National Semiconductor Corporation

Cisco Technology, Inc.

Walter R Friedrich

Shantanu Sarkar

Luke K Surazski

Keith A Lantz

Duanpei Wu

Scott S Firestone

James R Hamstra

Nermin M Ismail

David C Brief

James F Torgerson

A physical layer controller for use in a data transmission network is disclosed which includes an automatic scrubbing arrangement that is activated upon the occurrence of a physical layer controller reconfiguration. The transmitter output port as well as each channel output of the physical layer controller has an output dirty flag associated therewith. Similarly, the input port as well as each channel input has an associated input dirty flag. A scrubbing arrangement automatically scrubs certain outputs after a configuration change. More specifically, in the absence of a blocking condition after a configuration change, the scrubbing arrangement will automatically scrub each output which has a new source and one of: 1) its associated output dirty flag is set to a first level; and 2) it is connected to an new source which has its associated input dirty flag set to a first level. In a method aspect, output dirty flags are set for each output that has the potential to transmits a data frame. Outputs which have data frame detection available are considered to have the potential to transmit a data frame only when they sense a frame start. Outputs that do not have data frame detection available, are considered to have the potential of having transmitted a data frame anytime they are enabled and coupled to a valid input. The input dirty flags are set for each input that is connected to an output for which the output dirty flag is set.

System for physical layer controllers for performing automatic hardware

A controllable physical connection management (PCM) pseudo code user interface is disclosed for use in the physical layer controller of a station or concentrator that is capable of insertion into a data transmission network that is capable of operating substantially in accordance with the FDDI protocol. In one aspect of the invention, the interface permits the user to direct the PCM state machine to pause after entering the Next state after the transmission of any pseudo code signalling bit. In another aspect of the invention, the interface permits a user to load a hardware register with the pseudo code signalling information to be transmitted before the signalling begins. However, Complete control of the pseudo code signalling is retained by the user during the signalling process to permit midstream changes in the pseudo code sequence to protect against communications with unexpected neighboring port configurations and to permit custom pseudo code signalling sequences.

PCM pseudo code signalling user interface

A controllable configuration management (CFM) state machine user interface is disclosed for use in the physical layer controller of a station or concentrator capable or insertion into a data transmission network that is capable of operating substantially in accordance with the FDDI protocol. In one aspect of the invention, the physical layer controller includes a null configuration register, a join configuration register and a loop configuration register. The null configuration register is capable of storing information indicative of a desired configuration of the physical layer controller when the CFM state machine is in a null configuration. Similarly, the join and loop configuration register are capable of storing information indicative of desired configurations when the CFM state machine is in the join and loop configurations respectively.

FDDI configuration management state machine controller

A controllable physical connection management (PCM) state machine user interface is described for use in the physical layer controller of a station or concentrator capable of insertion into a data transmission network that operates substantially in accordance with the FDDI protocol. In one aspect of the invention, the interface permits the user to direct the PCM state machine to pause after entering a particular state during the initial connection management sequence. In another aspect of the invention, the interface permits a user to force a state transition by writing the desired new state into a state register. These user interface features allow the state transitions to be controlled by the user and therefore possibly changed. In a preferred embodiment, the user initiated state transition can occur while the PCM state machine is paused.

Controllable PCM state machine user interface

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Pleasanton, CA, United States of America

Walter R Friedrich