FDDI (Fiber Distributed Data Interface) is a set of ANSI and ISO
standards for data transmission on fiber optic lines in a local
area network (LAN) that can extend in range up to 200 km (124
miles). The FDDI protocol is based on the token ring protocol.
In addition to being large geographically, an FDDI local area
network can support thousands of users. FDDI is frequently used
on the backbone for a wide area network (WAN). An FDDI network
contains two token rings, one for possible backup in case the
primary ring fails. The primary ring offers up to 100 Mbps
capacity. If the secondary ring is not needed for backup, it can
also carry data, extending capacity to 200 Mbps. The single ring
can extend the maximum distance; a dual ring can extend 100 km
(62 miles). FDDI is a product of American National Standards
Committee X3-T9 and conforms to the Open Systems Interconnection
(OSI) model of functional layering. It can be used to
interconnect LANs using other protocols. FDDI-II is a version of
FDDI that adds the cap