Scaleable bandwidth interconnect for simultaneous transfer of mixed pleisiochronous digital hierarchy (PDH) clients

The present invention relates to a scalable bandwidth interconnect bus that provides a multipoint-to-multipoint interconnection between communications devices supporting a large number of individual links for use as a high channel density interconnect with optional cross connect capability. The scalable bandwidth interconnect bus supports a synchronous mode of operation as well as an asynchronous mode of operation employing flexible timing mastership. A scaleable bandwidth interconnect (SBI) for interconnection of physical layer devices with link layer devices which includes an ADD BUS interface operative to receive data from one of the link layer devices and direct it to one of the physical layer devices and a DROP BUS interface operative to receive data from one of the physical layer devices and direct it to one of the link layer devices. By utilizing buses to access each of the physical layer devices and the link layer devices permits interfacing between a high density of physical layer devices and a high density of link layer devices.