Fiber Distributed Data Interface (FDDI, ~802.5)
fibre optic token ring LAN
- 100 Mb/ s, up to 200 km distance
- 1,000 stations allowed
- max of 1 error in 2.5 x 10**10 bits allowed
can be used as backbone to connect together multiple lower speed LANS
- in a big network, several frames may fit on ring at same time
- if wait for frame to come 'round before regenerating token, bandwidth wasted
- instead, token regenerated after frame sent