Whether it be for the World Wide Web or for an intra–office network, today’s businesses and services are heavily dependent on the telecommunications infrastructure. Computers and networks are inextricably linked in business today. Just as processors have increased their speed in instructions persecond, users have demanded more bandwidth in megabits to gigabits per second from their networks. Many high–speed technologies have emerged or are emerging including: FDDI,CDDI, Fast Ethernet, Gigabit Ethernet, and AsynchronousTransfer Mode (ATM). Only ATM has the ability to integrate voice, video, and data over a single medium and requires a great deal of high–speed bandwidth. One of the major ways that switch, router, and hub manufacturers have been able to differentiate their products has been in the fabric and buffer management. The shared or distributed cell or frame fabric as well as the input and/or output buffers determine: