On 07/15/2013 12:13 PM, Jagdish Motwani wrote:
> On 07/13/2013 09:17 PM, Ben Greear wrote:
>> On 07/13/2013 01:29 AM, jagdish.motw...@elitecore.com wrote:
>>> Yes John,
>>> When i do the ping request, i can see the 2 ip fragments. Its the
>>> ping reply that is dropped by my igb interface.
>>
>> Is the replay also 2 packets? If not, the peer machine may have
>> wrong MTU.
>>
>> Thanks,
>> Ben
>>
> You are right Ben. Peer machine has MTU=1500 greater than my MTU=1000.
>
> So the reply is a single packet (which is bigger than my MTU).
>
> My problem is : By setting an MTU of 1000, my igb device drops all
> received packet having length more than 1000
>
> However e1000e allows me to receive such packets.
>
> Regards,
> Jagdish Motwani
e1000, e1000e and ixgbe, all of them can receive packets bigger than
MTU. Only igb cannot.
This may not be of much importance if i am talking about a single
mis-configured host.
But in case of a router there are some use cases where this can be helpful:
Consider if i am deploying a router in a network where there are
some hosts with MTU 1000 and some with 1500
If i set my route's MTU as 1500, hosts with MTU 1000 cannot receive
(some)packets from the router.
If i set my route's MTU as 1000, router cannot receive
(some)packets from hosts with MTU 1500.
The ideal solution would be to configure all hosts to have the same
MTU.
But if my route can receive packets bigger than its MTU then i can
easily set router's MTU to 1000 and things will be working fine.
Regards,
Jagdish Motwani
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