[asterisk-users] Rasterisk freeze on 4G link

Thu Mar 3 14:27:32 CST 2016

Hello,

You need to determine the correct MTU value by doing the following:

ping www.google.com -f -l 1400 and you go up or down

An example: 
1440 Max packet size from Ping Test
+ 28 IP and ICMP headers
1468 is your optimum MTU Setting

Reference : http://www.tp-link.fr/FAQ-190.html

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.

>From my experience the MTU value for 3G was 1400.

Best regards

Toufic

From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Duncan
Sent: Thursday, March 03, 2016 9:02 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
<asterisk-users at lists.digium.com>
Subject: Re: [asterisk-users] Rasterisk freeze on 4G link

> With this new link, whenever I launch a vim, a nano or a rasterisk
session, my terminal freezes (rasterisk) or remains empty (nano, vim).

>
> When a session is frozon, I can open a new one at the same so it excludes
a basic connectivity loss.
>
Usually incorrect MTU gives you this effect. Use ping with MTU size set to
test and find what works.

I think its value: it's 1272, which amazes me. 

You will probably also break it with any large text dump eg cat
/var/log/syslog will also do it

Yes  "cat /var/log/syslog" also broke my console.

Why would my console break because of inadequate MTU and other PC on the
same location, seem unaffected ?

Because, they most probably mostly use SMTP and HTTP ?

Is possible to simulate a given MTU on a LAN to reproduce such freezes ?

(the remote location is at the other side of the country and I would like to
prepare things as much as possible).

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

Also the session is probably timed out rather than gone, in 10-15 mins maybe
less it will come back (or does for me) 

Cheers Duncan

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.digium.com/pipermail/asterisk-users/attachments/20160303/6969b39b/attachment.html>