Chapter 2 - SONET/SDH Networks

Abstract

This chapter focuses on the Synchronous Digital Hierarchy (SDH)/ Synchronous Optical NETwork (SONET) technology. The chapter discusses the fault, performance, and configuration management aspects of the network recovery in the SONET/SDH transmission networks. The SDH/SONET technology is widely accepted as a network technology that has already proven to be capable of providing very fast protection switching. A transmission network can be decomposed in one or more layers. Each network layer can be modeled as a set of atomic functions interconnecting the reference points in the network layer. One of the major progresses in SDH is that the clocks used for processing the received signals and generating signals to be transmitted in all nodes are synchronized with each other through a synchronization network. This allows byte interleaved instead of bit-interleaved multiplexing and prevents stuffing to compensate for the frequency mismatch between the different clocks. Accessing each individual multiplexed signal is possible by using a pointer to the appropriate byte in a repetitive frame structure, thereby avoiding the need to demultiplex (and re-multiplex) the high bandwidth aggregate signal, significantly reducing the complexity of the network equipment.