Abstract: Methods and apparatus are set forth for utilizing the restricted token operations on an FDDI network. Two service primitives are defined to facilitate the control of restricted dialog. The first defines what class of token can be captured for the purpose of transmitting asynchronous data. Secondly, a primitive is defined for use at the end of each transmit request to give control over the token type that will be issued at the end of a given transmission. A hardware protocol is defined which provides reliable control over these two parameters, together with methodology for linking frames in a buffer memory during restricted operation. The combination of the hardware protocol and methodology allows restricted dialog to be realized without real-time software interaction.

Abstract: A modular system for configuring and reconfiguring the data paths within a local area network station permits the network station to be configured in various operational modes including a through mode, a wrap mode, and a concentrator mode. A module includes a media access controller MAC and an encoder/decoder ENDEC connected together by a bus. Certain signals from the bus are selected by a multiplexer. External signals for example, from another module are inputted to the bus through a latch. The multiplexer and the data paths through the MAC and ENDEC are controlled to configure the station in one of the operational modes. A second module similar to the first module is used to provide a station for a dual-ring local area network conforming to the FDDI standard.

Abstract: A method and appartaus are disclosed for preserving a minimum or maximum interpacket gap length in an independently clocked data network, typically one following the ANSI-FDDI standard. A smoother is placed downstream of each elastic buffer in the network. The smoother detects the occurrence in an arriving stream of bytes of short preambles, i.e., those having fewer than a threshold number of idle bytes, and inserts some number n.sub.a additional idle bytes into such preambles. Subsequently arriving bytes are delayed by n.sub.a byte clock periods by, in a preferred embodiment, storing them in a FIFO sequence of registers. In order to be available for lengthening other short preambles when they arrive, the smoother also detects the arrival of long preambles, i.e., those having more than the threshold number of idle bytes, and deletes a number n.sub.d idle bytes from such long preambles.