Jumbo Frame Support

Unanswered Question
Nov 13th, 2007

We have an app server that is capable of supporting Ethernet frames up to 6K or so. Currently, it has redundant connections to a pair of Cat 4506 (Sup IV, IOS 12.2(25)EWA5) on 10/100/1000 48-port line cards. Both switches have a pair of Gig fiber trunks uplinked to redundant 6509 core switches (Sup 2,IOS 12.2(18)SXF3.) I have reviewed Cisco's documentation on enabling jumbo frame support on these switches, but on how many interfaces would I need it configured? The two interfaces on the 4500 switches are a given, but does it also need to be set on all the aforementioned trunked interfaces? Or does this have to be applied to nearly all datacenter switches, similar to uplinkfast/backbonefast commands?

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azoulflak Tue, 11/13/2007 - 08:52

I think you need to enable jumbo frame on all components located on the data path.

if any component in the data path is limited to a 1500 byte MTU the data path will not support Jumbo Frames.

Deployment scenarios of jumbo frame:

· Server-to-Server

· Server-to-Switch

. Switch-to-Switch

. etc ..

keller.oliver Tue, 11/13/2007 - 22:51

Although my opinion is theoretical, I'd say it would be better to either have a complete jumbo frame connection or none at all.

If the server-switch connection features jumbo and the rest doesn't, then the switch has to care for segmenting/fragmenting the jumbos into standard size frames. This may take some load off the server, but puts the load directly on the switch.

But I may be corrected here :).

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