Computer Communication Network Upgrade for Optimal Capacity Related Reliability

Capacity-related reliability (CRR) computes the probability that a computer communication network (CCN) has at least a bandwidth Wmin between a pair of nodes. The quality of service (QoS) metric extends the terminal-reliability and the network-flow measures to capture the effects of any required message bandwidth, channel capacity, and network connectivity in a CCN, where links (connection services) are subject to failures and each connection has different bandwidth. An optimal CRR is achieved during the network design phase, or by upgrading the existing network. Since network upgrade comes at a cost, upgrading inappropriate network components may waste resources, and therefore an optimal upgrade should maximize QoS improvement with minimum resources. This paper presents a brute force approach to find a bottleneck link whose upgrade achieves a maximal CRR improvement. To reduce its time complexity, we also propose an efficient heuristic that obtains the link with high probability. We have implemented the algorithms in C, and used them to find the bottleneck links on some typical CCN. The simulation results to show the effectiveness of the algorithms are presented in this paper.