In static networks essentially all functionality resides in the network access stations (NASs). The performance of the network is therefore determined by how the NASs provide logical connectivity and throughput to satisfy the network's traffic requirements. This chapter explores the performance issues in static networks, viewing them all as special cases of shared media, as described in Section 5.1. Existing and potential uses of shared media abound, the most important of these being to provide efficient local access for end users to a larger optical network. The multiplexing and multiple-access techniques required to achieve multipoint logical connectivity in these networks are treated in Section 5.2. Sections 5.3 through 5.6 deal with capacity allocation and control to serve prescribed traffic requirements. We first point out some general flow conservation constraints that must be satisfied in any shared-channel system. Then the problems of traffic scheduling and control are discussed in settings with increasing degrees of complexity: dedicated connections (Section 5.4), demand-assigned connections (Section 5.5), and packet switching in the optical layer (Section 5.6). Section 5.7 discusses network access applications of static multipoint architectures. These include broadcast star-based and wavelength-router-based passive optical networks (PONs) that provide the foundation of fiber to the home/premises. In these applications the static network is the link between the end user and an optical core or metropolitan area network.

Shared Media: The Broadcast Star

The simplest form of a transparent optical network, the static network, was defined in Chapter 3 as a collection of fixed (passive) splitting/combining nodes without wavelength selectivity, interconnected by fibers that provide full or partial connectivity among a set of NASs.