Architectural Considerations in the Design of WDM-Based Optical Access Networks

We describe a WDM-based optical access network architecture for providing broadband Internet services. The architecture uses a passive collection and distribution network and a configurable Feeder network. Unlike earlier papers that concentrate on the physical layer design of the network, we focus on higher layer architectural considerations. In particular we discuss the joint design of the electronic and optical layers including: WDM Medium Access Control protocols; the choice of electronic multiplexing and switching between the IP and WDM layers; joint optical and electronic protection mechanisms; network reconfiguration algorithms that alter the logical topology of the network in response to changes in traffic; and traffic grooming algorithms to minimize the cost of electronic multiplexing. Finally we also discuss the impact of the optical topology on higher layer protocols such as IP routing, TCP flow control and multi-layer switching.