Cabling for LAN and Premise Architecture

July 31, 2013 at 10:00 AM

 

Diagram of Wiring Closet Rack

It's hard to fathom just how quickly Ethernet technology has grown. Today no modern office building would be functional without premise wiring, or the cabling run throughout the building to connect computers to the LAN.

 

We may be on the verge of a wireless revolution with new technologies like DAS and MESH, but for now you should at least understand the basic architecture of LAN cabling.

 

LAN wiring is often broken into three types: backbone, horizontal runs, and patch cabling, each with its own purpose and requirements. In an especially large building or in a campus of buildings, the backbone is the wiring that connects server locations together and to the Internet through an ISP. Since a large amount of data may be carried back and forth by these cables, they are typically designed for bandwidth, like T1 lines or fiber optic cables (usually multi-fiber lines like breakout or distribution style, or even ribbon fibers).

 

Close Up View of Solid Conductor Category-rated Cable

The horizontal runs are the individual cables coming from the servers to the Work Areas. Work Areas are the points where the cable is terminated in a wall plate or jack so a user can plug their computer or other device into it.

 

It is often deceptive to assume that a single horizontal run will connect to a single computer. More likely than not, it is connected into a local Ethernet switch or wireless access point, and many computers may be connected to that. For this reason, the actual data carried on a single horizontal cable could vary greatly, and if you are planning your LAN architecture, this is the trickiest thing to get right. It can also be the most expensive piece to change if you get it wrong as you may need to fish the cable back out of a wall or conduit to re-arrange it.

 

Horizontal runs are currently most often solid-conductor Category rated copper cable. This is slowly changing over to fiber optic cabling as the price gap between the two narrows and fiber optic technology improves. Note that the horizontal cable may also require special jacket types to comply with building fire codes.

 

Right Angle Ethernet Cable Assembly

The patch cabling in a LAN is often overlooked, but is also very important. In general it is used to connect two devices together in a rack in a server room, or to connect a device to a wall jack where a horizontal cable is terminated. Being exposed (not behind a wall or on a rack ladder) and possibly being moved frequently, a patch cable needs to be robust and flexible.

 

While patch cables are easily available and can be bought relatively cheap, you might want to consider that cheap cables may introduce problems to your LAN. Cheap cables often use substitute materials such as copper clad aluminum or feature low quality plugs not rated for the application. Cheap cables seldom pass the testing required for the network and will degrade your network performance.

 

With more devices requiring power (POE), the cheaper cables often cannot carry the added burden due to undersized conductors and low grade copper. For a single user's computer, the impact of this may be limited, but in a server room low quality cables can have a disastrous effect on the entire LAN. If the cable manufacturer you purchase from has a robust QC process, it will help.

 

Other features to consider are molded right angle connectors to ensure the connector isn't bent to fit into limited space, cable boots to make depressing the connector latch easier, and high-flex construction and oil resistant jackets for demanding environments.

 

L-com stocks components for every facet of your LAN, from Ethernet cables, plugs and jacks, to bulk copper or fiber cable, to active media converters. We also go beyond that, to reliable racks, panels and cable management accessories, lightning and surge protectors, Power-over-Ethernet components and everything for wireless deployment.

 

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