It is well known that the 21st century will be an information age.People are increasingly looking for high capacity long distance communication systems.The optical networks are the most important technological pillar of the information society.Fiber Distributed Data Interface FDDI networks is an optical communication system which use optical fiber as a transmission media for long haul networks. The use of optical fiber solves the problems resulted from the electromagnetic interference EMI, noise, and attenuation problem related to other transmission media. In addition, it increases the security of transmission. This work presents the basic principles and concepts including the design of optical fiber link including the power budget and rise time budget. The structure of FDDI network including network layers with details is introduced . A design and Implementation of a ring network which utilizes FDDI technique is introduced in this book with performance criteria investigation to decide the reliability of the proposed system.