scope:

This standard specifies the Packet Services portion of Station Management-2 (SMT-2-PS) for the Fibre Distributed Data Interface (FDDI).

FDDI provides a high bandwidth (100 megabits per second) general purpose interconnection among computers and peripheral equipment using optical fibre or copper twisted pair as the transmission medium in a ring configuration. FDDI can be configured to support a sustained transfer rate of approximately 80 megabits (10 megabytes) per second. The use of dual attachment stations with dual MACs allows these rates to be doubled under the circumstance of a fault-free FDDI ring.

FDDI establishes the connection among many stations (nodes) distributed over distances of several kilometers in extent. Default values for FDDI were calculated on the basis of 1000 physical connections and a total fibre path length of 200 kilometers.

The basic FDDI is defined as an FDDI network when no HRC entities, and thus no isochronous services, are present. The basic FDDI consists of:

a) A Physical Layer (PL), which provides the medium, connectors, station bypassing, and driver/receiver requirements. PL also defines encode/decode and clock requirements as required for framing the data for transmission on the medium or to the higher layers of the FDDI. For purposes of the SMT standard contained herein, references to the PL are made in terms of the Physical Layer Protocol (PHY) and the Physical Layer Media Dependent (PMD) entities which are the upper and lower sublayers of PL, respectively.

b) A Data Link Layer (DLL) which controls the accessing of the medium and the generation and verification of frame check sequences to assure the proper delivery of valid data to the higher layers. DLL also concerns itself with the generation and recognition of device addresses and the peer-to-peer associations within the FDDI network. For purposes of the SMT standard contained herein, references to the DLL are made in terms of the Media Access Control (MAC) entity which is the lowest sublayer of DLL.

c) A Station Management (SMT) standard which provides the control necessary at the station (node) level to manage the processes underway in the various FDDI layers such that a station (node) may work cooperatively as a part of an FDDI network. SMT shall provide services such as connection management, station insertion and removal, station initialization, configuration management, fault isolation and recovery, communications protocol for external authority, scheduling policies, and collection of statistics.

ISO/IEC 9314-27, ISO/IEC 9314-28, and ISO/IEC 9314-29 specify FDDI n-layer management services suitable for nodes and networks that contain HRC entities, commonly referred to as FDDI-II networks.

ISO/IEC 9314, parts 27, 28, and 29 (SMT-2) comprise an enhanced version of ISO/IEC 9314-6 (SMT) which provides the additional services necessary to support stations that contain a hybrid ring control (HRC) entity. HRC also requires that enhanced versions of PHY and MAC, designated PHY-2 and MAC-2, be used in conjunction with it. SMT-2 includes the services necessary to support the isochronous services provided by the isochronous MAC (I-MAC) that is included in HRC.

Since SMT was already a large document and the added isochronous services would add to it considerably, SMT-2 has been organized to consist of three separate documents as follows:

a) The SMT common services (SMT-2-CS), ISO/IEC 9314-27 or ANSI X3.257-1997, that are required to configure an FDDI topology and produce a common channel that can be used to provide both packet services and isochronous services.

b) The SMT packet services (SMT-2-PS), ISO/IEC 9314-29 or ANSI X3.259-1997, that are required to manage a packet media access controller (MAC) that provides a packet channel service to users such as LLC and systems management.

c) The SMT isochronous services (SMT-2-IS), ISO/IEC 9314-28 or ANSI X3.258-1997, that are required to manage an isochronous media access controller (I-MAC) that provides isochronous channel service to circuit-switched users such as a CS-MUX.

This standard specifies the Packet Services portion of Station Management-2 (SMT-2-PS) for FDDI.

SMT-2 also allows operation of FDDI nodes and networks operating in basic mode. Basic mode provides backward compatibility with FDDI nodes operating with only packet transmission (i.e. without isochronous data services). Stations conforming to SMT-2 will interoperate with stations conforming to SMT, when the network is operating in basic mode.

The definition of SMT-2-PS as contained herein includes the set of services that it provides for, and receives from the other entities that are contained within a node. Within SMT-2 resides both knowledge of the uniqueness of this node and the current network structure to the extent that this node's function is affected.

The set of International Standards for FDDI, ISO/IEC 9314, specifies the interfaces, functions and operations necessary to ensure interoperability between conforming FDDI implementations. This standard is a functional description. Conforming implementations may employ any design technique that does not violate interoperability.