Energy Efficient Multi-Topology Routing Configurations for Fast Failure Reroute in IP Networks

IETF has defined IP fast reroute (IPFRR) schemes to enable IP networks with fast failover capability. Fundamentally, failure recovery is achieved by provisioning backup paths on standby network resources to provide traffic rerouting for bypassing a failed device. Unlike survivable network designs, the principle used in designing a green network is the opposite. To minimize energy consumption, traffic engineering techniques are applied to aggregate traffic flows on limited network resources. Thus, the unused network devices can be turned off or put on sleep mode to save power. How to reduce power consumption while maintaining high survivability is quite challenging. In this paper, we first evaluate the required number of active links for an IP network operating at its maximum survivability ratio. The results indicate that power saving is quite limited using standard IPFRR. We identify that this result comes from the inflexibility of IP routing using only one set of link metrics. To resolve this issue, we introduced RFC 4915 MTR into the design of a novel green IP network. The method we proposed uses only two routing configurations. Configuration 1 is used for routing traffic in the normal state and Configuration 2 is used to compensate Configuration 1 to enhance network survivability. We have formulated the problem as an integer linear programming problem and propose an optimization-based approach to obtain a solution. The numerical results indicate that the proposed method is not only energy efficient but also can provide 100% network survivability against any single link failure.