DWDM: White Knight on IP Horse

Optical

networking refers to a set of technologies, which carry

information across the networks in the form of light pulses.

Optical networking provides the backbone to support existing and

emerging technologies with almost limitless amounts of bandwidth

capacity. All-optical networking (not just point-to-point

transport) enabled by optical cross-connects, optical

programmable add/drop multiplexers, and optical switches

provides a unified infrastructure capable of meeting the telecom

demands of today and tomorrow. One particular technology, Dense

Wavelength Division Multiplexing (DWDM) is tipped to create a

glut of bandwidth in the core of many IP networks, thus enabling

them to handle the delay sensitive voice and video traffic.

DWDM

is a technology that puts data from different sources together

on an optical fibre with each signal carried on its own separate

light wavelength. Using DWDM, up to 80 (and theoretically more)

separate wavelengths or channels of data can be multiplexed into

a light stream transmitted on a single optical fibre. In a

system with each channel carrying 2.5 Gbps (billion bits per

second), up to 200 billion bits can be delivered a second by the

optical fibre. DWDM is also sometimes called Wave Division

Multiplexing (WDM).

Since each channel is

demultiplexed at the end of the transmission back into the

original source, different data formats being transmitted at

different data rates can be transmitted together. Specifically,

Internet (IP) data, SONET data, and ATM data can all be

travelling at the same time within the optical fibre.

DWDM promises to solve the "fibre

exhaust" problem and is expected to be the central

technology in the all-optical networks of the future. DWDM

replaces Time-Division Multiplexing (TDM) as the most effective

optical transmission method.

Unlike TDM, where all services

share the available bandwidth on a single channel, DWDM provides

separate channels for each service by transmitting mutliple

signals at different wavelengths through the same fibre.

By beginning with DWDM, service

providers can establish a grow-as-you-go infrastructure, which

allows them to add current and next-generation TDM systems for

virtually endless capacity expansion. DWDM also gives service

providers the flexibility to expand capacity in any portion of

their networks–an advantage no other technology can offer.