Path hunt for efficient broadcast and multicast connections in

Abstract

To efficiently implement the algorithm for branching each broadcast call as close to the output of a multi-stage switching fabric as possible, the path hunt for a call path is performed by examining the actual contents of control memories that control the switching stages of the switching system, in order to determine whether--and if so, where--the desired call path may be branched from an existing call path inside of the switching system. For efficiency and speed, the examination is performed by monitoring control memory contents being read out for the purpose of controlling the switching stages, and contents of control memories of multiple stages are monitored in parallel using dedicated monitoring hardware. To avoid the need to examine the control memories' contents in order to determine how much of a call path can be torn down without breaking call path segments shared with other existing call paths, separate counts are kept of instances of present use of connections between stages of the switching fabric, which counts are incremented upon creation of any branching paths that use these connections and are decremented upon breaking of any branching paths that use these connections.