I know of plans for at least 2 exchanges that will use 100baseTx
as a connection option. The only real problem is
the backplane limit of boxes that switch 100baseTX,
(Cisco Cat 5000, 1.2gbps). This is only slightly
better than the Dec Gigaswitch limit of 800mbps.
DEC Gigaswitch is actually a 3.6Gb/s switch
Ye olde trick aggregate bandwidth answer. I know that one.