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The key
inter-exchange market requirements include:
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·
Long distance transmission
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·
High aggregate capacity at one protocol (e.g., SDH)
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·
Monitoring and fault localization
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·
Fault tolerance (survivability)
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Low cost
As mentioned
earlier, long-haul telephone companies have been the most prominent
sector for WDM links so far.
The reason this
market is ripe for such a technology stems from the rapidly
shrinking pools of free capacity in existing fibers in the ground on
one hand, and from the above-mentioned very high costs of installing
long distance fiber on the other. In fact, these costs are so high
that they make the current WDM multiplexers seem reasonable.
Despite the
requirement for WDM point-to-point solutions, this market may not
need all-optical networks in the near future. The specific features
offered by such networks, such as configurability and transparency,
seem less attractive here, where single-hop OC-48/ STM-16 or STM-64
lightpaths are all that is necessary at this stage. In the long run,
if SDH networks are to be replaced by wavelength routing networks
(as may be the case for regional communication providers, see
discussion below), a similar need may evolve in this market as well.
So as the technology advances in optical networking, an evolutionary
technology-inter-exchange market mapping produces the following
roadmap for the transport network infrastructure evolution:
- SDH TDM
- SDH TDM with
SDM (space division multiplexing-multiple fibers)
- SDH TDM with
WDM links
- All-optical
networks (dynamic or static wavelength routing networks)
- OTDM or MC-OTDM
- OCDMA or MC-OCDMA
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