Hierarchical path hunt in a broadband multirate circuit switching fabric

A circuit switching fabric that switches narrowband (DS0), wideband (N×DS0, N×VT), and broadband (STS-N) signals embedded in SONET streams is studied. Based on the Clos (1953) strictly nonblocking principle, the fabric is strictly nonblocking if all path hunts are performed at the basic-rate (DS0 in our case) level. On the other hand, a hierarchical path hunt can speed up the path hunt process for a high bit-rate call, though the fabric will then lose its nonblocking property. We study several hierarchical path hunt algorithms and investigate how the hierarchy impacts the blocking probability. We also study the performance impact resulting from doing broadcast/multicast in a multirate circuit switching fabric. Our results provide insights into how hierarchical path hunts should be designed in a broadband multirate circuit switching fabric