International Business Machines Corporation

Lee C Haas

Kenneth J Christensen

Francis Edward Noel, Jr

Mitchell Levy Loeb

David E Conner

Paul Abramson

George R Stillwell, Jr

Disclosed is a method of transmitting ATM cells from a sending unit to a receiving unit on an ATM link wherein each of the ATM cells includes a header portion and a data portion. In the sending unit, a header portion is identified which is common to a set of subsequent ATM cells. Then, the common header portion is transmitted from the sending unit to the receiving unit followed by all data portions of the set of subsequent ATM cells. In the receiving unit, the original set of subsequent ATM cells is generated by using the common header portion.

Method and system for transmitting ATM cells on an ATM link

Data capacity mismatches between a communication node, including end node work stations, and a communication link usually require large buffer storage to prevent the loss of transmitted data frames due to transmission of an incomplete frame. Transmitted data frame continuity is maintained in the present invention by using small FIFO buffers in the node to store small portions of a data frame as data is sent and received. In addition, the data frame is maintained by stretching the transmitted frame on the link when necessary to prevent loss of the frame and compress the stretched frame when it is received from the link. The stretching and compressing is accomplished by inserting and removing non-data symbols, or command code words, in the transmitted and received string of data words. Small FIFO buffers (much less than a data frame in data capacity) operate on the fly to transmit and receive data without requiring contiguous transmission of a complete frame. At the sending node, non-data symbols are inserted in the frame between data words to fill gaps between strings of data bytes. At the receiving node, the non-data symbols are stripped from the received data frame to separate non-data symbols from data bytes. The non-data symbols are encoded command code words used to communicate status between the transmitting node and the receiving node. Transmitted encoded commands convey to a receiving node the status information of the transmitting node. The commands include Ready and Busy to indicate to the node at the opposite end of the link the status of the receive FIFO buffer in the node sending the commands.

Preserving data frame continuity across full-duplex LAN interface with

This invention relates to 'clear pipe' communication networks meaning the nodes and links handle a variety of data frame types depending on their communication protocols such as Token Ring, Ethernet, FDDI or ATM. More particularly, this invention relates to node/link interface adapters at nodes which include switching nodes and end nodes. The adapters identify data frame type and adapt the node/link adapter operative elements to handle the various types of data frames as they travel through the network. The invention identifies the frame type at the source, flags the frame type to the nodes by use of unique SDEL (start delimiter) symbols or codes, uses the SDEL codes as received with the frame at each node to find the destination address in the frame and to adjust the transmission rate for the frame. The transmission rate is adjusted by inserting null non-data symbols in the frame to effectively slow the data rate to the data rate capacity of the protocol.

Adapting switch port and work station communication adapters to data

A system and method for encoding and decoding binary data for serial transmission over a physical medium provides a highly efficient and less complex coding scheme while guaranteeing clocking information and guaranteeing an NRZ(I)-disparity of no greater than one per five-bit word. The system and method of the present invention comprise a 4/5 encoder which enables each nibble to be encoded and decoded independently from one another. The Coding system and method of the present invention guarantees an NRZ(I)-disparity having a magnitude of no greater than one for any word after NRZ(I) while providing at least one word with 'NRZ(I) comma' property.

Method and apparatus for providing data stream for cost effective

A system and method for encoding and decoding binary data for serial transmission over a physical medium provides a highly efficient and less complex coding scheme while guaranteeing clocking information and guaranteeing an NRZ(I)-disparity of no greater than one per five-bit word. The system and method of the present invention comprise a 4/5 encoder which enables each nibble to be encoded and decoded independently from one another. The coding system and method of the present invention guarantees an NRZ(I)-disparity having a magnitude of no greater than one for any word after NRZ(I) while providing at least one word with 'NRZ(I) comma' property.

Described is a circuit arrangement which reduces intersymbol interference among pulses in a fiber optic communications network. The circuit arrangement includes a wavelength separator which separates each pulse into a plurality of sections which are shifted in time and then realigned relative to its center section to form non-overlapping pulses.

Reduction of intersymbol interference in optical fiber systems by

The multiplexing circuit disclosed herein combines multiple input signals into a common output by allowing ternary signals to pass from multiple input circuits to a common output circuit. The circuit combines ternary signals with minimum feedback between input circuits. The circuit is passive, has minimum attenuation, and a small number of components.

Ternary signal multiplexor circuit

When a byte of digital data is transmitted through a dispersive medium using frequency or wavelength division multiplexing (WDM) techniques, individual bits in the byte are normally delayed different amounts of time. This is referred to as bit skew. WDM apparatus is described along with a system for deskewing WDM data received after transit through a dispersive medium. Two bits in a given byte of data are detected. The relative times of arrival of the remaining bits in a byte are predicted using the relative delay between the two detected bits and the known frequency-related dispersion characteristics of the transmission medium. Certain bits in each received byte may be delayed using clock delay lines or registers to reduce the amount of time skew between the various bits in a byte.

Growing community of inventors

Raleigh, NC, United States of America

Lee C Haas