Design and implementation of an ATM backbone ring

The Cambridge Backbone Ring project has designed and built an experimental ring communication network for computer data and real-time applications. The network forms a backbone facility for interconnecting groups of CFR (Cambridge Fast Ring) networks and Pandora multimedia workstations in the Cambridge area. Access control uses the empty slot protocol, using short, fixed-length cells which contain 32 bytes of payload and a 4-byte header containing the virtual circuit identifier. Although the architecture was designed for line rates of 1 Gb/second and higher, the current implementation operates at 512 MHz. Twenty-five stations have been constructed to date. A revision incorporating the now-standard, 48-byte cells and operating at a higher line rate is planned.<>