This study presents a novel window-based token protocol which supports two priority levels of ATM-like bursty traffic. The proposed protocol ensures that packets arriving during a given window period are always transmitted prior to those arriving during subsequent window periods. During which periods, high priority (delay-sensitive) packets are served by a nonpreemptive priority service discipline. Under this window-based token protocol, the delay bounds for packets of both priority levels are derived when the traffic streams satisfy the traffic descriptors. Hence, a call admission control policy based on delay bounds can be employed to guarantee QoS parameters such as the packet delay and packet loss-free requirement for each traffic stream. The protocol proposed herein can achieve tighter delay bounds than the IEEE 802. 5 token protocol and the timed token protocol used in FDDI, particularly for high priority bursty traffic, thereby making it highly attractive for supporting not only real-time multimedia VBR or CBR services such as in ATM networks but also ATM encapsulation such as in Cells In Frames (CIF) protocol.

Three techniques are proposed for reducing the time required for protocol processing: protocol data unit management using page management, assembly and disassembly of data packet header and contents in hardware, and rescheduling of protocol processing. These techniques were shown to be feasible by applying them to the TCP/IP over a fiber-distributed data interface network. The maximum communication throughput was 91.6 Mbps; the total throughput for 64 sessions was 89.6 Mbps, only 2% less than the maximum. These techniques will enable the development of more effcient video-on -demand systems.

The FDDI-II is a high speed and flexible backbone LAN. It can divide the capacity into one packet-switched channel with flexible bandwidth and up to 16 isochronous channels which may be allocated for a variety of real-time services such as video and voice. How to allocate and maintain isochronous bandwidth is an important issue for supporting good services to users. The FDDI-II standard proposed a centralized scheme to achieve this goal. In this paper, we propose a new scheme in a distributed fashion for the management of isochronous bandwidth. Based on our scheme, the network can support various services in a more efficient way.

Fiber-optic local area networks (LANs) with Fiber Distributed Digital Interface (FDDI) protocol have come into use as backbones connecting other small LANs. This paper describes the current status of LANs, reviews a number of issues that stand in the way of further development and look at the future of LANs. Demands for wide-area networks (WANs) connecting LANs and multimedia LANs including voice and image capability has been extremely strong, spurring progress in geographical expansion and throughput increase, now over 100Mbit/s. The logical choice of transmission medium for next-generation systems is single-mode optical fiber, not only for backbone LANs but also, eventually, for floor LANs.