On 22/01/14 01:52, cmsv wrote:
> inline:
> 
> On 01/21/2014 07:31 PM, Antonio Quartulli wrote:
>> On 22/01/14 01:29, cmsv wrote:
>>>
>>>
>>> On 01/21/2014 07:20 PM, Antonio Quartulli wrote:
>>>> On 22/01/14 01:14, cmsv wrote:
>>>>>
>>>>>
>>>>> On 01/21/2014 07:06 PM, Antonio Quartulli wrote:
>>>>>> On 22/01/14 01:00, Antonio Quartulli wrote:
>>>>>>> On 21/01/14 21:01, cmsv wrote:
>>>>>>>> Yes i understand that but it keeps on increasing.
>>>>>>>> [   28.600000] batman_adv: bat0: The MTU of interface adhoc0 is too
>>>>>>>> small (1546) to handle the transport of batman-adv packets. Packets
>>>>>>>> going over this interface will be fragmented on layer2 which could
>>>>>>>> impact the performance. Setting the MTU to 1560 would solve the problem.
>>>>>>>
>>>>>>> Have you tried applying this patch before testing it once again?
>>>>>>>
>>>>>>> http://git.open-mesh.org/batman-adv.git/commit/746d6436f88899a79c1cb3b27af0614510368bb7
>>>>>>>
>>>>>>
>>>>>> Actually this patch is already part of the batman-adv package in openwrt.
>>>>>> Therefore the question turns in: did you update the batman-adv package
>>>>>> before performing your second test?
>>>>>
>>>>> the second test was done today and  yesterday's i updated bataman-adv.
>>>>
>>>> Yes but we are creating confusion.
>>> Maybe. Lets see.
>>>>
>>>> In the second test you *enabled* network coding, therefore it is normal
>>>> that the overhead grew up. This happens because NC uses more bytes for
>>>> its header.
>>>
>>>
>>> In both tests NC was enabled. I have NC enabled by default before and
>>> after the update.
>>> In fact is all tests NC is enabled by default and i undestand the
>>> increase to 1546 but to 1560 it surprised me.
>>> Should i still see the increase to 1560  or should it stayed at 1546
>>> which would be 1532 ?
>>>
>>>
>>
>> [Please don't remove the batman-adv mailing list from the CC field.]
>>
> unintentional mistake of too many buttons around :P
> 
>>
>> The first test you have performed was without the patch that fixes the
>> value reported in that message.
>>
>>
>>
>> Now that the patch is applied you have to see 1560 when NC is enabled
>> and 1532 when it is disabled.
> 
> Doing some tests and with NC disabled:
> 
>  uci show batman-adv | grep network_coding
> batman-adv.bat0.network_coding=0
> 
> after reboot:
> 
> # dmesg | grep MTU
> [   28.030000] batman_adv: bat0: The MTU of interface adhoc0 is too
> small (1546) to handle the transport of batman-adv packets. Packets
> going over this interface will be fragmented on layer2 which could
> impact the performance. Setting the MTU to 1560 would solve the problem.
> 
>  uci show network | grep mtu
> network.mesh0.mtu=1546
> 
> changing the mtu to 1560 when NC is disabled:
> 
> # uci show batman-adv | grep network_coding
> batman-adv.bat0.network_coding=0
> 
> # dmesg | grep MTU
> no output/result
> 
> # ifconfig | grep MTU
>           UP BROADCAST RUNNING MULTICAST  MTU:1560  Metric:1
>           UP BROADCAST RUNNING MULTICAST  MTU:1440  Metric:1
>           UP BROADCAST RUNNING MULTICAST  MTU:1440  Metric:1
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           UP LOOPBACK RUNNING  MTU:16436  Metric:1
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> 
> Frist result if the adhoc interface with 1560
> 
> correct me if i am mistaken but according to you it should be 1532 ?
> 
> Changing it to 1532 still keeping network coding disabled.
> 
> uci set network.mesh0.mtu=1532
> uci commit network
> reboot
> 
>  uci show network| grep mtu
> network.mesh0.mtu=1532
> 
>  uci show batman-adv | grep network_coding
> batman-adv.bat0.network_coding=0

No, the MTU value changes only when NC is disabled at compile time.


-- 
Antonio Quartulli