Inter-exchange media types

A new stdaddr draft is forthcoming shortly. This other conversation is of
interest, though. We're arguing about 100Mb/s interconnect technology as
if we all planned to keep using it for some significant period. That's not
so. Two years from now it'll be 622Mb/s or it'll be a dead concept. PMTUD
matters, and TCP MSS (therefore IP MTU) matters because it will dictate the
frame rate to the routers and the end hosts. Bytes are cheap, frames cost.