At the Atlanta-NAP we offer full duplex FDDI, why not try to get MFS to do it? Cisco now has a full duplex FDDI card, so you can do 200 Mbs into the NAP.
Every NAP with a GIGAswitch/FDDI offers full duplex FDDI; the MAEs, Sprint, PAIX, and you. Buy a full-duplex-capable card, install it, and you get full duplex. You, the NAP operator, do nothing; the devices negotiate in and out of full duplex mode themselves. I'm somewhat confused as to why you would say you offer full duplex FDDI in a manner that implies no-one else does. If someone walked up to your GIGAswitch/FDDI (or anyone's) with a full duplex line card, they'd get full duplex unless you took some specific action to prevent it (by, say, putting three stations on a ring), or if you disable it in management (it comes enabled by default).
From Chapter 1 of the Big Book of GIGAswitch/FDDI (June 1993):
"Point-to-point links can operate in a full-duplex mode to increase bandwidth and reduce latency. Using FDDI, simultaneous transmission and reception in a point-to-point connection between two FDDI adapters that support full-duplex communication can provide twice the raw bandwidth of the data link. When a point-to-point link is created with a station that can use full-duplex mode, the communication mode is changed from token ring to full-duplex. No token is passed in full-duplex mode. Configurations can automatically move in and out of full-duplex mode as the opportunity (two stations on a ring, both capable) becomes available, or unavailable. Full-duplex mode can be disabled using MIB objects in version 2.7 of the DEC Vendor MIB." Since you point it out as a specific offering, does that mean you turn it off by default? Do you charge more for it? Stephen