In this paper we address the issue of faster connection establishment in a large vertically stacked optical Banyan (VSOB) network. The best known global routing algorithm, which turns an N×N crosstalk-free VSOB network into a rearrangeably nonblocking one, has time complexity O(NlogN). This is quite large compared to O(logN) time complexity of a single plane banyan network, which is a self-routing network with very high blocking probability. For a large size of switching network this O(NlogN) time complexity may result unacceptably long delay. Therefore, an optical network with very low blocking probability and O(logN) time complexity will be useful. Previously proposed Plane Fixed Routing (PFR) algorithm has O(logN) time complexity but results in higher than 2% blocking probability with zero-crosstalk constraint for a network as large as 4096×4096 at full load. In this paper, first we propose the pruning of VSOB networks that reduces the hardware cost by almost 30%. The networks can still use the PFR algorithm and results in the same blocking probability. However, we show that the blocking probability can be reduced dramatically while keeping the optimum time complexity O(logN) by allowing only a small amount of crosstalk. Then, we propose a new kind of switching networks in which extra regular banyan planes have been added with the pruned VBOS (P-VSOB) networks. Necessary routing algorithms, namely, PFR_RS and PFR_LS show that this new 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 for P-VSOB networks. Both these algorithms also have time complexity O(logN).