USDA, Forest Service relies on hybrid passive optical LAN

The use of passive optical LAN combined with structured cabling help maintain historical integrity and meet technology demands for the United States Department of Agriculture's Forest Service in Washington D.C.'s Sidney Yates Building.

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From the March, 2015 Issue of Cabling Installation & Maintenance Magazine

The use of passive optical LAN combined with structured cabling help maintain historical integrity and meet technology demands for the United States Department of Agriculture's Forest Service in Washington D.C.'s Sidney Yates Building.

By Sean Kelly, RCDD, TE Connectivity and Michael Wilson, RCDD, Tellabs

Every U.S. city has that one historical building that seems to stand out against all the rest. In Boston, we think of the 1742 Faneuil Hall where many public meetings were held during the American Revolution. In New York, the 1871 Grand Central Station is considered by many to be the city's most iconic historical landmark. Philadelphia's Independence Hall adorned with the Liberty Bell is yet another that comes to mind.

At the corner of 14th Street and Independence Avenue in Washington, D.C. there is one historic Romanesque building that sits in stark contrast against all others. Originally built in 1878-1880 as the Bureau of Engraving and Printing, and listed on the National Register of Historic Places for its unique architecture, the iconic Sidney Yates Building is now home to the USDA, Forest Service headquarters.

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Originally built from 1878 to 1880 as the Bureau of Engraving and Printing, and listed on the National Register of Historic Places for its unique architecture, the iconic Sidney Yates Building is now home to the USDA, Forest Service headquarters.

The Forest Service is the third-largest land manager in the U.S. with extensive visitors and several buildings in the Washington, D.C. area. How exactly does a land management agency headquarters undergo a complete renovation and deploy the latest technologies needed to sustain the health, diversity and productivity of the nation's forests and grasslands while maintaining the historical integrity of their headquarters location?

They look at each individual network technology and deploy what best suits the architecture, the bandwidth requirements, employee productivity and the overall mission of the agency. And sometimes there is a realization that no single technology will fit the bill, calling for a hybridized network cabling infrastructure that encompasses several of the latest technologies. In the case of the U.S. Forest Service's renovation of the Sidney Yates Building, that ultimately meant a balanced approach using multiple technologies that included a passive optical LAN, a traditional switch-based network, a WiFi network and a distributed antenna system (DAS)-not one of which can truly be considered the primary.

Thinking outside the box

Since the Forest Service first occupied the space in the 1970s, the Sidney Yates Building has undergone several renovations to maintain the facility's plumbing, mechanical, electrical and information-technology systems. With technology and the way people work evolving significantly over the past decade, the agency found itself with an outdated network and workspace that did not adequately support the current needs of its employees.

"The original space was designed to accommodate about 300 permanent employees with large 10x12 cubicles at a time when telecommuting and mobility weren't part of the way people worked," says Andrew Conseen Duff, technical lead and senior project manager for the USDA, Forest Service's facility move support team (FS-FMST). "We also had two other buildings in Rosslyn, Virginia, which required having to shuttle employees and visitors on a 15-minute bus ride between the two locations. With this renovation, we wanted to designate the space as the prime location for all Washington metro-area employees, reducing our rental costs by nearly $6 million a year. That meant we now needed to house 856 employees with capacity for 1200."

According to Duff, the average cubicle size shrunk significantly to just 6x3 feet, which is more than adequate for today's telecommuting work spaces and given the fact that all employees are never in the facility at the same time. The number of meeting spaces and conference rooms more than tripled to accommodate today's more collaborative work environment. "We also needed to triple the number of network connections and increase our bandwidth," says Duff. "This required quite a transition from the outdated Category 5 copper distributed switch network we had in place."

In considering the historical architecture, bandwidth requirements, employee productivity and the overall mission of the agency, Duff realized that no one approach would adequately support the needs. With employees and visitors demanding mobility for productivity and collaboration, the U.S. Forest Service needed to deploy pervasive WiFi via nearly 200 wireless access points (WAPs) as well as a distributed antenna system (DAS) able to support 3G, 4G and enhanced LTE cellular communications. The historical architecture of the building also made it impossible to maintain the industry-standard 90-meter distance limitation for all work-area outlets.

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The original space with large 10x12-foot cubicles was renovated with smaller cubicles to accommodate more mobile working conditions while maintaining the historical architecture-an environment that benefited from more than a single approach to LAN deployment.

"When we applied current TIA standards to the building, there were some limitations for a traditional switched copper network-we couldn't meet the distance rules for home runs, and there was no room for additional closets with power and cooling," says Duff. "We then had to test and evaluate technologies that could go beyond 90 meters. Our team was very interested in where a passive optical LAN could take us, but this would create an architecture that had not been deployed in the agency or USDA to date. The evaluation was a risk-based decision, which leadership, the CIO and architecture-and-engineering groups in the agency approved."

Sometimes referred to as optical LAN or OLAN, a passive optical LAN is a point-to-multipoint architecture that employs unpowered optical splitters to enable a single strand of singlemode fiber to serve multiple users (or devices). Passive optical LANs leverage the distance and bandwidth capabilities of singlemode fiber to deliver network access up to 20 kilometers (12.5 miles), eliminating any issues with traditional distance limitations.

A passive optical LAN comprises an optical line terminal (OLT) in the data center or main equipment room, optical network terminals (ONTs) at the end-user or device locations, and a passive cabling infrastructure of singlemode fibers that use splitter technology to "split" the single input path into multiple output paths. At the work area, an ONT terminates the singlemode fiber and converts the signal to one or more twisted-pair copper outputs to interface with Internet Protocol (IP) enabled devices, including Voice over IP (VoIP) phones, computers, card readers, cameras, video displays or WAPs.

Once perceived as a niche application, passive optical LANs are now gaining traction in a variety of government and enterprise office environments. According to Duff, the leading edge passive optical LAN technology was slightly beyond the comfort level of the agency, which was one of the main reasons for ultimately choosing a hybrid network: "Due to some skepticism and the need for buy-in from all stakeholders, it was too much to deploy only passive optical LAN in the building. That's why we hybridized the infrastructure to include both traditional copper and passive optical LAN where they best fit."

Despite some uncertainty among those unfamiliar with the technology, the benefits of passive optical LAN made it the ideal technology for installing a network among historical architecture and for creating flexible work areas for the high-churn, constantly evolving U.S. Forest Service.

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Historical features of the Sidney Yates Building like the original iron and granite staircase needed to be preserved, and the passive optical LAN approach allowed for strategically locating fiber distribution terminals without disrupting the architecture.

"The Sidney Yates Building is not an easy building from a network cabling standpoint, and we're thankful that the U.S. Forest Service was able to think outside the box and implement a passive optical LAN in an environment that might not typically deploy the most cutting-edge technology," says Greg Bramham, chief executive officer at Global Com Inc., the company responsible for the implementation of both the copper and passive optical LAN infrastructure, as well as project management for the entire voice, data, wireless and audio-visual network as a subcontractor of L-3 Communications, the prime contractor for the renovation. "The hybrid approach was really the best way to deal with the historical challenges, especially given the highly compressed project schedule. It also appeased those with a traditional mindset to whom passive optical LAN was completely foreign."

Duff stated, "I looked for a comprehensive technical team to integrate the innovative architecture into Yates and I found that with the team from Global Com, Inc. Their design group worked hand-in-hand with GSA, the architect, mechanical team and the integration team to make the vision come to life."

Calling on versatility and strategy

For the passive optical LAN, the U.S. Forest Service selected TE Connectivity's Optical LAN Solution (OLS) and Tellabs Optical LAN equipment. The OLS consisted of TE's 288-port and 432-port Rapid Fiber Distribution Hubs (iFDH), which administer fiber cable from the Tellabs OLT, a feature-rich, packet-based and high-bandwidth platform that supports incoming voice and broadband services. The iFDH uses splitters to distribute the fiber out to approximately 45 Rapid Fiber Distribution Terminals (FDTs) and mini-Rapid Distribution Terminals (mini-RDTs) that serve as compact consolidation points, and from there, to the Tellabs ONTs at the workstation.

For the OLT located in the main data center, the USFS selected Tellabs 1150 high-density OLAN chassis, which serves 1792 ONTs or 7168 Ethernet ports. Primarily the Tellabs 709GP desktop and 120W in-wall ONTs were deployed at the user level. From the OLT, singlemode fiber preterminated to SC angled physical contact (APC) connectors plug into cassettes housed in TE's TrueNet Fiber Panel (TFP) that serves as the interconnection point. The back of each TFP cassette features a 12-fiber MPO adapter for simple plug-in of the preterminated 12-fiber RapidReel feeder cables from the two iFDHs. Within each iFDH, the RapidReel feeder cable is stored on a reel and only the distance needed to connect back to the TFP is reeled off while the remaining slack cable is stored within the iFDH. As a result, there is no need to know exact cable lengths beforehand. The RapidReel can hold up to 152 meters (500 feet) of RapidReel feeder cable, allowing the iFDH to be located virtually anywhere in the building.

Mounted close to the work areas they serve, the FDTs also feature built-in Rapid Reels that hold either 12- or 24-fiber RapidReel feeder cables. These cables are pulled back to one of the iFDHs with the remaining stored at the FDT on the reel. Within each FDT, a localized patching field allows for single fiber cables to be distributed to work-area outlets for connecting to the more than 1000 Tellabs ONTs.

"We were able to strategically locate the hubs to support the entire facility. The 288-port hub supports users in two wings and the 432-port hub was more centrally located to support about twice the number of users in the remaining areas," says Todd Grabner, onsite project manager with Global Com. "The Rapid FDTs were also very versatile, and we were able to strategically locate them to deliver fiber to the ONTs without impacting the historical architecture, including main features like the original iron and granite staircase."

Within the Sidney Yates Building, the majority of the mini-RDTs were placed within the 3-inch raised floor that was deployed to maintain the historical architecture of the facility. In areas without a raised floor such as the promenade level, FDTs were strategically placed in casework for the ceiling fan coil heating system. Placement of the FDTs and mini-RDTs presented some challenges that required careful planning and coordination among Global Com crews.

"Due to the age of the building, the floor wasn't completely level so in some areas of the 3-inch raised floor, we didn't actually have the full 3 inches," explains Grabner. "We had to get creative with the basket tray and switch from 2-inch tray down to 1-inch where necessary. While the raised floor made for an easier installation, we did have to do some core drilling for pathways and find the best location for transitioning cables down to the raised floor."

At each work area, the Tellabs ONTs were mounted under the desktop. Some ONTs are powered locally, some are protected with a battery backup, and some use remote direct current (DC) powering. The ONTs support ITU-T G.984-compliant 2.5-Gbit/sec downstream and 1.25-Gbit/sec upstream transmission, and feature copper interfaces that support 10/100/1000Base-T Ethernet and Power over Ethernet Plus for connecting to a variety of devices, including laptops, personal computers, telephones, printers and other peripheral devices. The Tellabs ONTs feature dynamic bandwidth allocation that allows for modification of bandwidth distribution across the ports and increased quality of service. In some areas where copper was not feasible due to distance limitations, ONTs were also used for connecting to WAPs.

"Our users all have access to multiple Ethernet ports, which can be either the traditional copper network or the passive optical LAN, or a combination of both," says Duff. "For areas that couldn't be served by copper due to distance, the ports are all passive optical LAN, but the user doesn't know the difference-they only see a copper jack at the faceplate. A short copper patch cable runs from the ONT under the desk to the faceplate."

Because a passive optical LAN is passive, with no power required from the data center to the work area, Duff says that the U.S. Forest Service was able to reduce the footprint of the network cabling by two-thirds. The lightweight, smaller-diameter singlemode fiber used to connect the passive optical LAN components (i.e. OLT to ONT) also uses fewer cabling materials and requires less pathway space and fewer associated pathways materials, which in addition to being ideal for historical construction like the Sidney Yates Building also make for a more environmentally friendly deployment.

Covering all the bases

In addition to supporting some WAPs for WiFi and end-user devices throughout the building, the passive optical LAN was also used to support the latest AV technologies that allow the U.S. Forest Service to stream live video from remote devices around the nation to large wall-mounted touchscreen Mondopads located in conference rooms and training rooms. The multi-touch high-definition 55- and 70-inch Mondopads from InFocus are essentially giant tablets that serve as a digital interactive whiteboard and videoconferencing platform with full Windows capability.

"Even the Mondopads were supported by the passive optical LAN in some historic conference room areas and in the Fire Watch room, but we did have to get creative because we wanted these spaces to remain clean looking," says Grabner. "Because we didn't want the power feed for the ONTs to be visible on the wall, we ended up placing a DC rectifier in the closet and ran stranded wire alongside the fiber to deliver DC power to the ONTs."

The Category 6 copper infrastructure deployed alongside the passive optical LAN, except in areas that were beyond the TIA 90-meter distance limitation, also comprised cable and connectivity from TE. While Grabner believes that deploying only passive optical LAN would have exceeded the technology requirements and eliminated the need for the raised floor, he does see the hybrid approach as providing some key benefits.

"With the raised floor in place, the U.S. Forest Service has more space to add technology for future needs. While the copper network satisfied those that wanted to maintain a standards-based switched network, the hybrid approach certainly means that all bases are covered," he says.

The hybrid approach with copper, passive optical LAN, WiFi and DAS ultimately required an extensive collaboration among contractors and vendors that resulted in a state-of-the-art example of a diverse, resilient infrastructure. According to Duff, several manufacturers and federal agencies consider the model deployed at the Sidney Yates Building one that weaves design and technology into a useable space and one that the USDA now considers a model for all large building designs in the future. In fact, Duff has already started on his next building project, bringing the best forward from Yates to the new project.

"I may have been the lead on this project, but it was TE Connectivity, Tellabs and Global Com who really made it a success," says Duff. "All the contractors and manufacturers worked together and collaborated 100 percent on the architecture. As a result, we have true diversity in our infrastructure. Anything that runs on the traditional switched network can run on the passive optical LAN and the two serve as backup to each other. We deployed singlemode fiber for the backbone of the switched infrastructure and located the passive optical LAN components in a way that would allow us to migrate to all fiber if we wanted to, and we also used diverse pathways for redundancy and resiliency."

Sean Kelly, RCDD is a system application engineer with TE Connectivity ( Michael Wilson, RCDD is a solutions engineering manager with Tellabs (

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