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Fiber-to-the-Telecommunications Enclosure (FTTE)
FTTE is a standards-compliant structured cabling system architecture that extends the fiber backbone from the equipment room, through the telecom room, and directly to a telecommunications enclosure (TE) installed in a common space to serve a number of users in a work area. Its implementation is based on the TIA/EIA-569-B “Pathways and Spaces” standard, which defines the Telecommunications Enclosure (TE), and TIA/EIA-568-B.1 Addendum 5, which defines the cabling when a TE is used.
The FTTE architecture allows for any media choice from the TE to the work area; it may be balanced twisted pair copper, multimode optical fiber or single-mode optical fiber, or even wireless if an access point is installed in or near the TE.
The figure below shows a typical layout for an FTTE architecture. Core class Ethernet switches are used with a high data rate fiber backbone and server ports. Depending on the user’s needs, FTTE can be deployed in low-density or high-density configurations.
A low-density system might use one or two inexpensive 8-port Ethernet mini-switches as an example (these switches have eight 10/100 copper ports and one 1 Gbps fiber uplink). A high-density FTTE design might use commonly available 24- or 48-port switches (these switches are configured with one 1 Gbps uplink port per twelve 100BASE-TX user ports). This relatively high work area-to-backbone port ratio provides better performance than is typically provided to enterprise users. Both low and high-density FTTE architectures provide excellent performance in terms of bandwidth delivered to the work area.
The FTTE low-density design offers the highest performance to the work area because the 8-port mini-switch is totally non-blocking, i.e., excess “capacity” exists as 200 Mbps remains on the 1 Gbps fiber backbone to the TR when all eight ports are operating at 100 Mbps.
The switch is able to provide 100 Mb/s connectivity to all eight workstations simultaneously, because the aggregate total from the eight workstations is 800 Mbps and the uplink can provide 1,000 Mbps or 1 Gbps. The mini-switch in the FTTE low-density design is “non-blocking’ or “undersubscribed”. The high-density FTTE design represents a slight sacrifice in performance, but offers increased installation savings.
Compared to traditional hierarchical star architectures which use fiber in the backbone and UTP copper in the horizontal, FTTE architectures offer the potential for significant cost savings. When low-density FTTE architectures are deployed, the total savings for network electronics, fiber and copper cable and connectivity as well as labor and TR costs can result in a per port savings of more than 30% when compared to traditional hierarchical star architectures. A high-density FTTE system can save approximately 40%.
The TE is the heart of the FTTE architecture. It must provide sufficient capacity, as measured in EIA “rack units” (RU), to house the required active electronics and passive cable and connectivity products. Some telecom enclosures utilize a common frame design, supporting up to 14 RU, which may be used in ceiling or wall mount applications. With this design, the TE is installed in the ceiling with a flat cover over the frame to enclose the front of the enclosure and blend in with the ceiling tiles.
In a wall-mounted installation, the front cover is installed on the frame. Cooling fans are not always required in an office environment but there should be provision for them in the TE. In a wall-mounted application there is either a glass door that provides visual indication of the status of the electronics or a solid aluminum or steel door for applications like schools where additional security may be needed.
All in all, FTTE is an attractive structured cabling system option from both a cost and performance standpoint. The low-density designs offer higher performance than traditional HSA design and lower costs, while high-density FTTE designs offer excellent performance with potentially the highest level of savings. Since FTTE is a very flexible architecture that supports copper, fiber or wireless from the TE to the work area, we expect that it will appeal to network designers who want to bring the benefits of fiber closer to the user without running fiber all the way to the desktop.
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