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

[Markus Kittenberger]

On Sun, Aug 12, 2012 at 2:06 PM, Michael Rack <
(spam-protected)> wrote:

>  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.
>
afair olsr does not split existing messages!

it will just not combine olsr-messages to packets that are too big for the
local interface mtu
(usually/often olsr-packets consist of multiple olsr-messages)

but if you have nodes that have enough neighbours to create > 1420 byte
long messages, you have a problem.

Markus


> 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 Freilassing            www.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)> 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
>> Nocksteinstr. 13                Fax.: +49 8654 670438
>> D-83395 Freilassing            www.rsm-freilassing.de
>>
>>
>> --
>> Olsr-users mailing list
>> (spam-protected)
>> https://lists.olsr.org/mailman/listinfo/olsr-users
>>
>
>
>
> --
> Olsr-users mailing list
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