POLANs & Structured Cabling: Key Compliance Considerations

In my last blog, "Optimize Passive Optical LANs with Structured Cabling", we discussed how structured cabling can optimize passive optical LANs (POLANs)

A POLAN includes an optical line terminal (OLT), passive optical splitters and optical network terminals (ONTs) that connect via singlemode fiber.

When deploying POLANs over structured cabling, there are key factors to consider to maintain TIA standards compliance.

Factor #1: Centralized Architecture

TIA requirement: There must be at least one telecommunications room (TR) on the same floor of the work area outlets it serves.

To deploy a POLAN over structured cabling, splitters should be housed in a TR or enclosure- or wall-mount cabinet. This provides a centralized location for easier MACs, troubleshooting and maintenance, and better splitter protection.

Factor #2: Connections Points

TIA requirements: Each TR be cabled via backbone cabling to a main cross-connect in the main equipment room, and that each work area outlet be cabled via horizontal cabling to a horizontal cross-connect in the TR. Only one consolidation point can exist within the horizontal cabling system.

Adding cross-connect connection points to a POLAN involves simply incorporating fiber patch panels at the OLT and another at the splitter. Another fiber patch panel placed between the splitter and ONT serves as fiber distribution to the work areas. Reconfiguring patch cords at the panels allows individual OLT ports to be connected to any splitter; fiber from the splitter can be connected to any ONT.

Connection points also provide a point of administration where individual ports can be adequately labeled per TIA-606-A labeling standards to identify the start and end of each connection.

Within the singlemode fiber run coming from the splitter, there should be no more than one other connection point. This consolidation point can be placed out closer to the work areas to then allow for shorter runs of fiber to ONTs.

Factor #3: Work Area

TIA requirement: At least two telecommunications outlets per work area (faceplate), and placement of application-specific devices external to the wall outlet.

There are a few ways to do this:

A duplex singlemode fiber can run from the splitter to a faceplate to either support two separate ONTs or maintain a second connection for backup.

Run a composite fiber/copper cable with one fiber connection for the ONT and a copper connection for other applications, or to deliver remote power to the ONT.

Some ONTs fit into a wall box, eliminating the TIA requirement for keeping application devices external to the wall outlet; however, it’s still possible to maintain some level of compliance by running either a duplex fiber or a composite fiber/copper cable to the ONT.

And Don’t Forget These Considerations …

Because POLANs operate in higher optical wavelength ranges (above 1500) like those used to deliver video, the connectors that make the connection points between components should be angled physical contact (APC) connectors vs. ultra physical contact (UPC) connectors. For more information, check out this previous blog.

Modularity of components has always been the cornerstone of deploying structured cabling, and POLANs are no different. The ability to easily house splitters in standard racks alongside upstream fiber connections from the OLT and downstream fiber connections from the ONTs provides the familiar footprint, manageability and space savings of traditional rack-based network connections.

At the core of Belden’s POLAN solutions, the feature-rich FiberExpress UHD System includes modular splitter cassettes, splicing cassettes and pre-terminated cassettes that can be quickly and easily installed to support connectivity for fiber from OLTs to splitters and fiber from splitters to ONTs—in a single rack unit. To learn more, download our white paper, “How You Can Optimize Passive Optical LAN through Structured Cabling”.