Setting MTU for 4500 series 1

[PHerrin]

I'm optimizing an iSCSI SAN deployment in my network and need some assistance setting up jumbo frames on the network switches, Cisco 4506's. I have created a separate vlan (55) to carry the iSCSI traffic and want to set that vlan to a max MTU of 9000, since there is active data on the vlan I want to make sure I update the system as not to disrupt the current hosts. I have limited switch configuration knowledge so please bear with me,
I can set the mtu on the vlan using the
#Config t
#vlan 55
#mtu 9000
If I then do a "sh ip int vlan 55" it reports MTU as 1500, if I do "show vlan" it shows vlan 55 mtu as 9000, Do I need to set the system mtu to 9000 as well? If I set the system MTU to 9000 will that adversely affect the other vlans carrying network traffic with the mtu of 1500? What's the best way to do this?
Thanks, Peter

 

[vipergg]

You need to apply the MTU to the actual switchports not the layer 2 vlan . When yoo do a show ip int vlan 55 that is looking at the SVI . Apply to the switchports and look at it again.

 

[PHerrin]

Thanks vipergg, I have applied the MTU to the interface and now it reports the 9000 MTU, If I apply this to an interface that has a host running data with MTU of 1500 will that impact the communication?

 

[baddos]

Only if you are trying to send that host large frames.

 

[VinceWhirlwind]

Whaqt is the relationship on 4500s between System MTU and interface MTU? Does one supersede the other? ie, having his physical interfaces with an MTU of 9000, but a system mtu with 1500, what happens?

 

[vipergg]

How to configure and explanation .

http://www.cisco.com/en/US/docs/swi...sga/configuration/guide/sw_int.html#wp1068699