set to test and find what works.<u></u><u></u></p></blockquote><div><p class="MsoNormal">I think its value: it's 1272, which amazes me. <u></u><u></u></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"><br>You will probably also break it with any large text dump eg cat /var/log/syslog will also do it<u></u><u></u></p></blockquote><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt">Yes "cat /var/log/syslog" also broke my console.<u></u><u></u></p></div><div><p class="MsoNormal">Why would my console break because of inadequate MTU and other PC on the same location, seem unaffected ?<u></u><u></u></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt">Because, they most probably mostly use SMTP and HTTP ?<u></u><u></u></p></div><div><p class="MsoNormal">Is possible to simulate a given MTU on a LAN to reproduce such freezes ?<u></u><u></u></p></div><div><p class="MsoNormal">(the remote location is at the other side of the country and I would like to prepare things as much as possible).<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></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"><u></u> <u></u></p></blockquote></div></div></div></blockquote><p class="MsoNormal">I think you need to go through a router or some device that can constrain the MTU. But live changing your server MTU should be straight forward as openvpn should try and reconnect, and you can change the server back. I haven't lost connectivity before with this<br><br>Also the session is probably timed out rather than gone, in 10-15 mins maybe less it will come back (or does for me) <br><br>Cheers Duncan<u></u><u></u></p></div></div></div></div><br>--<br>
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