[asterisk-users] Voice broken during calls (again...)

[Luca Bertoncello]

Am 23.06.2020 09:28, schrieb Marek Greško:

Hi

> if you need clampmss then it is highly probable there is a PMTU
> discovery problem. The clampmss does not work for UDP.

Is there a way to check if I have this problem?

> I probably counted the size incorrectly. So you are able to ping with
> size 1464 and not with 1466. How about trying same ping sizes from the
> internet towards your site? I mean trying to ping from sites with
> higher MTU than yours without lower MTU links in the path.

lucabert at ns:~$ ping -4 -M  do -s 1465 bpi.d.lucabert.com
PING bpi.d.lucabert.com (93.241.91.232) 1465(1493) bytes of data.
 From 62.156.246.57 (62.156.246.57) icmp_seq=1 Frag needed and DF set 
(mtu = 1492)
ping: local error: Message too long, mtu=1492
ping: local error: Message too long, mtu=1492
ping: local error: Message too long, mtu=1492
^C
--- bpi.d.lucabert.com ping statistics ---
4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 
3965ms
pipe 2

With paket size of 1464 it works...

> You know MTU is a size of l2 frame, so using ipv6 you are able to use
> higher payload sizes because of ip header size.

OK, thanks!
Luca Bertoncello
(lucabert at lucabert.de)