Specifying the physical layer in a LAN standard: a comparison of CSMA/CD and token ring

The author examines the differences between the physical layers of the IEEE 802.3 CDMA/CD (carrier-sense multiple access with collision detection) and IEEE 802.5 token-ring LAN (local area network) standards. He reviews the specific requirements n 802.3 for coaxial 10Base5 transmission and relates the physical requirements to performance requirements for the system. He also describes the differences between the physical layer specifications needed for the two LAN standards. A point-by-point comparison of the major physical specifications for 802.3 (10Base5) and 802.5 is made to show why the specification for the 802.5 physical layer can be done more simply than for 802.3. In addition, the 802.5 physical layer is examined to clarify the role of jitter building, automatic lobe checking, and the time required to enter the ring