Passive optical lan blog


posted Nov 2, 2011, 5:35 AM by David Khorram   [ updated Jun 23, 2017, 3:22 PM by Virtual Augmented Reality ]


Developed for the consumer market, gigabit passive optical networks (GPON) are attracting growing military and enterprise interest as a local area network technology that offers increased bandwidth as well as dramatic reductions in capital, power and other costs.

Passive optical networks are a point-to-multipoint access mechanism that uses unpowered splitters to enable one fiber to serve multiple users. GPON is a standard that provides greater bandwidth by using larger, variablelength packets.

With military users in need of network solutions as efficient as enterprise or commercial markets, some companies, particularly Tellabs, are showing how GPON offers benefits on multiple levels.

For one, GPON helps deliver what has been referred to as a “70-80-90” set of benefits. Compared with LAN technology that entails stacked switches and copper, optical LANs that use GPON technology reduce capital expenses up to 70 percent when compared with legacy networks. It also reduces power consumption by up to 80 percent, and cuts floor and rack space by up to 90 percent, advocates say.

“GPON optical LANs also improve security and reliability, cut outside-plant fiber requirements in half, and virtually eliminate electromagnetic interference,” explained Charles Stone, director of government sales for Tellabs. “These benefits come with increased bandwidth, converged voice, video and data services, and a fundamental shift to genuine green building technology.”

Due to the advantages of fiber and passive architecture, GPON also provides specific benefits to both military and civilian government markets. For example, it complements alarmed solutions to the desktop. In addition, secure LANs with alarmed fiber provide an efficient and flexible SIPRNet solution that can change classifications from the switch to the desktop in minutes without service disruption or re-certification requirements.

“This is the only technology that can approach this level of efficiency, along with the low cost of implementation and maintenance,” Stone expounded.

Ease of Operation

GPON is particularly easy to operate and maintain, especially for the servicemembers who rotate in and out of duty stations. “This ease of operation results in a reduction in training requirements, simplified operations, and a reduction on the reliance of contractor outsourcing,” Stone pointed out.

He explained that these cost savings result, in part, from the highport density of GPON technology, with one 9-RU chassis being able to aggregate up to 8,196 Gigabit Ethernet ports. “Compared with yesterday’s LANs, a GPON LAN requires far fewer active electronics, thereby lowering total network element costs to meet the same requirements,” he said.

The passive infrastructure reduces costs in two ways. First, it replaces active workgroup switches with inexpensive passive splitters, and second, fiber’s light weight, superior tensile strength and flexibility reduce cabling installation labor hours.

According to Stone, operating savings begin with significantly lower annual maintenance support plans from the manufacturer, owing to the higher reliability of the carrier class network elements, and additional savings from the reduction in network elements required to provide the same or superior services than yesterday’s stacked-switch technology.

“GPON technology further decreases the total cost of ownership through a significant reduction in power use, extended refresh cycles due to the carrier-class nature of GPON technology, and a passive fiber infrastructure that does not require the upgrades that legacy LANs require, such as telco room switch and copper cable replacements,” he said.

There is also the elimination of emanation through copper. “With fiber instead of copper, the base/campus can keep up with increasing bandwidth demands at a lower cost, especially with the fact that copper prices have risen over 150 percent just in the last three years,” he added.

In addition, fiber does not radiate signals nor is it subject to electromagnetic interference like copper is, offering vastly superior security of the transmission medium.

On top of that, GPON provides power savings to meet government mandates. “GPON power reductions are up to 90 percent compared with legacy LANs,” Stone said. “This can materially affect mission accomplishment for locations that exceed commercial power availability.”

GPON alone can dramatically assist the government in achieving its 30 percent reduction in energy targets by 2015. This power savings has also helped agencies achieve LEED gold accreditations.

Fiber LANs dramatically reduce weight and space, two precious commodities aboard any ship or submarine. By eliminating the need for telco rooms, GPON LANs can operate in higher and lower temperature extremes than legacy LANs, since stacked-switches need to be cooled, while passive splitters do not. That is often a factor in tactical environments.

GPON also can extend the physical distance to the user. “GPON signals travel up to 30 kilometers from the switch to the user, whereas legacy copper Ethernet signals max out at 100 meters,” Stone explained. This range facilitates use for tactical LANs, training ranges, security cameras, and any other IP device the military uses.

GPON increases physical infrastructure durability and reliability while also reducing cost. That’s because optical fiber is now stronger, more flexible and cheaper per foot than copper cabling, an important attribute in both the field and in garrison.

“In addition to the physical benefits of fiber versus copper, fiber provides much greater bandwidth, enables more users per strand, and also costs up to 60 percent less than copper on a network basis,” Stone said.

Moreover, GPON consolidates voice, video and data traffic. Specifically, GPON also supports the ability to transport “plain old telephone service” interfaces over this same medium. This enables military users who desire the reliability of POTS to eliminate the need to maintain individual copper runs across bases.

“POTS users can communicate to either VoIP soft switches or to traditional TDM switches if a migration to VoIP has not yet taken place,” he explained. “GPON, of course, also supports native VoIP transport between VoIP handsets and soft switches.”

Tetsuro Murase, senior director of the business planning office of the business planning and development unit of Fujitsu, pointed out that one strand of GPON fiber optic can carry data from 64 to 128 subscribers within close proximity of the subscribers. From that point, the fiber branches out and information is transmitted to the respective subscriber.

“The benefits in this are that the costs are greatly reduced, as opposed to point-to-point transmission through telephone lines,” Murase said. “When compared to Gigabit Ethernet Passive Optical Network, which is standardized by the Institute of Electrical and Electronics Engineers, data can be transmitted through the Ethernet, POTS, and DS1 and DS3 lines, to name a few, due to a synchronized clock.”

Military Deployment

Enterprise GPON solutions are currently deployed within the Army, Air Force and Marine Corps.

“The Army is using GPON technology primarily for data networking, the Air Force is using GPON for data networking (NIPRNet and SIPRNet) and VoIP, and the Marine Corps is using GPON for VoIP, with plans to also use GPON for analog to ASSIP conversion, allowing them to connect inexpensive analog phones directly to VoIP soft switches,” Stone revealed. “Additionally, GPON is used by the intelligence community for data, video, and voice services.”

Stone described a recent business analysis performed for the Department of Defense to evaluate an Active Ethernet refresh compared to a Tellabs GPON application, which yielded compelling results in favor of a fiber and GPON deployment. “The customer was in a dilemma of having to replace all of its copper cabling for 650 SIPRNet users and an additional 210 unclassified users,” he said.

When taking into account the cost of new copper Category-6 cabling and associated build out and labor, new Active Ethernet electronics in the five closets required to support the installation, and continued operations and maintenance, the customer found that it could accomplish its mission with the same or higher level of system reliability and achieve significant capital and operating savings.

As a result, Stone argues that GPON technology is not merely a superior technology. “It is a disruptive technology and therefore requires a paradigm shift in how we think about access and distribution networking,” he said.

“GPON flattens out access and streamlines distribution, thus network design becomes primarily an arithmetic exercise as compared to a complex engineering effort,” he continued. “Network troubleshooting and restoration is done centrally by a smaller workforce; in fact, no repair takes place at the user site other than optical network terminal replacement of a 99.999 percent reliable device.”

That’s because users receive high definition video, voice and data services at guaranteed committed information rates. Existing telco rooms become broom closets and new buildings eliminate them altogether, using the real estate for far more productive activities. In existing buildings, massive HVAC systems sit idle, lowering energy bills and the maintenance costs associated with them. In new buildings, or in tactical environments, HVAC systems are eliminated from all nodes except the core.

“Incredibly, SIPRNet becomes convenient—an unthinkable paradigm in yesterday’s stacked-switch network,” Stone added.

Fujitsu’s Murase noted, however, that security may be an issue for GPON among military users, adding that quality of service functionality would need to be incorporated as well.

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