| 摘要 |
<p>PROBLEM TO BE SOLVED: To decrease occurrence of the backward pressure signals and to secure the high cell yield by changing the allowance number of input cells for every input port. SOLUTION: A buffer allowance value control part 15 reads the shared buffer occupation information out of a shared buffer control part 12 to calculate the shared buffer occupation rate of every input port and the input port allowance value at each W cell time of an allowance value rewriting interval, sends these calculated rate and value to the part 12, and generates the control signal to decide every priority class buffer allowance value. A unit switch has N pieces of input port occupation information tables at the part 12 to store the occupation information on N pieces of input ports and stores the cell number Li of the relevant input port in the t-th table. When the number of bells of a shared buffer 11 is equal to its allowable value t1 , a backward pressure signal is generated to inhibit the cells which are inputted from an i-th input port. That is, the part 15 decides the allowance value of every input port at each W cell time and the part 12 generates the backward pressure signal for every input port based on the allowance value that is decided at the part 15.</p> |
