  In this paper, we consider the bandwidth-delay-hop constrained routing
problem in large-scaled software defined networks. A number of demands, each of
which specifies a source vertex and a sink vertex, are required to route in a
given network. We are asked to select a subset of demands, and assign a routing
path for each selected demand without violating the hop and delay constraints,
while assuring that the bandwidth occupied in each edge is not beyond its
capacity. The goal is to maximize the throughput (the total bandwidth) of the
selected demands. We develop an efficient heuristic algorithm for the problem,
which consists of three main steps, namely, computing feasible paths for each
demand, sorting the demands with some priority rules, selecting a path for each
demand. The algorithm is tested with networks of actual sizes and topologies,
generated by Huawei Technologies Company. The experiments show that the
proposed approach outperforms existing algorithms both in throughput and in
running time. In the experiments, our algorithm achieves more than 90\% of the
total bandwidth of the given demands within 10 seconds. Moreover, a large part
of our algorithm can run in parallel which largely speeds up the process when
using multi-core processors.
