Jumbo frames aside from the usefulness of bigger payload for mpls/tunnels etc add some value in an environment where there's some packet loss.

For example in an environment with say a 1Gbps link where packet loss is .1% with 1500 byte MTU you get 28Mbps througput. With Jumboframes that leaps to approx 162Mbps.

Of course bandwidth delay product and default TCP window sizes will catch you well before that. It's probable that your link delay will be greater than 20-30ms before the internetworking is complex or twisty enough so that packet loss is happening (assuming there's a correlation between complex paths and loss (which there usually is).

Aside from that, not much.

Jamie



On Wed, 2007-03-28 at 15:01 +1200, Ian Batterbee wrote: 
Has anyone got any real world experience of the usefulness of jumbo 
frames on ethernet (ie, MTU > 1500 bytes). A number of 1000mbps 
interfaces support it, but it seems to be that it would only be useful 
if jumbo frames were supported and enabled on all equipment between the 
sending NIC and final IP destination, so I'm struggling to see how 
enabling it in just say the core of a network would be all that helpful.



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