Policing control apparatus

Claim 1

A policing control apparatus comprising: a cell input terminal for receiving asynchronous transmission communication network cells; a policing circuit coupled to said input terminal for policing transmission of cells from said cell input terminal according to policing information; a cell output terminal provided as an output of said policing circuit for outputting cells policed in said policing circuit; a count memory in said policing circuit for storing a count value of the cells supplied to said policing circuit and for supplying said count value as said policing information; and a self-diagnosing circuit for monitoring problems in said count memory and abnormalities of stored contents in said count memory and outputting an alarm upon detection of a problem or abnormality; said self-diagnosing circuit including a first circuit for detecting a designated specific virtual path identifier (VPI), a timer for determining a policing cycle time for a service class identified by said designated specific VPI, a second circuit coupled to said first circuit for counting arriving cells identified by said designated specific VPI, and a third circuit coupled to an output of said second circuit for comparing contents of the count memory in said policing circuit and the output of said second circuit and for generating said alarm upon failure of identity of the output of the second circuit and the contents of the count memory.