I've had pretty good luck asking for higher MTU's on both customer and peering links. I'd say about an 80% success rate for dedicated
GigE's.
It's generally not on the forms though, and sometimes you get what I consider weird responses. For instance I know several providers who won't going higher than 4470 on ethernet.
If more folks asked for higher MTUs it might become part of the standard forms...
That is what I am thinking as well. For example, in the past week I have seen someone here asking about data center locations and mentioned data replication between them. If you are on both coasts of the US and are backing up or otherwise replicating data between the two, even going to a MTU of 3000 is a measurable win depending on the amount of data you are moving and the protocols you are using. Load on routers and even hosts is generally caused by packets per second, not bits per second. If you cut the number of packets in half you reduce the load on every single piece of gear in the path. Gee, I wonder how much energy consumption that would save on a global basis if everyone did that. Coming across Phil Dykstra's paper from 1999 is what got me thinking about it (well, that and moving a lot of data between Europe and the West coast of the US). http://sd.wareonearth.com/~phil/jumbo.html http://staff.psc.edu/mathis/MTU/