Networking Cabling Basics

I have worked in the IT fields for over 10 years and have seen some pretty crazy cable management. I am not one to say that I am the best at managing cables either, I have been known to string a 100 ft cable across the room to get the job done. When I walk into a clients wiring closet or server room, I typically see something like the image below “Bad Wires 1”. This wiring management is very hard to troubleshoot, at first glance you do not know what wires go where. You have wires with varying lengths and colors. We are going to go over a few basic wiring strategies that any IT Professional needs to know.

Bad Wires 1

  1. Measuring and Neat Cables
    Longer is not always better. When you have cables going to many different devices, those long cables can become tangled with each other. This results into a tangled mess and hard to untangle. Measuring your cables to the correct length is very important. Exact cut cables look better, provide better airflow, and reduces cable waste. One may not think that the extra two feet isn’t much, but in the grand scheme of things, that adds up. The old saying measure twice, cut once still applies today.
  2. Labeling
    Who needs labels, I know where that cable goes! Six months later I found myself tracing a cable back to the wiring closet. As you’ve seen above, cables can get messy and you can easily loose track of a cable you are trying to locate. Labeling the cable on each end makes each end easy identifiable. I suggest investing in one of those electronic label makers. It makes labels easy to read and came in a variety of sizes and colors. Also, if you are troubleshooting devices and unplug a bunch of cables, you can easily figure out where they go. A few suggestions for labeling systems: have the label mean something, if the device is a switch at the north end of the building, name it SWITCH_NORTH_1. You have to keep it consistent throughout the network though, don’t change the label scheme halfway through, you will confuse yourself and others. For ports on the wall, make sure your label the port on the wall the same name as the one on the patch panel. In some cases, the label on the patch panel as extra digits to identify the port number. For example, HR0099.1C05, this tell me that this is the patch panel near the HR area on port 99 on switch 1 module C port 05. Now if I need to trace this back to the switch, I don’t need to spend time fumbling through the cables finding the switch port.
  3. Terminations
    Don’t buy cheap, because they are cheap. Don’t try to rush terminating cables. Terminating cables is an art and if they are not done correctly, you will find yourself redoing them, or worse troubleshooting all the bad terminations. If you wiggle a connection and they come apart, do it again! Keep practicing until you can do it without looking at other cables. Buy good tools to work with, the tools you use make the job easier and tend to crimp better.
  4. Test it!
    You may think you made the perfect cable, until you test it. Don’t skip the test, a good cable test will check more than just continuity, they will check the quality of the cable. A good cable will pass with 100%, if it doesn’t trash it and redo it.
  5. Short Patches
    Server, switches, and routers are in close proximity to each other, they don’t need three feet of cable connecting them. A patch cable is meant to be short. I went into a data center and saw three firewalls connected to each other with a three foot cable. The extra cable was routed in the back, bundled together, then routed back to the front to connect to the other firewall. This was a mess because you have cables running from the front to the back and front again. If you are troubleshooting cables, it would be hard to clearly know where those actually went. Use your skills to create the perfect length for each patch cable, this will avoid that tangled mess.
  6. Color coding
    I think this is by far the most important step to cable management. If you look at the image above, you see a rainbow of colors. This is a no, no, when it comes to troubleshooting. Sometimes it is hard to see where that cable goes, sometimes it is clear. The rule of thumb is to stick with one color for your patching and your cable runs. If you want to get more specific about the colors, consider a color scheme for the type of network or device it will be connected to. For example, in the data centers I build all internal networks like iLo or management networks, all yellow, this let’s me know that this is the only thing this cable does. All cables that go to patch panels are blue, these are usually outside the data center that run to offices. Cables that run from patch panel to switch are black. Patch cables that interconnect are purple, this identifies them as interconnected cables only. Cables that run from my data center to other switches are purple, this allows me to see that these cables came from the central location instead of another switch or patch panel. If your severs have multiple ports that do different things, like Internet ports, internal networks, and management networks, consider different colors for those as well. Whatever you do, keep it consistent throughout, it will not only make things easier, and make your data center better-looking.
  7. Right size for the job
    This is not the case for conduit, don’t buy conduit for what you need now, but what you will need. You don’t know when you will add on, you just know you want to be prepared. It is cheaper to run bigger conduit now than it is to run another one later.
  8. Plan it carefully
    Design your data center in a way that it is cable friendly. Make sure to put racks in locations that makes it easy to get to and run new cables. Plan for expansion, run extra conduit, extra drops, not just what you need now. You would rather be prepared for what you will need than moving stuff around later to accommodate.
  9. Power and Data
    Running data and power together is never a good idea. Power lines leach signal noise and causes interference with data cables. Try to run power and data at least six feet apart. Try not to bundle a bunch of data cables together either, this can create the same affect as power does.
  10. Keep it cool
    You may think only the servers need to be cool — but that would be a poor assumption. Cable can get warm as well, and if you have a massive amount of cable, that extra temperature can lead to disaster. Design your data center in such a way as to keep your networking runs cooled, as well as the server racks.

Nesting prevention
Cabling is often an afterthought. But when you treat it as such, you are running the risk that you’ll find yourself elbow deep in a nest of networking cables, attempting to resolve issues that could have been prevented with just a bit of care up front.

Below are few images of good cable management.

Colorful Cables Back of patch panel Organized Labeled Network Cables

About bwilson 36 Articles
Mobile device specialist currently working as a system analyst, building out an IT infrastructure. I currently focus much of my work on relational databases as well as frameworks. The goal of my work is to continually improve processes and efficiencies.

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