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128 Chapter 6

5,000
Figure 6-1
Growth of the 4,000
metropolitan 3,000
optical switching
2,500
in $ millions 2,000
market

1,500
1,000
500
0
1998 1999 2000 2001 2002 2003 2004

Wide-Area Networks

In wide-area networks (WANs), DWDM is driving the emerging opti-
cal switching systems market. As more DWDM systems are
installed, managing many wavelengths becomes critical. Optical
switching systems enable the carriers to support optical layer
restoration while creating new optical layer services, such as optical
virtual private networks (O-VPNs) and dynamic “designer” wave-
length services.The carriers literally will be capable of designing the
service provisioning and bandwidth for the user. This designer effect
will create “ad hoc” service provisioning.
Opaque and transparent optical switches will have a role in the
long-distance network. Many of the major network suppliers endorse
the use of optical switching. These include Williams, Qwest, Extant,
and others. Opaque optical switches are more common in the market
(2000). However, transparent optical switching systems are nearing
the final stages of delivery from the following companies: Lucent,
Nortel/Xros, Chromisys, and Corvis.
Transparent systems are transparent to protocol and bit rate,
meaning that they are highly scalable and useful for disaster
recovery (backhoe fade, equipment failures, and so on) and network
reconfiguration tasks. This transparency in protocols enables the
carrier to literally move any type of data, such as Internet Protocol
(IP)-centric networks, ATM, and SONET.