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

[Michael Rack]

After change the mtu and reestablishing the VPN-Tunnel, all works fine.
So OLSR relied on this settings.
Thanks a lot!

>  ~ # ip addr show dev tap107
> 179: tap107: <BROADCAST,UP,LOWER_UP> mtu 1420 qdisc pfifo_fast state 
> UNKNOWN qlen 500
>     link/ether ca:5c:f1:0d:c7:a7 brd ff:ff:ff:ff:ff:ff
>     inet 91.205.xxx.xxx/32 brd 255.255.255.255 scope global tap107
>     inet6 fe80::c85c:f1ff:fe0d:c7a7/64 scope link
>        valid_lft forever preferred_lft forever


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

Am 12.08.2012 14:06, schrieb Michael Rack:
> All right! That figures :)
>
> So i try to adjust the vpn-interface mtu settings. I hope OLSR splits 
> messages, that gets bigger then the maximum mtu / mss.
>
> Currently i use OLSR v0.6.2.
>
>> DebugLevel      0
>> IpVersion       4
>> FIBMetric       "flat"
>> ClearScreen     yes
>>
>> RtTable 100
>> RtTableDefault 253
>>
>> AllowNoInt      yes
>> TosValue        16
>>
>> Willingness             3
>> LinkQualityLevel        2
>> LinkQualityAlgorithm    "etx_ff"
>>
>> UseHysteresis   no
>> Pollrate        0.05
>> NicChgsPollInt  3.0
>>
>> TcRedundancy    2
>> MprCoverage     1
>>
>> InterfaceDefaults
>> {
>>   ...
>> }
>
> Liebe Grüße aus Freilassing,
>
> Michael Rack
> RSM Freilassing
> -- 
> RSM Freilassing                 Tel.: +49 8654 607110
> Nocksteinstr. 13                Fax.: +49 8654 670438
> D-83395 Freilassingwww.rsm-freilassing.de  
> Am 12.08.2012 01:09, schrieb Song Gao:
>> Hey Michael,
>>
>> I am probably not the best person to answer this but from my 
>> understanding, OLSRd uses MTU of the interface to decide packet size. 
>> The interface created by VPN tunnel should be setting proper MTU.
>>
>> Could you post your OLSRd config file as well as the version of OLSRd 
>> you are using?
>>
>>
>> Kind regards,
>> -- 
>> Song Gao
>> https://profiles.google.com/song.gao.beta/about
>>
>>
>>
>> On Sat, Aug 11, 2012 at 3:49 PM, Michael Rack 
>> <(spam-protected) 
>> <mailto:(spam-protected)>> wrote:
>>
>>     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
>>     DSL-Interface:
>>
>>         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
>>     <tel:%2B49%208654%20607110>
>>     Nocksteinstr. 13                Fax.: +49 8654 670438
>>     <tel:%2B49%208654%20670438>
>>     D-83395 Freilassing www.rsm-freilassing.de
>>     <http://www.rsm-freilassing.de>
>>
>>
>>     -- 
>>     Olsr-users mailing list
>>     (spam-protected) <mailto:(spam-protected)>
>>     https://lists.olsr.org/mailman/listinfo/olsr-users
>>
>>
>

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