Dense wavelength division multiplexing (DWDM) is a fiber-optic transmission
technique that employs light wavelengths to transmit data parallel-by-bit or
serial-by-character.
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DWDM works by combining and transmitting multiple signals simultaneously at
different wavelengths on the same fiber. In effect, one fiber is transformed
into multiple virtual fibers. So, if you were to multiplex eight OC -48 signals
into one fiber, you would increase the carrying capacity of that fiber from
2.5 Gb/s to 20 Gb/s. Currently, because of DWDM, single fibers have been
able to transmit data at speeds up to 400Gb/s.
A key advantage to DWDM is that it's protocol- and bit-rate-independent.
DWDM-based networks can transmit data in IP, ATM, SONET /SDH, and
Ethernet, and handle bit rates between 100 Mb/s and 2.5 Gb/s. Therefore,
DWDM-based networks can carry different types of traffic at different
speeds over an optical channel.