摘要： 本文介绍一个用光纤作为介质的令牌传递环形局部网的实现,着重描述了环网适配器的硬件结构与 功能。包括其主要的构成模块、如何实现最大的操作并行性、帧格式、在帧中用进程名代替地址以增加 灵活性、立即捎带确认的实现以及令牌的维护等方面。说明了适配器与主机的接口,包括主机可使用的 命令集以及正常操作结束或出错时通过中断向主机提供的状态报告。这组丰富而灵活的命令和状态报告 便于高层软件的开发。最后简单地介绍了通过UNIX BSd 4.2版操作系统提供的网络高层软件,用本适 配器连接VAX 11/750构成一个环网的体系结构。

Abstract: This paper presents the implementation of a token-passing ring local area network which uses optical fiber as transmission medium. First, the hardware and the function of the ring adaptor are described. Main hardware moduls, maximizing parallel of ope-raions, frame format, using process name instead of host address, immediately piggybacking acknowledgement and token maintainace are included in the description. Then the interface between ring adaptor and host is introduced. The ring adaptor provides host with a set of commands and status reports which are very flexible and useful for developing high layer network software. Finally the architecture used in the ring network which connects two VAX 11-750 machines is given in brief. The high layer network software is adapted from UNIX Bsd 4.2 operating system.