IEEE Standards for Local Area Networks: Token Ring Access Method and Physical Layer Specifications

This standard specifies the formats and protocols used by the Token-Passing Ring medium access control (MAC) sublayer, the physical layer, and the means of attachment to the token-passing ring physical medium. IEEE Std 802.5-1985 will aid in the compatible interconnection of data processing equipment by way of a Local Area Network using the token-passing ring access method. This document defines the frame format, including delimiters, addressing and frame check sequence, and introduces timers, frame count, and priority stacks. It also defines the medium access control protocol and provides finite-state machine and state tables supplemented with descriptions of the algorithms. It describes the services provided by the medium access control (MAC) sublayer to the network management and the logical link control sublayer and the services provided by the physical layer to network management and the MAC sublayer. These services are defined in terms of service primitives and associated parameters. Also defined are: the physical layer functions of symbol encoding and decoding, symbol timing and latency buffering; and, the 1 Mb/s and 4 Mb/s shielded twisted pair attachments of the station to the medium.