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CTO INDUSTRY INSIGHTS

Wavelength Mobility, Giving More than Just Bandwidth


Wavelength Mobility, Giving More than Just Bandwidth

As with most emerging technologies, it is not uncommon for the full bundle of benefits to be misunderstood, or overlooked in the beginning. Currently, we see the industry focusing on a Gigabit Society, and all emerging access technologies being viewed through the lens of how they will address the bandwidth needs of this society. While this capability is a table-stakes requirement, it is one of many benefits NG-PON2 can bring to a modern service provider’s network.

Modern PON networks frequently face challenges over and above that of pure bandwidth. With NG-PON2, thanks to its implementation of multiple wavelengths per physical PON network, operators are presented with new possibilities to improve service performance and availability. Capable of coexisting with existing PON signals, due to wavelength separation, NG-PON2 can usher in the next wave of multi-Gigabit access and backhaul applications, while the more modest superfast service offerings continue to be delivered via GPON on the same physical PON network.

With NG-PON2, multiple 10G symmetric PON wavelengths can be injected onto one physical PON network at the same time. The ONU on the end-user side of the PON can then be signaled to tune to the desired wavelength. Once an ONU has tuned to the desired wavelength, service delivery begins. Thanks to advancements in tunable laser technologies, the time it takes an ONU to tune to a wavelength or retune to another wavelength, it is now possible to establish service delivery in the range of 50ms. Such rapid tuning times, when, combined with centralized SDN control, create a foundation for new innovative approaches to be applied to the access network to improve efficiency, availability, and performance.

Simple examples include the detection of an OLT transceiver failure, which can have the centralized SDN controller instruct the impacted ONUs to tune to the wavelength of another transceiver on the same PON and remap all of the services through that transceiver, without the customers detecting an issue. Similarly, for scheduled maintenance, ONUs can be migrated to a maintenance wavelength, while activities like upgrades, or patching and splicing are performed on the OLTs of the active service wavelengths. Even examples where, during off-peak times, underutilized wavelengths can be extinguished, and their ONUs migrated to a single baseline wavelength for a specific PON, returning to their primary wavelength when traffic utilization justifies the powering up of the respective OLTs. This action alone can deliver millions of dollars in annual savings for power and cooling. The challenge of rogue ONU identification and isolation is greatly simplified through NG-PON2. If an ONU gets into a permanently on transmit state, blocking the ability of other ONUs on the same wavelength to transmit, the other ONUs can simply be migrated to another wavelength, leaving the rogue ONU in its broken state on a separate wavelength until such time that a field technician can replace it.

It is easy to view NG-PON2 as simply another path to more bandwidth. While it is that, it is also so much more.