WDM...it's not new folks.

One thing I do blame UTP for, is for the way it steered the industry towards a baseband mentality, that is one where a single service is delivered over a cable.

Now, a single service is fine when that is all that your cabling is capable of delivering. But, when you have a broadband cable infrastructure, why on earth are we treating like a baseband system??

WDM has been around for over 20 years, and is the secret behind our ability to push long haul transmissions and to re-use existing lit fibre cores to deliver multiple disparate services. It really only started to become commercialised enough to be used by Enterprise

CWDM enjoys a very wide channel spacing in its ITU plan, the knock on benefit deriving from the lower cost optics. Spectrum analysis of a typical CWDM SFP resembles a standard vendor 1000Base-XX or 10Gbase-X offering, evidenced by the same spectral width and OSNR values.

This means a channel plan that may be limited in capacity, and importantly insufficient to deliver higher speed channels, but it is still a great migration strategy, and can easily co-exist with a DWDM overlay with careful planning and channel selection.

The following table lists the ITU-T CWDM channel plan and its associated frequencies. Note the 20nm spacing, this is equivalent to a traditional gigabit or 10gb SFP, a marked difference to that of a DWDM.

Regardless of which WDM option is best suited, using the inherent broadband nature of our underlying fibre cable to deliver only one channel ?? That's like installing a TV antenna for each TV station on the roof of your home.

Hah! Who would be that silly......

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