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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。
This article describes an implementation of a token-passing ring local area network using optical fibers as a medium, highlighting the hardware structure and functionality of the ring network adapter. Including its main constituent modules, how to achieve maximum operational parallelism, frame formats, replacing process addresses with addresses in the frame for added flexibility, immediate piggybacking, and token maintenance. Describes the interface between the adapter and the host, including the set of commands that the host can use and the status reports provided to the host via interrupts at the end of normal operation or in the event of an error. This rich and flexible set of commands and status reports facilitates the development of high-level software. Finally, a brief introduction to the network high-level software provided by the UNIX BSd 4.2 operating system, using this adapter to connect the VAX 11/750 to form a ring network architecture.