Wednesday, February 09, 2005

Wavelength Services for Bandwidth Ala Carte

When we think of fiber optic carrier services, it's generally in terms of lines and channels. Wavelength division multiplexing has now added the option of leasing a lambda. A lambda is one of many individual wavelengths or "colors" being beamed down a fiber optic cable. It's like having a whole fiber optic circuit to yourself, but for a LOT less investment than trenching your own fiber network.

WDM or wavelength division multiplexing turns a single laser beam in a fiber optic cable into many beams sharing the same cable. The beams don't interfere because they are at different wavelengths, like colors of the spectrum. Each wavelength corresponds to a different carrier frequency in wireless lingo.

There are two flavors of WDM. CWDM or coarse wavelength division multiplexing is less demanding technically and provides 16 or so lambdas per cable. DWDM or dense wavelength division multiplexing is more technically challenging and spaces the individual wavelengths closer together. This gives typically 64 different lambdas and up to 80 or 100 lambdas, depending on the optical multiplexing equipment available.

Now, here's what makes WDM exciting. Fiber optic carrier services like OC3, OC12, OC48 and OC192 are based on SONET Synchronous Optical NETwork standards. SONET provides channels within a TDM based transmission scheme. Whatever you want to transmit first has to be formatted and loaded into available SONET channels, usually in ATM cells. At the other end, your data is recovered and restored to its original format. There is cost and inefficiency built into this process, including latency and jitter. Plus, when the line capacity is reached, you're out of channels and out of luck.

Lambdas are different. Buy a lambda and you can send whatever you want down that wavelength regardless of what other customers are doing with their lambdas. Some wavelengths might be used for OC48 SONET. Others can directly transmit Gig-E Ethernet signals or ATM, Frame Relay, Fibre Channel, or ESCON. This is known as protocol independence. Use a different protocol running natively on each lambda, and you don't have to worry about how to make them work together. One lambda doesn't even know the others exist.

If you would like to explore managed wavelength services or traditional SONET fiber optic carrier service, our consultants will be happy to quote prices and availability for your locations. No cost or obligation for this service through

Click to check pricing and features or get support from a Telarus product specialist.

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