3.1 Explain basic cable types and their connectors, features, and their purposes.
- Network cables
- Cat 5
- Cat 5e
- Cat 6
- Cat 6A
- Shielded Twisted Pair
- Direct Burial
- Unshielded Twisted Pair
- Peripheral Cables
- USB 2.0
- USB 3.0
- Video Cables
- High-Definition Multimedia Interface (HDMI)
- Digital Video Interface (DVI)
- Video Graphics Array (VGA)
- Connector Types
- F Type
- Straight Tip (ST)
- Subscriber Connector (SC)
- Lucent Connector (LC)
- Punchdown Block
- Lightning Port
Network Cables – Copper
There are two types of network cable: Copper and Fiber. When do we use copper and when do we use fiber?
Most of the copper wiring in use is Unshielded Twisted Pair (UTP). This is a standard ethernet cable that contains eight wires, twisted into four pairs. The twists are designed to cancel out most forms of electromagnetic interference (from radio waves and nearby power lines). UTP can be run up to 100 meters.
For more advanced applications, we can use a Shielded Twisted Pair (STP) cable. This is also known as F/UTP cable. The difference is that the STP cable contains a foil around the wires. The foil blocks out even more electromagnetic interference than the twists. The foil connects to the termination point on each end of the cable and acts as an electrical ground. STP cable is used in applications such as video transmission and in areas where there is a large amount of interference. If we peel back a cable, we can see the difference.
If we went crazy, we could buy a cable that had a separate shield around every pair. The shield protects the wires from electromagnetic interference. It also protects individual wire pairs from cross-talk (interference from a neighboring wire pair).
Most device network interfaces accept a copper (UTP or STP) connection. That includes switches, IP cameras, computers, and VoIP phones.
Another form of copper wiring is coaxial. Coaxial wiring can be run up to 500 meters. It consists of a central conductor with a braid wrapped around it. The braid shields the central conductor from electromagnetic interference that could disrupt the signal.
Coaxial cable can be run up to 500 meters. It is used to connect older analog cameras, satellite systems, antennas, and cable modems.
There are several categories of ethernet cable as you will see in the following table
Fiber optic cable can be run longer distances than copper. It also has a larger bandwidth. But fiber is more difficult to install than copper. It requires specialized equipment to test and terminate. A fiber optic cable uses light to transmit data while an ethernet cable uses electricity.
We can’t connect a fiber optic cable to standard host devices. For example, a VoIP phone or computer will not have a fiber optic connector. If we ran a fiber optic cable to a far away computer, we would need a device called a media converter to convert the fiber to copper. We also can’t use PoE over a fiber optic cable (there are some technologies that combine a fiber optic cable with a copper cable to provide both data and PoE, but they are not common).
Fiber comes in two forms: single-mode, and multimode. Single mode cable can be run upwards of 200 km. The light signal travels down the center of the cable as a single signal. Multimode cable can be run up to 1 km. The light bounces up and down inside the cable.
A single copper contains eight wires. When connected, the copper cable carries data in multiple directions. But a single fiber optic cable can contain multiple strands. A single strand carries data in only one direction (advanced technology allows us to transport data in both directions on the same strand at the same time, and split a signal into multiple circuits, but that is beyond the scope of this book). When we peel back the cable, we find multiple strands, which are color coded. We need at least two strands to make a circuit and carry data. Most common sized fibers have six or twelve strands.
Plenum vs PVC
A Plenum space is a part of the building that circulates air for heating, ventilation, and air conditioning systems (HVAC). It includes the ventilation system. In a building with a dropped ceiling or drywall ceiling, it may include the space above the ceiling.
The fire code and other building codes require that cable installed in the plenum space is “plenum rated”. A plenum-rated cable does not burn easily, and when it does, it does not create toxic fumes, which could poison the building’s occupants.
A cable that is plenum-rated will be marked with the letters “CMP”.
A “riser rated” cable is manufactured to lower standards from a plenum rated cable. It can be run between different floors of a building but must not be installed in an air space. It is marked with the letters “CMR”.
A PVC cable is not manufactured to withstand any fire and can only be run on a single floor of a building, and not inside a plenum space.
We should always install plenum-rated cable. If we only install plenum-rated cables, we don’t have to worry if the space we installed the cable is plenum or not. We also don’t have to worry about whether the area’s classification is changed in the future. We also don’t have to worry about keeping stock of multiple types of cable.
The cost of a plenum rated cable is about 50% more than the cost of a PVC cable, but the greatest cost of a cable installation is labor. Thus, using plenum cable instead of riser cable doesn’t substantially increase the installation cost.
Another type of cable is outdoor rated cable. Outdoor rated cable contains a thicker jacket that is resistant to UV light and is filled with a gel that helps resist damage due to cold or hot weather. An indoor rated cable will not survive outdoors because the sun will break it down, the cold weather will make it brittle, and animals will chew on it.
There are two methods for terminating a cat5e/cat6/cat6A cable. The methods are known as 568A and 568B. Remember that the ethernet cables contain 4 pairs of wires (colored as blue, orange, green, brown). The difference between 568A and 568B is that the position of the orange and green wires is swapped.
If we look at the side of a cat5e jack, we can see that the manufacturer has marked a color code for “A” style terminations and “B” style terminations. On the other side of the jack, we would see similar markings.
We should insert the wire into the correct colored slot on the jack or patch panel and then terminate it with a punch-down tool of the appropriate size.
We could also terminate the cable to a male connector. The male connectors follow the same color code as the female connectors. We use a tool called a crimper to secure the wires inside the connector.
Both 568A and 568B are acceptable termination methods. A cable should be terminated with the same method on both sides. An organization may require the cable to be terminated using a specific method. Most private organizations prefer 568B, and most governments prefer 568A. 568A was invented first and was recommended for backwards compatibility with analog devices, which is why the government adopted it.
If we terminate the cable in the same order on both ends, we call it a straight through cable. If we terminate the cable as 568A on one end and 568B on the other end, the orange and green pairs become crossed. This is called a crossover cable.
Why would we make a cross-over cable? Network devices usually use the orange and green pairs to communicate. A device like a switch transmits over the orange pair and listens on the green pair. A device like a computer transmits on the green pair and listens on the orange pair. If we connect a computer to a switch, collisions do not take place because each uses a different pair to talk and listen.
If we want to connect two computers together or two switches together, they will try to talk on the same pair and listen on the same pair. No data will get through. Both devices will talk on the green pair and listen on the orange pair (the device doesn’t know the color of the wire; it only knows the position of the wire – if you punched the blue wire in the orange wire’s spot, the device would communicate over the blue wire).
So, if we use a cross-over cable, then one switch will transmit over the orange pair (wires 1 and 2) and listen over the green pair (wires 3 and 6). The other switch will transmit over the green pair (wires 3 and 6) and listen over the orange pair (wires 1 and 2).
But we don’t need crossover cables to connect switches anymore. If two modern switches are connected via a straight through cable, they will immediately detect the collision and agree on which switch will use which wire pairs.
After we install the cable, we must terminate it somehow. We must put a connector on the end so that we can plug it into something. A copper connector can be male or female.
In a telecommunications system, we might use a wall-mounted block known as a 66, 110, or BIX block. Again, the name refers to the shape of the wire termination points. Below is a 66 block. The blocks are used to cross connect cables. Wires coming from outside the system (wiring coming from a phone system or wiring coming from outside the building) are normally punched down to the left side of the panel. Building wiring is punched down to the right side. We add jumpers (the metal pieces in the middle of the block) to cross connect one side of the block to the other. Jumpers are also known as bridging clips.
The telecommunications blocks allow us to cross-connect a single wire at a time. We can connect many different types of copper wire to the block, including cat5e, cat6, or cat3.
A 110 block is below
We also have connectors for fiber optic cables. We can purchase adapters for any type of fiber connector. Notice that fiber cables do not have female connectors, only male. We can convert a male connector to a female connector by connecting it to a coupler.
After a fiber connector is manufactured, it is polished. The angle at which it is polished affects its data transmission. Two fiber connectors must be mated together so that they can transmit data.
Let’s look at video cables now. Video cables generally come terminated from the factory.
In general, we can convert any signal to any other signal. Any digital conversion (DVI to HDMI, HDMI to Mini-HDMI, etc. requires a simple adapter. Converting from an analog signal to digital or from digital to analog requires an electronic converter. The converter may obtain power from a USB port, video signal, or power outlet
Other Cable Types
There are many other types of connectors, and these are the most common
Common HDD Cables
There are several types of hard drive cables.
There are many adapters, but these are the most important.