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Date:      Mon, 24 Mar 2014 10:55:33 +0100
From:      Luigi Rizzo <rizzo@iet.unipi.it>
To:        soumya panigrahi <soumyapanigrahi@gmail.com>
Cc:        Giuseppe Lettieri <giuseppe.lettieri73@gmail.com>, Vincenzo Maffione <v.maffione@gmail.com>, "freebsd-net@freebsd.org" <net@freebsd.org>
Subject:   Re: Handling Jumbo Packets
Message-ID:  <CA%2BhQ2%2BhAzch_Uuxppxka_-2N9%2BUtYmBLsVJqMyRO15bjBVDWuQ@mail.gmail.com>
In-Reply-To: <CADDTU%2BDYxnEwu%2BtWxfofrykd21JLpc3ps8Y28WwF4tgwXqid5A@mail.gmail.com>
References:  <CADDTU%2BCxQdkzktGnvj4SqpG2N-ccN1vNThtQUoue1H00Dkaf5A@mail.gmail.com> <CA%2BhQ2%2Bjjihzy1P=s%2BAtSzZfTmL-yLRgCh36331azw2OUTafiaQ@mail.gmail.com> <CADDTU%2BDYxnEwu%2BtWxfofrykd21JLpc3ps8Y28WwF4tgwXqid5A@mail.gmail.com>

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On Mon, Mar 24, 2014 at 10:47 AM, soumya panigrahi <
soumyapanigrahi@gmail.com> wrote:

>
> On Mon, Mar 24, 2014 at 2:45 PM, Luigi Rizzo <rizzo@iet.unipi.it> wrote:
>
>>
>>
>>
>> On Mon, Mar 24, 2014 at 7:40 AM, soumya panigrahi <
>> soumyapanigrahi@gmail.com> wrote:
>>
>>> Hi,
>>>
>>> First of all I would like to thank you all for developing an awesome
>>> packet capturing framework.
>>> I have been using it recently and find it very very fast and efficient.
>>>
>>> However off late I am trying to capture Jumbo packets on the network for
>>> the following scenario's but that doesn't seem to be working.
>>>
>>
>> the sysctl tree dev.netmap (on FreeBSD)
>> or the filesystem
>> /sys/module/netmap_lin/parameters
>> (on Linux)
>> have a number of parameters that control buffer numbers and sizes.
>> In particular "buf_size" is used to allocate packet buffers and
>> you can bump it up from 2048 to something larger to accommodate
>> jumbo buffers.
>>
>> Depending on the NIC you may need to do something in the initialization
>> of the NIC itself to allow sending/receiving frames larger than 1518
>> bytes,
>> but I'd just try and see whether it works for you now.
>>
>> cheers
>> luigi
>>
>
> Thanks a lot for the quick response.
> I will also try to see if we can handle Jumbo frames by tweaking the
> buf_size parameter on Linux.
> In addition can you advice if NetMap can de-fragment Jumbo packets that
> were fragmented as IP packets by intermediate IP device because of MTU size
> limitation?
>

no, netmap does not do fragmentation or reassembly

cheers
luigi
--



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