Jumbo Frames question

[weiler]

Greetings all!

Question about jumbo frames on a bunch of 3750s we have. I understand that if we want to enable 9000 byte jumbo frames, we need to make sure all 100Mb and 10Mb devices need to be removed from the switches.

What I don't quite understand is: Do we need to actually remove all the 10/100 devices from all the physical switches that are uplinked to each other, or just remove the 10/100 devices on the *vlan* we want to enable jumbo frames on?

i.e. if we have 10 switches, and one of those switches has 2 vlans on (vlan 1 and vlan 2), and the other 9 switches just have vlan 1, would a 10/100 device on vlan 2 mess it up for the rest of the vlan 1 switches?

To rephrase: Do ALL switches on one side of the router need to use jumbo frames, or just certain VLANs?

Thanks for any insight!

[owillins]

Jumbo frame support can be enabled on the following types of interfaces:

port-channel interface

Switched Virtual Interface (SVI)

physical interface (L2/ Layer 3 (L3))

http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a00801350c8.shtml

[Edison Ortiz]

Jumbo Frames are enabled globally on the Catalyst switch with the system mtu command

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_40_se/command/reference/cli3.html#wpmkr2357471

and affects all interfaces and Vlans on the switch.

If you decide to enable Jumbo Frames, it's recommended to enable it in all switches as packet may be fragmented when it hits a switch w/o Jumbo Frame enabled.

HTH,

__

Edison.