Page 222 - Optical Switching And Networking Handbook

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High-Speed Applications 207

tinue to be an essential element of future interoffice fiber systems.
DWDM is a critical first step toward the establishment of photonic
networks in the access, interoffice, and interexchange segments of
the telecommunication infrastructure. Figure 8-17 is an example of
optical access links using the DWDM architecture in the metropoli-
tan area.
DWDM systems with open interfaces give operators the flexibility
to provide SONET/SDH, asynchronous/PDH, ATM, Frame Relay,
and other protocols over the same fiber. Open systems enable the
carriers to quickly adapt new technologies to the optical network
using “off-the-shelf,” relatively inexpensive, and readily available
transmitters.
Open interfaces provide operators with greater freedom to provi-
sion services and reduce long-term costs. Proprietary-based systems,
in which SONET/SDH equipment is integrated into the optical mul-
tiplexer-demultiplexer unit, are adequate for straight point-to-point

Figure 8-17
Optical access in
metropolitan
networks (Alcatel)

Repeaters

Source: Alcatel