Selection of a rate adaptation scheme for network hardware

Rate adaptation is a family of technologies driven by the expectation that large energy savings can be achieved in packet networks by dynamically adjusting the capacity of network components to the load that they are required to sustain. In this paper we focus on packet-timescale rate adaptation (PTRA) techniques, which apply to individual traffic processing chips in the circuit packs of network systems. We look at the available options for PTRA implementation and compare their performance in realistic multi-device configurations. We find that in linear multi-device topologies the sleep-state-exploitation (SSE) scheme, which only adds a sleep state to the ordinary full-capacity state, offers the best compromise between energy savings and the unavoidable packet delay degradation of PTRA.