Page 291 - Optical Communications Essentials

Source: Optical Communications Essentials

Chapter
17

Optical Networks

Optical fiber communication technology has been deployed widely all over the
world and has become an integral part of telecommunications. This is due to the
fact that, compared to copper cables, optical fibers offer a much higher capacity,
are smaller, weigh less, and are immune to electromagnetic interference effects.
Initially the term optical networks referred to collections of optical cable routes
that were used for high-capacity point-to-point transmission links. In these net-
works much of the telecommunication network infrastructure still relied on using
electronic signals, particularly in critical functions such as routing and switch-
ing of signals. Currently the next generation of optical networks is transitioning
some of the routing, switching, and network intelligence into the optical domain.
This chapter first presents some general network concepts in Sec. 17.1, to show
what networks consist of and what the related terminology is. Section 17.2 then
describes the characteristics and implementations of SONET/SDH networks,
which are used for transmission and multiplexing of high-speed signals within
the global telecommunications infrastructure. Following this, Sec. 17.3 gives an
overview of the meaning and applications of optical Ethernet. A variety of fiber
applications to the so-called access networks are the topic of Sec. 17.4. These
networks represent the cable segments running from the service provider facility
to the business or home user. Finally Sec. 17.5 describes the evolution of optical
networks to include concepts such as using all-optical methodologies to reduce
the electronic overhead in packet transmissions and the idea of delivering optical
services directly to the customer.

17.1. General Network Concepts
To understand the concepts of optical networks better, this section illustrates
different types of networks, notes who owns and operates them, defines some
network terminology, and describes what the terms physical layer and optical
layer mean.
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