Considerations for configuring twisted-pair cables

In this Q&A, author Jeffrey Beasley discusses what students who plan to take the CompTIA Network+ exam should know about twisted-pair cables, from configuration to troubleshooting.

CompTIA's Network+ certification ensures prospective network professionals understand the foundational knowledge to manage both wired and wireless enterprise networks.

Enterprise networks have entered a new era of digitization. Organizations are now increasingly focused on virtualizing their networks and moving toward cloud network environments, among a host of other new initiatives. The CompTIA Network+ certification exam covers these modern approaches to networking.

But, even with a heavy focus on these new concepts, introductory network principles are still essential for aspiring network pros to master. One of those essential topics is twisted-pair cabling, one of the oldest and most common tools in network infrastructure.

This importance is underscored in Networking Essentials: A CompTIA Network+ N10-008 Textbook, from Pearson. In Chapter 2, "Physical Layer Cabling: Twisted-Pair," authors Jeffrey Beasley and Piyasat Nilkaew dedicate an entire chapter to twisted-pair cables. In it, they provide an overview of twisted-pair cables, such as the different types of twisted-pair cables, structured cabling and cable standards, as well as how to configure, troubleshoot and terminate connections.

The Network+ certification exam tests applicants on their knowledge of twisted-pair cables, and the heavy focus on this topic accentuates the continued importance of twisted-pair cables in modern enterprise networking.

Here, Networking Essentials co-author Beasley explains why twisted-pair cables have endured in modern networks, explains how to configure them for an enterprise network and offers advice for candidates preparing for the CompTIA Network+ exam.

Editor's note: The following interview was edited for length and clarity.

Book cover of Networking Essentials: A CompTIA Network+ N10-008 Textbook, 6th Edition by Jeffrey Beasley and Piyasat NilkaewClick here to learn more
about the book.

Why are twisted-pair cables still so commonly used today?

Jeffrey Beasley: It's affordable. That's probably the biggest reason. It's affordable, and it's convenient. Also, there's a lot of legacy cabling already installed everywhere. Why get rid of it if it works? If you're meeting your objectives with your data rates and data transfers, it's not a problem.

The world is switching to everything being wireless, and that's a big change. But there's a lot of convenience in twisted pair. In large enterprise-type applications, where you have thousands of computers connecting to your network, having a wired connection is very convenient.

You mentioned how the world is switching over to wireless. For network professionals who typically work in wireless environments, is twisted-pair cabling still important to understand?

Beasley: If you're going to go into the world of networking, you've got to know all facets of it. Wireless is a part, but the wired systems are just as equally important. If you're going into this world, you should have an opinion of whether Cat5 and Cat5e can still be used. You need to know the limitations because there's going to be a lot of that around. You need to know whether or not Cat7 or Cat8 is appropriate. You need to know all those aspects.

How do cable standards ensure that twisted-pair cables can handle modern networks?

Beasley: Those cables are tested and certified to be able to handle data rates [and also include] the limitations in terms of data rates. A key one is the distance limitation. [Cables] typically [support] 100 meters, but you've also got to make sure you allow for the cabling in the closet and in the work area to meet all those requirements.

How do network professionals configure enterprise networks with twisted-pair cables?

Beasley: You have your campus backbone cabling, and if you're going to be carrying any amount of data, you've got to have a place for your data. That's going to your communication service provider. Then, you have your building wiring associated with that. You have to set up your cabling and make decisions on that.

You're going to wire things up so that [devices] have instant access. To do these things, I'm going to want to use a twisted cable for my staff because it gives them instant access and they don't have to worry about getting a wireless connection. If they're carrying a notebook or laptop, then they're typically going to connect with wireless. When taking care of your office pool and work area, you're going to want to make sure you have cabling to all those settings in a fixed area.

Then, it's going to go to a closet area, so you have to make sure you allow for that. Beyond the closet, you're going to start getting into more of a backbone. Let's say that you have a four-story building. Each floor is separate, but they all join together. So, now, you have four floors of your building attached to [your network]. Now, you have a lot of data all being brought together.

You as the person who's concerned about things needs to look and say, 'Is twisted pair sufficient for handling that?'

It was OK for taking care of people in the work area, but now, I have 100 people from that work area who are running a lot of data and taking up bandwidth. You're joining them all together, so you need a bigger pipe to be able to get your data transferred in a reasonable amount of time. If I want to make sure my network still has good performance, I need to make sure I have a lot of bandwidth. At that point, you're going to go fiber. It's only reasonable.

Once the network becomes more complex with multiple connections, do you think enterprises should switch over to fiber cables?

Beasley: If you have a lot of data and you need very high speed, you can do that with twisted pair, but twisted pair is distance-limited. Even if it's running a whole lot, it can only go so far. If you're setting up your network system, then it's going to be a mixture of twisted-pair and fiber cables.

What are some important things candidates should understand about twisted-pair cables?

Beasley: One thing I always said when talking to my students is: 'You have to learn how to talk to us -- to engineers.' And know those key terms listed at the beginning [of the chapter]. The CompTIA Network+ exam has its own key terms. When we wrote the book, we wrote down what we thought was most important about the terms.

Anybody coming into this field has to know how to talk to [network engineers]. More importantly, they have to understand what we're referring to. If I refer to EIA [Electronic Industries Alliance] or TIA [Telecommunications Industry Association] -- which talks about the standards -- or if I mention T568A and T56B, or full-duplex, they need to have a good understanding of those things because that's the way [network engineers] talk.

What do you think people find the most difficult to understand about twisted-pair cables?

Beasley: There's a learning curve just to get to where you can terminate a cable and do it properly. When it's tested, it will meet specifications. In other words, if you put in a cable and it's supposed to be able to handle a certain data rate and you do a poor job of terminating it, there's a good chance the performance is going to be bad. Terminating the cable is always a challenge for students to learn, but it's a quick learn.

Do you have anything else you'd like to add?

Beasley: I remember in talking with people that there'll be some tricky questions on the Network+ exam. Like I said, CompTIA has a list of key terms. If you address those issues, then you should be OK for the exam. It's very useful for people who are getting started in the business, and twisted pair is just one part of it. You've got a whole lot of other things you have to learn, but that's extremely important on the exam. And understand the benefits, and the cost benefits, of doing a wired system.

Jeffrey BeasleyJeffrey Beasley

About the author
Jeffrey Beasley is professor emeritus of the College of Engineering at New Mexico State University. He is the author of four textbooks, multiple journals and conference papers. His areas of expertise are in electronics, communications and computer networks.

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