Blocking behavior analysis of extended pruned vertically stacked optical banyan networks with link failures

To guarantee a high switching speed, routing in vertically stacked optical banyan (VSOB) networks needs special attention so that connections are established as fast as possible. Previously proposed Pruned Vertically Stacked Optical banyan (P-VSOB) networks used Plane Fixed Routing (PFR) algorithm, and has O(log₂N) time complexity. Blocking probability has also been analyzed for these kinds of networks having link failures. This paper deals with the blocking behavior of EP-VSOB (Extended Pruned VSOB) networks having link failures. In EP-VSOB networks a few regular banyan planes are added with the P-VSOB networks. Necessary routing algorithms, namely, PFR_LS and PFR_RS show that this switching network can reduce the blocking probability to very low value even with zero-crosstalk constraint while keeping the hardware cost almost the same as that of PVSOB networks. Both these algorithm also have the time complexity O(log₂N). The blocking behavior of EP-VSOB networks is much better than P-VSOB networks. Simulation results show that the blocking probability of the VSOB networks does not always increase with the increase of link-failures; blocking probability decreases for certain range of link-failures, and then increases again.