Gigabit and MTU > 1500

Hi !

Currently, I have a linux router with a gigabit trunk to a 10/100 swith. 
This trunk passes vlan tag to different vlan interface in the linux box.

We will be adding a 24 port gigabit swith soon. We then will have a gigabit 
segment. On that segment, we plan on unsing jumbo frames (9000 or the like). 
So, I'll have to crank up the eth undelaying card of the linux router to 
9000 to support such packets. New vlan interface will default then to a mtu 
of 9000 (I think so).

But we have some other vlan that needs to stay at 1500. If I specify in the 
ifconfig command the MTU, will this work as I expected ?

Also, is there a way to specify de MTU in the ifcfg-vlanxxx file in 
sysconfig/network-scripts ?

Thansk

Nicolas