Experimentation on the concentrator tree with loopback

The fiber distributed data interface (FDDI) concentrator tree topology with loopback is proposed for use in networks which need to continue operation after multiple faults. Initial experiments to use the concentrator tree with loop-back result in configurational dependencies which are not initially understood. A few caveats are found which can be handled through careful cabling. Both a theoretical and an experimental analysis of various cases of the concentrator tree with loopback are provided. A discussion on the use of bypass relays in the concentrator tree with loopback is given.