This is a general question directed to the operators of NAPs or IXs. If
company X buys a port, but wants to buy another port for backup purposes, is
the 2nd port offered at the same cost, or at a reduced cost?
Depends which XP...
Sprint (Pennsauken) homes people to "both" gigaswitches, but only lets
you have one router anyway - so if you wanted another port to keep live
with a 2nd IP, you'd have to put two routers in.
Anyway, Sprint/Psk, and MFS with MAE-East and MAE-West charge full price
for additional ports (don't really have the concept of a backup port price)
as far as I know.
PacBell and Ameritech may be different, since there's a "NAP fee" but if
you put a 2nd ATM port into their cloud, they might not charge you anything
extra to run PVCs into it for backup peering.