scope:

This FDDI standard specifies the Physical Layer Repeater Protocol (PHY-REP) for the upper sublayer of the FDDI Physical Layer.

FDDI provides a high-bandwidth (100 Mbit/s), general-purpose interconnection among information processing systems, subsystems, and peripheral equipment, using fibre optics or other transmission media. FDDI can be configured to support a sustained data transfer rate of at least 80 Mbit/s (10 Mbyte/s). FDDI provides connectivity for many nodes distributed over distances of many kilometers in extent. Certain default parameter values for FDDI (e.g., timer settings) are calculated on the basis of up to 1 000 transmission links or up to 200 km total fibre path length (typically corresponding to 500 nodes and 100 km of dual fibre cable, respectively); however, the FDDI protocols can support much larger networks by increasing these parameter values.

an FDDI repeater consists of:

a) A Physical Layer (PL), which is divided into two sublayers:

1) A Physical Medium Dependent (PMD), which provides the digital baseband point-to-point communication between nodes in the FDDI network. The PMD provides all services necessary to transport a suitably coded digital bit stream from node to node. The PMD defines and characterizes the fibre-optic drivers and receivers, medium-dependent code requirements, cables, connectors, power budgets, optical bypass provisions, and physical-hardware-related characteristics. It specifies the point of interconnectability for conforming FDDI attachments. The initial PMD standard defines attachment to multi-mode fibre. Alternative PMD sublayer standards are defined for attachment to other transmission media.

2) A Physical Layer Repeater Protocol (PHY-REP), which provides PMD to PMD connectivity. PHY-REP provides the necessary modifications to the PHY standard (ANSI X3.148-1988) for repeating the signal from one PMD to another. The definition of PHY-REP is contained in this standard.

b) A Station Management (SMT), which provides management access to the Physical layers. This entity allows the repeater to be reset and controlled by a node processor.

The definition of PHY-REP as contained in this standard is designed to be as independent as possible from the actual physical medium.

Implementations that conform to this standard shall also be interoperable with implementations that conform to ISO 9314-1: 1989 (ANSI X3.148-1988 and X3.284-1994) if the additional capability of Hybrid mode operation (as defined in this document) is not being used. Implementers are encouraged to read ISO 9314-1 or ISO 9314-7 in addition to this standard.

The set of FDDI standards specifies the interfaces, functions, and operations necessary to ensure interoperability between conforming FDDI implementations. This FDDI standard on PHY-REP is a functional description. Conforming implementations may employ any design technique that is interoperable.