Strictly Nonblocking f-cast Photonic Switching Networks under General Crosstalk Constraints

We derive conditions under which a d-ary multilog network is f-cast strictly nonblocking under the general crosstalk constraint that no active route can share more than c switching elements with other active routes. The problem setting is very general and thus challenging in many ways: (1) f-cast covers both unicast (f = 1) and multicast/broadcast (f = N), (2) d-ary networks are much more general then the commonly considered binary multilog networks, and (3) the crosstalk constraint covers both the usual link-blocking case (c = n) and the crosstalk-free case (c = 0). Prior to our work, results with the general crosstalk constraint are known only in the unicast case. Other results on strictly nonblocking f-cast networks are known without the general crosstalk constraint. Most of these known results are corollaries of the results in this paper. Additionally, our analytical approach based on linear programming duality makes it very easy to verify sufficiency proofs.