[Olsr-users] Received message to big to be forwarded

[Ferry Huberts]

Then why are these packets too large?
Do you piggy-back something over olsrd that uses large messages?

On 17/04/15 14:41, Henning Rogge wrote:
> Yes,
>
> they can and will be distributed over multiple messages... if they
> don't fit into the local MTU.
>
> Henning
>
> On Fri, Apr 17, 2015 at 2:39 PM, Jernej Kos <(spam-protected)> wrote:
>> Hello!
>>
>> So the reason for these big messages is probably the fact that there are
>> nodes that have a lot of neighbours? Can these be split over multiple
>> messages or not?
>>
>>
>> Jernej
>>
>> On 17. 04. 2015 14:37, Henning Rogge wrote:
>>> Hi,
>>>
>>> I think olsrd (1) already can split packets along the messages... the
>>> problem happens when a message is too large even for a UDP packet of
>>> its own.
>>>
>>> Henning
>>>
>>> On Fri, Apr 17, 2015 at 2:34 PM, Ferry Huberts <(spam-protected)> wrote:
>>>> OTOH
>>>>
>>>> We should be able to split packets with multiple messages into multiple
>>>> packets as long as the messages themselves aren't to big.
>>>> And also the reverse: merge packets for larger MTUs.
>>>>
>>>> IMHO olsrd should/can adapt to different MTU sizes.
>>>>
>>>> This most probably not go into v1 unless someone has a nice patch set (well
>>>> tested!). But I think it's a good idea for v2.
>>>>
>>>>
>>>> On 17/04/15 14:30, Henning Rogge wrote:
>>>>>
>>>>> The only other option I see is to set the MTU size for olsrd messages
>>>>> to 1280-40-8=1232 bytes... which should be guaranteed for all IPv6
>>>>> capable networks.
>>>>>
>>>>> Henning
>>>>>
>>>>> On Fri, Apr 17, 2015 at 2:25 PM, Ferry Huberts <(spam-protected)> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 17/04/15 14:22, Henning Rogge wrote:
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Apr 17, 2015 at 2:07 PM, Jernej Kos <(spam-protected)> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> Hello!
>>>>>>>>
>>>>>>>> We are seeing a lot of the following messages in our logs:
>>>>>>>>
>>>>>>>> Received message to big to be forwarded on digger1226(1296 bytes)!
>>>>>>>> Received message to big to be forwarded on digger1346(1328 bytes)!
>>>>>>>>
>>>>>>>> The message sizes indicate that the OLSR messages that are to be
>>>>>>>> forwarded are probably larger than the MTU (the OLSR daemon has
>>>>>>>> multiple
>>>>>>>> interfaces with different MTU sizes). Does this warning indicate some
>>>>>>>> problems with propagating routing information as messages are dropped
>>>>>>>> instead of being forwarded?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> The problem is that olsrd cannot fragment messages (which are flooded
>>>>>>> through the whole mesh) hop-by-hop... which means a network with
>>>>>>> different MTU-sizes AND large neighborhoods (which produce huge
>>>>>>> messages) is a problem.
>>>>>>>
>>>>>>
>>>>>> Yes, you should really setup a lower MTU on all your nodes
>>>>>>
>>>>>>> Henning Rogge
>>>>>>>
>>>>>>
>>>>>> --
>>>>>> Ferry Huberts
>>>>
>>>>
>>>> --
>>>> Ferry Huberts
>>

-- 
Ferry Huberts