[c-nsp] 3750 running jumbo frames ?

[Jeff Fitzwater]

Thanks for all the info.   Thats what I thought, but I have people  
checking on me.

Case closed.


Jeff
On Jun 11, 2009, at 1:13 PM, Peter Rathlev wrote:

> On Thu, 2009-06-11 at 09:44 -0400, Jeff Fitzwater wrote:
>> We have the need to run two 3750 switches with jumbo frames (9000),
>> for a high performance data transfer application.  Both switches will
>> be manages by connections to a NON-JUMBO frame environment.   (That
>> is, if this will work)
>>
>> If I enable jumbo frames (which is a global change) and leave the
>> management interface MTU at 1500 so the switch will use 1500 as  
>> packet
>> size for all management, is there any NEGATIVE ISSUES I should be
>> aware because of them being connected to the non-jumbo environment?
>
> This will not present problems. As David mentions only L2 switched
> frames can be jumbo. Management-traffic wouldn't exceed the routing  
> MTU,
> which is 1500 bytes by default. Changing the "system jumbo mtu"  
> doesn't
> change the L3 MTU.
>
> Any TCP based L3 connection would use the lowest of the two endpoint
> MSSs anyway, so hosts connecting from 1500 byte MTU segments would
> always end up using 1500 byte MTU connections. Even if you could  
> adjust
> routing MTU to 9000 bytes you probably wouldn't face any problems.
>
> IMHO there would never be any negative effects from enabling 9000  
> bytes
> MTU, unless of course you explicitely WANT to limit the MTU.
>
> Regards,
> Peter
>
>