Communication control method and equipment for implementing the same

A communication control equipment used for ATM communication including a transmission system adapted so that data cell sent from an ATM layer control unit is inputted thereto to convert the data cell into frame data to transmit the frame data to transmission line, a receiving system adapted so that frame data sent from the transmission line is inputted thereto to convert the frame data into data cell to transmit the data cell to the ATM layer control unit, and a loop-back line or circuit for carrying out loop-back of the data cell inputted to the transmission system to deliver the data cell to the receiving system,

• wherein the transmission system comprises
• a transmission cell interface operative so that when data cell is inputted thereto, the transmission cell interface generates a valid cell flag signal indicating that valid data cell exists to output the valid cell flag signal along with the data cell, and to generate and output a cell byte count signal for counting the number of bytes of cell to be outputted, and
• a transmission cell processing section operative to generate idle cell and test cell to select any one of the data cell, the idle cell and the test cell on the basis of the valid cell flag signal and a test cell sending start signal inputted from the external to output selected one in accordance with the cell byte count signal,
• wherein the transmission cell processing section includes
• an idle cell generating circuit for generating and outputting idle cell in accordance with the cell byte count signal,
• a test cell generating circuit supplied with data related to test purpose from the external to generate test cell including this data to output the test cell in accordance with the cell byte count signal,
• a selector control circuit operative to generate a select signal to select the data cell when the valid cell flag signal is delivered thereto, to select the test cell when the valid cell flag signal is not delivered thereto and the test cell sending start signal is delivered thereto, and to select the idle cell when both the valid cell flag signal and the test cell sending start signal are not delivered thereto, thus to output the select signal, and
• a selector for selecting any one of the data cell, the idle cell and the test cell on the basis of the select signal to output selected one.

A communication control method for ATM communication in which data cell sent from an ATM layer control unit is inputted to a transmission system to convert the data cell into frame data to transmit the frame data to transmission line, and frame data sent from the transmission line is inputted to a receiving system to convert frame data into data cell to transmit the data cell to the ATM layer control unit, thus to allow data cell inputted to the transmission system to undergo loop-back to deliver data cell to the receiving system,

• wherein, in the transmission system, the method comprises
• generating and outputting idle cell, and
• generating and outputting test cell,
• whereby when data cell sent from the ATM layer control unit is delivered, the data cell is outputted, when output of test cell is designated and no data cell exists, the test cell that the test cell generating circuit outputs is outputted, and when no data cell exists and output of test cell is not designated from the external, the idle cell that the idle cell generating circuit outputputted.

A communication control method for ATM communication in which data cell sent from an ATM layer control unit is inputted to a transmission system to convert the data cell into frame data to transmit the frame data to transmission line, and frame data sent from the transmission line is inputted to a receiving system to convert frame data into data cell to transmit the data cell to the ATM layer control unit, thus to allow data cell inputted to the transmission system to undergo loop-back to deliver the data cell to the receiving system,

• wherein, in the transmission system, the method comprises
• a first step of generating, when data cell is inputted thereto, a valid cell flag signal indicating that valid data cell exists to output the valid cell flag signal along with the data cell, and generating a cell byte count signal for counting the number of bytes of cell to be outputted to output the cell byte count signal, and
• a second step of generating idle cell and test cell to select any one of the data cell, the idle cell and the test cell on the basis of the valid cell flag signal and a test cell sending start signal delivered from the external to output selected one in accordance with the cell byte count signal,
• wherein the second step includes
• a step of generating idle cell to output the idle cell in accordance with the cell byte count signal,
• a step of being supplied with data related to test purpose from the external to generate test cell including this data to output the test cell in accordance with the cell byte count signal,
• a step of generating a select signal to select the data cell when the valid cell flag signal is given, to select the test cell when the valid cell flag signal is not given and the test cell sending start signal is given, and to select the idle cell when both the valid cell flag signal and the test cell sending start signal are not given, thus to output the select signal, and
• a step of selecting any one of the data cell, the idle cell and the test cell on the basis of the select signal to output selected one.