A Synchronous Fiber Optic Ring Local Area Network for Multigigabit/s Mixed-Traffic Communication

Abstract

A synchronous-ring fiber optic local area network is reported that facilitates the simultaneous transmission of packet and real-time traffic at gigabit/s rates, minimizes the amount of high-speed logic, and simplifies the user interface to the network. The novelty of the technique is based on 1) suspending in transit around the ring's circumference an integral number of data frames and 2) achieving this condition by skewing the frame clock rate a small amount ( < 1 percent). Rather than use the whole data frame as one packet destined to a specific user (as in a slotted ring), we instead time multiplex many individual channels into the data frame. This technique only becomes feasible for local networks as data rates approach the Gbit/s range. This departure from other synchronous rings results in several advantages both in terms of system performance and hardware simplicity.