[Olsr-users] Too big packets | > 1420 Bytes!

Michael Rack (spam-protected)
Sat Aug 11 22:49:05 CEST 2012

Hi OLSR-Users!

I have a VPN-Tunnel that runs over a PPPoE-Link, so i have only 1492 
Bytes available. The VPN-Tunnel is established via UDP, so i have 8 
Bytes (MAC), and 12 Bytes (UDP) overhead. So the remaining MTU is 1472 
Bytes for the inner Layer-2.

So there are 1452 Bytes left for OLSR.

But OLSR currently send out packets with more then 1452 Bytes, so the 
VPN-Tunnel goes down and automatically get reestablished.

> Aug 11 21:18:50 vtund[6598]: Session 
> neubichl-dsl-backup[79.192.xxx.xxx:46105] opened
> Aug 11 21:18:50 vtund[6598]: UDP connection initialized
> Aug 11 21:19:29 vtund[6598]: Message too long (90)
> Aug 11 21:19:29 vtund[6598]: Session neubichl-dsl-backup closed

currently i drop packages over 1420 bytes that are passing the 
> iptables -A OUTPUT -o tap107 -m length --length 1420: -j DROP

since that, the VPN-Tunnel is stable.

> ~ # ip route show table olsr-network | wc -l
> 84

currently there are 84 routes spreaded over the whole network via OLSR. 
That can not result in a so high package size? How can i reduce the 
packet-size, or what have to be done, so olsr does not eat up more then 
1400 Bytes?

Liebe Grüße aus Freilassing,

Michael Rack
RSM Freilassing
RSM Freilassing                 Tel.: +49 8654 607110
Nocksteinstr. 13                Fax.: +49 8654 670438
D-83395 Freilassing            www.rsm-freilassing.de

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