Abstract: A Virtual Private Network (VPN) aims to emulate the services provided by a private network over the shared Internet. The endpoints of VPN are connected using abstractions such as Virtual Channels (VCs). Reliability of an end-to-end VPN connection depends on the reliability of the links and nodes. VPN service providers provide new services with Quality of Service (QoS), guarantees are also resilient to failures. Supporting QoS connections requires the existence of routing mechanisms that computes the QoS paths, where these paths satisfy the QoS constraints. Resilience to failures, on the other hand, is achieved by providing, each primary QoS path, a set of alternative QoS paths, upon a failure of either a link or a node. We aim at to minimize the total bandwidth reserved on the backup edges. The above objectives, coupled with the need to minimize the global use of network resources, imply that the cost of both the primary path and the restoration topology should be a major consideration of the routing process. It turns out that the widely used approach of disjoint primary, restoration paths is not an optimal strategy. Hence, the proposed approximation restoration algorithms construct a restoration topology and this topology protects a portion of the primary QoS path. This approach guarantees to find a restoration topology with optimal cost which satisfies the QoS constraints.
R. Ravi and S. Radhakrishnan , 2007. Enhanced Restoration Algorithm in Virtual Private Network with Qos Support . Asian Journal of Information Technology, 6: 1035-1040.