Network Connectors – CompTIA A+ 220-901 – 2.1

We use many different connectors in our modern networks. In this video, you’ll learn about fiber connectors, twisted pair connectors and standards, and common coax network connectors.

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-There are three different kinds of fiber connectors that you’ll need to know for your A+ certification. The ST, the SC, and the LC.

The ST connector is the straight tip connector. It’s one that’s been around for quite some time. You can see the straight tip on the end of the fiber connectors. And they have this bayonet connection, which means that you push them into the connector, and you twist them to lock them in place. That way, it’s very difficult for that fiber connection to fall out, or to be accidentally pulled out of that fiber connection.

The SC connector is the subscriber connector. You might also hear it referred to as the standard connector. And some people call it the square connector because the end of it is this square. You also notice there’s no bayonet connector on the SCs, but they do lock into place when you push them into the connector. You pull on them slightly, and they unlock, and are then released from the connection.

LC stands for the Lucent connector. This might also be called the local connector and most commonly, the little connector because it’s much smaller than the ST or the LC connectors. And when you’re dealing with large amounts of interfaces on networks switches and other devices, it’s good to use the smallest connectors you can, so that you can fit more into that same component.

Here is the relative size of all of these connectors. You can see the connectors are here, with dust covers over the fiber connections. You got the ST connector on the right side, the SC connector on the left side, and the LC right in the middle.

Let’s shift gears to our copper connections. One of the more common copper connections, especially on modem connections is the RJ11 connector. This is a 6 position, 2 conductor connector. That Means there are six positions inside of this, but we’re really only using two of those. You can even see the two conductors inside of this RJ11 connector.

It’s very commonly used for telephone connections. In fact, there’s a variant of this that’s the RJ14, that still uses the six positions, it fits into exactly the same interface type, but there are four different conductors inside. You’ll very often see this used for dual-line configurations, so that you can use two phone line through the same cable.

For our ethernet connections, we’re using RJ45 connectors. This is an 8 position, 8 conductor cable. And you can see we’re using all eight of those copper connections inside of this. If you’re running a WAN connection, a T1, or some other type of WAN connectivity, it’s using a similar connection, but it’s really an RJ48C. It’s in 8 position, 4 conductor cable, but they look very similar to each other.

Whenever you’re installing fiber or copper cable into an environment, you want to be sure it’s done exactly the specification. You don’t want one end of the wire configured in one way, and the other end configured in another. And very often you want to test these wires prior to going into production. This is one where all the connectors look very similar, you can wire them in similar ways. So it’s good to have a mapping device like this that’s able to see exactly what the wiring is inside of those cables.

You might also consider getting a good cable person. Someone who is accustomed to installing this physical plant. Your network is all going to rely on how well this physical installation is. It’s very often a good thing to bring in an expert who’s doing this all the time.

One set of standards for twisted-pair cabling is the T568A and the T568B standards. These are standards from the Telecommunications Industry Association, and it’s really designed so that everybody’s using exactly the same wiring type. These pin assignments come from the EIA/TIA-568-B standard. And they’re are specific to 8 conductor ethernet cables there are 100 ohms in resistance.

You’ll find that the A and the B configurations are a bit different. You’ll see them listed as the T568A and the T568B. This is really designed for this horizontal cabling that we have between a wiring closet and a computer. But we often see it across all of our ethernet cables.

Most organizations are going to use the 568B standard for wiring. But you want to be sure if you’re working in a new environment, exactly what type of standard they’re following in their organization. You just have to remember that you can’t wire one side with the 568A standard and the other side with a 568B standard and expect it to work. Those are two very incompatible types. You want to be sure you’re using exactly the same standard on both sides.

Here’s the color schemes for the standards themselves. The 568A is on the left side and the 568B on the right side. And they’re numbered 1 through 8. These are the pins that we use on the end of the RJ45 cable. You can see they’re very similar, especially pins 4 and 5, and 7 and 8, or exactly the same between the two standards.

Where they differentiate is between pins 1, 2, 3, and 6. You can see that they are white and green and green in the A standard for pins 1 and 2, and orange and white and orange on pins 1 and 2 on the B standard. So those pins 1, 2, 3, and 6 are simply switched with the colors, depending on what standards you’re looking at.

Another common copper cabling type is the BNC connector. The B stands for the bayonet, which is this twisted connector at the end that you push in and you twist to lock in place. The NC stands for Paul Neill and Carl Concelman, who came up with this standard for the BNC connector.

For networking we very commonly see BNC being used for DS3 WAN links, which are brought in on these coax cables. These are often very rigid and bulky cables to work. You’re very often are using now smaller, twisted pair cables or even fiber connections, instead. Another very popular connector a networkink– especially on cable modem connections– is the F-connector. We often see this being used with cable television in sending video signals through connection. But because you have so many cable companies now providing internet access, we are sending our internet connections over these RG-6 cables and these threaded F-connectors.

3 thoughts on “Network Connectors – CompTIA A+ 220-901 – 2.1”

  1. Your video states that you can’t wire a cable using 568A on one side and 568B on the other. That it just won’t work. Actually, this configuration is used all the time. It’s called a crossover cable. It would also work on devices that use MDIX.

    1. That’s a common misnomer. There is a single type of crossover cable that coincidentally has the same wiring as 568A on one side and 568B on the other, but that is not the definition of a crossover cable. For example, a gigabit Ethernet crossover cable is not wired by using 568A on one side and 568B on the other.

      1. The Deplorable Russ in OR

        Thank you for the reply. I knew it would change when they started using all 8 wires. Some of the Network+ texts and CCENT texts explained the pinouts for 4 wire crossovers and they had the 568A on one end and 568B on the other. I’m just trying to make sure I have this dialed in, because I’m having to re-take the A+ for a degree program, but will then switch to Networking courses.

        I’ve used your videos to prep for A+ and Network+ in the past. I’m glad you added Security+. Thank you again for your training courses.


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