Technology Basics3-18Fiber Distributed Data InterfaceTroubleshooting: In the event that an FDDI network undergoes a failure, thenetwork will literally bend over backwards in an effort to keep the networkoperating. The exceptionally fast reaction time on station and ring wrapping healsthe FDDI network almost instantly. Multiple faults in the network will eventuallybe isolated by the normal operation of the technology. This may sometimes leadto some unusual network conditions, but the network will try to remainoperational at any cost. Once trouble segments have been located, the relativescarcity of FDDI troubleshooting devices may increase the time needed todiagnose and deal with a problem.Cost: FDDI is expensive. In part due to the complexity and sophistication of thedevices used and in part due to the relatively small installed base of FDDInetworks, FDDI networking hardware remains among the most expensive in thenetworking industry. In conjunction with the expense involved in installing andpurchasing fiber optic cabling, the default media for FDDI connections, FDDI iseasily the most expensive standardized technology addressed in this NetworkingGuide. This added expense often relegates the FDDI technology to the corporateor facility backbone network, supplying interconneciton for slower workgroupLANs.Special Design Considerations• FDDI operates like Token Ring, but faster.• The technology, designed to use the very noise-resistant fiber optic media,supports very long distances and a large number of stations.• There are generous maximum limitations to the number of stations on a ringand the maximum length of an FDDI cable.• FDDI is expensive when compared to other networking technologies, and isoften used initially as a backbone technology.
