Energy saving improvements in IP networks through table lookup bypass in router line cards

The present paper deals with the energy efficiency of an IP network and proposes a novel energy-aware strategy overcoming the simple switch-off of network elements. The proposed approach is called table lookup bypass (TLB) and consists in bypassing the table lookup operation performed by IP routers´ line cards to forward packets. The basic idea is to freeze the forwarding engine of some line cards by forwarding incoming packets towards a single pre-determined outgoing interface. In this way a line card can be switched to a new state with a reduced energy consumption because its most power hungry functionality is disabled. The paper formalizes the energy consumption minimization problem when TLB capability is available in routers line cards in addition to the classical switch-off. Results demonstrate that the proposed strategy can significantly improve the network energy efficiency, especially when link switch-off is not possible or when the network is highly meshed, bringing additional saving up to 40 % upon the classical link switch-off.