Freezing forwarding functionality to make the network greener

This work proposes a novel approach to reduce the power consumption of IP routers: freezing the forwarding engine of routers line-cards. In fact, recent studies showed that about 60% of the power consumption of a line-card is wasted to lookup the routing table during packet forwarding process. We first define the proposed approach, called Freezing Forwarding Functionality (F3). Then, we provide an ILP formulation of the energy minimization problem under F3mode and define a heuristic algorithm, referred to as Green Backbone Algorithm (GBA), to solve the problem in large networks. The performance of GBA is evaluated under different traffic scenarios in real ISP network topologies, and a comparison with the ILP solution is carried out for small networks. Results show that: (i) GBA performance, in terms of number of nodes in F3mode, are very close to optimal ILP solution ones; (ii) a large energy saving (up to 80% of nodes in F3mode) is obtained in large networks during low traffic hours; (iii) a limited impact on paths length increase is achieved.