can I ask mtu question

Ricky Beam jfbeam at
Fri Jan 30 21:33:43 UTC 2009

On Fri, 30 Jan 2009 12:57:25 -0500, adrian kok  
<adriankok2000 at> wrote:
> What is max mtu in jumbo frame?

That depends on the hardware.  I've seen gear running as low as ~8k.  I'd  
have to consult standard, but I think the max is 10k (10240).

Keep in mind the switch is not the only device on the network with jumbo  
frame limits.  The NICs in your servers will also have limits.

> Do I need to reboot the switch to take effect after
> setting up it?

Again, this depends on the system.  Many accept the change immediately,  
while others have to rebooted or interfaces reset to effect the change.

> if it doesn't need to reboot, How can I know the
> switch is running fine in this mtu 9000? eg: cisco
> any tools to check?

"ping" will do.  Set the packet size larger than the normal MTU (1500) and  
see if it crosses the network intact.  If it's not working, A) the packets  
will be dropped, and B) the "oversized frame" counter (among others)  
should be clocking errors.


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