Green routing/switching and transport

In this chapter, we provide an overview of energy-aware routing solutions for backbone networks. After an introduction of energy-aware strategies for network scenarios, we investigate the fundamental power consumption features of IP routers. In this context, we classify energy-saving mechanisms in two categories: switch off and energy proportional. We focus our attention on switch-off solutions, providing the general formulation of the Integer Linear Programming (ILP) problem considering two different scenarios, that is, flow-based and destination-based. Due to the complexity of the problem, different heuristics have been provided in literature; we describe the main ones, highlighting the key features of well-known heuristics. Finally, we present an innovative energy-saving solution, referred to as Table Lookup Bypass (TLB), based on the deactivation of forwarding functionalities inside a router line card.