Lasers, Cable, PON Among Contenders for 100 Gbps Enterprise Networks

In the ongoing battle for higher network performance, 100 gigabits per second (Gbps) is emerging as the next necessary upgrade within the enterprise LAN. Increasing local network speeds will ratchet up wide area network (WAN) speeds between buildings and within cities, with new solutions coming to support 5G deployments and the cable industry’s evolution to 10 Gbps delivery for residences and businesses.

The 14th annual “State of the Network” global study conducted by VIAVI Solutions found more than 90 percent of IT teams  plan to deploy 100 Gigabit Ethernet (GbE) during the next three years, while 80 percent are planning to deploy 400 GbE in the same timeframe. VIVAVI attributes the migration to higher speed from 10/40 Gbps to 100/400 Gbps due to more applications moving to cloud hosting. There’s also been a dramatic drop in costs for 100/400 Gbps equipment, providing an affordable onramp for future-proofing your network.

Contenders for affordable, off-the-shelf 100 Gbps service delivery include repackaging of laser technology developed for satellite broadband networks, the cable industry promoting new standards for fiber transmission at distances up to 80 kilometers, and Nokia promoting an evolution of passive optical networking (PON) technology.

Free Space Optical returns (Or Frickin’ laser beams!)

Free space optical (FSO) is marketing speak for laser communications. Instead of using fiber optic cable as a conduit for laser light, a point-to-point network connection is established using two lasers and receiver pairs with the laser operating directly in the air.

More powerful lasers and larger receivers are needed for FSO than the humble electronics of fiber connections since light isn’t following the benign, predictable medium of glass but travels through air and is affected by weather. Current FSO laser solutions manufactured by companies such as Collinear provide up to full duplex 10 Gbps speeds for unobstructed straight-line distances of up to a kilometer with clear air; rain and snow potentially affect/lower data rates and effective distances while fog makes a solid laser connection very problematic.

Denver-based BridgeComm says its work on off-the-shelf terrestrial fiber optics components for satellite and UAVs will pay off for earth-bound needs, delivering 100 Gbps speeds at far greater distances.

“With our current system, we expect terrestrial links of 40 km to be quite reliable,” said BridgeComm’s Senior Vice President of Business Development Michael Abad-Santos. “We have tested through UV treated glass and have experienced minor attenuation at short distances, thus making it feasible for dense urban environments. We have not experimented at longer distances.”

While commercial pricing is still to be determined, BridgeComm’s increased performance and presumably more affordable equipment comes from tapping into decades of fiber optic electronics work. “There have been several advancements to fiber optic technology due to investments made by the terrestrial fiber optics companies,” Abad-Santos said. “BridgeComm has been able to benefit from those investments and develop systems utilizing mainly commoditized COTS components. The control electronics and modems are significantly more capable, smaller, and lower power than the last few generations. That makes this much more practical to implement.”

Weather is also expected to be less of a factor than with previous FSO implementations. “Since the atmosphere has tremendous variability, it is difficult to make blanket statements,” Abad-Santos said. “However, since we use 1550 nm [wavelength light], the penetrations through moderate snow and light fog are significantly better than visible wavelengths.”

There is “significant demand” for 100 Gbps solutions for enterprise fixed wireless access backhaul, rural and remote connectivity, as well as “significant interest” in FSO for U.S. Department of Defense 5G backhaul and fronthaul applications, Abad-Santos said.

BridgeComm is focusing its 100 Gbps FSO terrestrial solution on enterprise customers needing very high throughput, as well as government customers. “We are currently working a few commercial deployments, which are under NDA,” said Abad-Santos. “A full product release schedule is still to be determined. Commercial pricing is still to be determined.”

CableLabs Generates New 100G/200G Fiber Standards

The cable industry is conducting a long-term migration to 10 Gbps speeds, pushing fiber deeper into their networks while removing power-hungry analog fiber optic and legacy coax RF equipment along the way to improve reliability. As 10 Gbps services become available to residential and business customers, the need to increase backbone network speeds followed.

“What we wanted to look at is if there might there be a different solution that could be both more cost effective and more scalable than just doing 10 gig DWDM,” said Matt Schmitt, Principal Architect at Cable Labs. “The hypothesis was ‘what if the existing fiber link used a single 100 gig or 200 gig coherent optics wavelength,’ you send that out to a switch or a router that sits out to the field. Then you run low-cost 10 Gig optics links off the back end to connect to these remote PHY devices.”

CableLabs has established two standards for interoperable point-to-point (P2P) coherent optics links, using a single wavelength of light instead of multiplexing multiple wavelengths. The Physical Layer 1.0 (PHYv1.0) specification defines operations at 100 Gbps (100G) on a single wavelength while the PHYv2.0 specification brings up the speed to 200 Gbps.

The PHYv1.0 and PHYv2.0 standards enable high-speed Ethernet connections to be made up to 40 kilometers with no optical amplifiers on the fiber, going to 80 kilometers with the use of an optical amplifier. Schmitt says CableLabs has been “very successful” in getting network equipment manufacturers to build interoperable PHYv1.0 products, including hosting interoperability tests and demonstrations of multiple devices from different companies. Products based on the PHYv2.0 specification are in the pipeline.

Schmitt said the organization looked at defining 400 Gbps, but it would require higher order modulation schemes and more stringent optical requirements that don’t necessarily fit the need to establish a high-speed Ethernet link between a cable head-end data center and an outdoor unit in the field where services will be distributed to customers at the last mile.

While devices suitable for enterprise WAN connectivity are available and interoperable, CableLabs is waiting for the final piece for the industry’s specific deployment needs to emerge.

“The missing link for cable is the outdoor box,” Schmitt stated. “One of those has to go outside into a weather hardened enclosure… Most cable operators, at least in North America, generally prefer a clamshell type of device with a hardened enclosure that you put this into, and there is not on the market today a clamshell switch or router that supports coherent optics modules. Without that, you really don’t have a deployable solution.”

To 100G PON and beyond!

The cable industry isn’t alone in wanting to get more speed out of existing fiber. Nokia is looking beyond the core network to delivering 100 Gbps to residential end users. In February, Nokia Bell Labs and Vodafone announced the successful trial of new Passive Optical Network (PON) technology that can deliver up to 100 Gbps on a single wavelength.

“The (Nokia Bell Labs) trial used 25 gigabaud components,” said Ed Harstead, Lead Technology Strategist at Nokia. “First, you use DSP equalization to stretch from 25G NRZ (encoding) to 50G NRZ, with the 50G ONUs (optical network units) on the network listen to 50G NRZ and then second use PAM4 (encoding) to get another factor of 2 to 100G, what the 100G ONUs listen to.

PON is substantially different than a point-to-point optical connection, using a single optical transceiver and a hub or single location and an optical splitter to distribute service from a single fiber to 32 or 64 locations. The method reduces the cost of delivering service on a per location basis while introducing more complexity in network design and optical losses during the splits.

The “special sauce” in the mix allows 50G PON equipment to find and use excess optical margin – available laser light – to pack in twice as many bits per wavelength of light, allowing 50G PON transceivers to operate at 100G. Harstead said 100G PON, when commercially available, should be able to be implemented on today’s gigabit PON and 10 Gig PON networks as a plug-and-play electronics insertion ,with 100G PON services running in parallel with legacy PON service on the same fiber plant simply by using a different wavelength.

Nokia’s February press release said 100G PON could be commercially available in the second half of the decade, but service providers and business customers may want to see it sooner given the interest in 100G for 5G deployments and today’s movement in the broadband industry from gigabit data rates to 10 Gig as the new top-line standard, not to mention CableLab plans to make 10 gig data rates the industry benchmark.



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