AS 4802.5-1992

Using the token-passing ring access method on a local area network, This Standard defines the frame format and the medium access control protocol. The services provided by the medium access control sublayer and the services provided by the physical layer sublayer are described. The physical layer functions of symbol encoding and decoding, symbol timing and pair attachment of the station to the medium, including the definition of the medium interface connector, are defined. This Standard is identical with and has been reproduced from ISO/IEC 8802-5:1992.

For the purpose of compatible interconnection of data processing equipment via a local area network (LAN) using the token ring access method, this standard(1) Defines the frame format, including delimiters, addressing, routing information, and frame-check sequence (FCS), to allow operation on a single ring or on multiple rings connected by source routing or transparent bridges, and introduces medium access control (MAC) frames, timers, counters, and priority stacks (see Section 3);(2) Defines the MAC protocol. The finite-state machine and state tables are supplemented with a prose description of the algorithms (see Section 4);(3) Defines the physical layer (PHY) functions of symbol encoding and decoding, symbol timing, and latency buffering (see Section 5);(4) Describes the services provided by the MAC to the station management (SMT) and the logical link control sublayer (LLC) and the services provided by the PHY to SMT and the MAC. These services are defined in terms of service primitives and associated parameters (see Section 6);(5) Defines the 4 and 16 Mb/s, shielded twisted pair attachment of the station to the medium including the definition of the medium interface connector (MIC) (see Section 7);(6) Includes the PICS proforma in compliance with the relevant requirements, and in accordance with the relevant guidance, given in ISO 9646-2 [7]1(see Annex C).The definition of suitable media (twisted pair, coaxial cable, and optical fiber) for connecting stations that meet the attachment standard specified herein is a subject for future consideration. Until such time as these media are specified, the specifications in Section 7 shall define the performance bounds to which an operating network, including media and trunk coupling unit(s) (TCUs), shall conform.A particular emphasis of this standard is to specify the homogeneous externally visible characteristics needed for interconnection compatibility, while avoiding unnecessary constraints upon and changes to internal design and implementation of the heterogeneous processing equipment to be interconnected.The applications environment for the LAN is intended to be commercial and light industrial. The use of token ring LANs in home and heavy industrial environments, while not precluded, has not been considered in the development of this standard.

First published as AS 4802.5-1992.