Specifications

Wavelength Division Multiplexing
36 Continuous Access and Data Replication Manager SAN Extensions Reference Guide
A key advantage to WDM is that most architectures are protocol and bit-rate
independent. WDM-based networks can simultaneously transmit data in Fibre
Channel, Internet Protocol (IP), Asynchronous Transfer Mode (ATM),
Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH),
and Ethernet protocols, and can simultaneously handle multiple bit rates.
Topics in this chapter include:
■ Commercial applications‚ page 36
■ WDM product variations‚ page 37
■ System characteristics‚ page 38
■ Qualified vendor products for WDM‚ page 39
Commercial applications
From a Quality of Service (QoS) viewpoint, WDM-based networks create a
lower-cost way to respond quickly to customers’ bandwidth demands and protocol
changes. This is because each new wavelength is a new, full bandwidth
communications pipe. In many areas of the world it is much cheaper to deploy
WDM technology on existing fiber than it is to install new fiber.
After WDM has been implemented, service providers can establish a
grow-as-you-go infrastructure. WDM gives service providers the flexibility to
expand capacity in any portion of their networks—an advantage no other
technology can offer. Carriers can address specific problem areas that are
congested because of high capacity demands. This is especially helpful where
multiple rings intersect between two nodes, resulting in fiber exhaust. (Fiber
exhaust means that the traffic volume on the Internet and other networks has
exhausted collective bandwidth available through installed optical fiber lines.)
By partitioning and maintaining different dedicated wavelengths for different
customers, service providers, for example, can lease individual wavelengths—as
opposed to an entire fiber—to their high-use business customers.