Load Balancing Routing of Fault Tolerant QoS-Guaranteed VPNs

As both end-to-end network reliability and performance becomes a growing concern for large distributed organizations, carriers face an increasing pressure to offer enhanced network services with higher quality of service (QoS). Such premier services are exemplified by wide-area virtual private networks (VPN) with QoS guarantees, or QVPNs, for which users can specify bandwidth, latency, and reliability requirements. From a carrier's standpoint, the primary challenge is to set up fault-tolerant routes for each QVPN request across its network with user-specified reliability and performance guarantees and, at the same time, maximize the total number of QVPNs that its network can support at any instant. We propose a fault tolerant load balancing routing (FTLBR) algorithm to select fault-tolerant routes for QVPNs. FTLBR maintains network-wide load balance while selecting primary and backup routes for QVPNs and performs resource sharing along backup routes to achieve an overall high network resource utilization efficiency. FTLBR is able to avoid formation of bottleneck links during primary-backup route selection by employing a simple quantitative metric that effectively captures network-wide load balance. Simulation results show that FTLBR can support significantly higher number of QVPNs when compared with existing traffic engineering algorithms.