FDDI
The FDDI standard describes a network that can span up to 100 kilometers (62 miles) over single-mode fiber optic cabling.
The transmission rate on a FDDI network is typically 100 MBPS over multimode cable.
FDDI allows up to 500 devices per network.
The FDDI network has two rings, the primary ring and the secondary ring. Data travels on the primary ring.
The secondary ring is used as a backup, in case the primary fails.
However, if the secondary ring is not used for backup, it can increase the effective transmission rate can be doubled.