Structured Cabling Defined Part 2 - Types of Cables Last month we introduced to you the concept of structured cabling and how it is important in today’s environment where the Internet is used not just for computers and data. VoIP and IP communication, as well as video signals also use your internal cabling and the Internet. In a computer only network, data transfer between computers is done with trailing checks that is used by the receiving station to test the validity of the data received. If what is called ‘checksum’ returns an error, the receiving station will reject the data, and send a signal to the sending station to resend the data. All this is done extremely fast and you will not even notice it. When you are using the same network for voice and video, everything happens in real time and there is no ‘send me the data again’ concept. What you will see in video are blips and interference, and what you will hear in voice is noise and maybe inaudible or incomprehensible voice signals. We do not want that, do we? So it is important that every part of the network connectivity works impeccably. One of the important components of a network is the cable used. Let us now understand what a cable is and how to choose one for your requirement.
Networking & Cables Networking helps to connect different end points and transfer data. Within an office or a building, cable is the most common medium in which information is transmitted from one network device to another one. Different types of cables are used in a LAN. A particular network may use a single type of cable while another network may deploy variety of cables. The type of cable required for a network depends upon its topology, protocol and size. Success of any computer networking depends upon the structure and cabling of the total system. Let us look at three main cable types.
This type of cable has been in use for a long time, and is slowly losing it’s relevance. In a coaxial cable, there is a single copper conductor at the center. A plastic layer between the braided metal shield and the center conductor provides
insulation. This metal shield is useful as it blocks any interference from outside. Coaxial cable can work across long distances and have been used by TV companies to carry their signals to your home. There are 2 types of coaxial cables which are normally used, namely - thin coaxial and thick coaxial. In terms of networks, thin cables were used in what were called thinnet, and while the thicker cables were used in thicknet. In thicknet, the conductor diameter is 2.17 mm. Such cables are used in 10Base5 networks. The 10 refers to 10 Mbps and the 5 refers to a maximum length of 500 meters. In thinnet, conductor diameter is 0.9 mm. This cable is used in 10Base2 networks. The 10 refers to 10 Mbps and the 2 refers to maximum length of 200 meters. Coaxial cables are connected using a BNC connector
Twisted Pair (TP) cables Because coaxial cables are slow and unwieldy, it became difficult to install them in local area networks and inside server rooms. As network connections were speeding up, cable manufacturers went back to a concept invented by Alexander Graham Bell â€“ the concept of twisted pair cables. In this type of cable, two conductors of a single circuit are twisted together for cancelling out external interferences such as EMI. One of the main advantages of a twisted pair is that it is very thin and extremely flexible. In highly congested networks, you can run more lines through the same ducts as compared to coaxial cables. And, of course, because of higher bandwidth, twisted pair move data at much higher speeds. Twisted pair cables are grouped into categories based on their usage and speed. The various grouping, bandwidth, applications, and speeds are shown below. Name Level 1 Level 2 Cat3 Cat4 Cat5 Cat5e Cat6 Class F Class Fa
Type UTP UTP UTP UTP UTP UTP S/FTP
Bandwidth 0.4 MHz 4 MHz 16 MHz 20 MHz 100 MHz 100 MHz 500 MHz 600 MHz 1000 MHz
Applications Telephone and modem lines Older terminal systems, e.g. IBM 3270 10BASE-T and 100BASE-T4 Ethernet 16 Mbit/s Token Ring 100BASE-TX & 1000BASE-T Ethernet 100BASE-TX & 1000BASE-T Ethernet 10GBASE-T Ethernet 10GBASE-T Ethernet Telephone, CCTV, 1000BASE-TX in the same cable. 10GBASE-TEthernet.
Speed 1 Mbps 4 Mbps 16 Mbps 20 Mbps 100 Mbps 1000 Mbps 10,000 Mbps 10 Gbps 40 Gbps
We have introduced a new concept here and that is called bandwidth. What is a bandwidth and should I worry about it? Actually no, though there is no harm in understanding the term and showing off to someone in a party. To understand the term, let us understand how a copper wire works. A copper wire carries data from one end using electrical currents. In electrical parlance, a bandwidth is the width of the range of frequencies that a signal uses. The frequency of all signals is measured in hertz (Hz) which is the number of cycles of change per second. A voice signal has a bandwidth of roughly 3,000 Hz or 3 kHz. A video signalâ€™s bandwidth is 6 million Hz or 6
MHz, some 2,000 times higher. So the higher the bandwidth of the cable, the more the data it can carry. There are two broad categories of twisted pair cable – unshielded and shielded.
Unshielded Twisted Pair (UTP) cable
Unshielded twisted pair is the most commonly used in telephone cables, computer networks, and even in video applications such as security cameras. These cables are typically made with copper wires measured as 22 or 24 AWG with insulation typically made from polyethylene (FEP) and the total package covered in a slight hard polyethylene jacket. The Cat5 cable which is the most common form of cable used for computer networking is made of UTP cables. UTP cables are generally used in short lengths such as inside a building, or within a server room.
Shielded Twisted Pair (STP) cable UTP cable is susceptible to radio and electrical frequency interference. Though more expensive, Shielded Twisted Pair (STP) cables are a better option. Shielded Twisted pair cables can also be useful in extending maximum distance of cables. Shielded cable is available in 3 configurations:
Every pair of wire is separately shielded with foil All wires having a braid shield inside the wire jacket Each individual pair having a shield, besides having another around the whole group of wires
Fiber Optic Cable Another type of cable is Fiber Optic. It consists of a center glass core surrounded by numerous layers of protective material. Instead of using electricity to carry signals, it used light pulses to carry signals. Because of this basic difference, fiber optic cables are completely immune to any electro-magnetic interference. It is hence the ideal cabling solution for certain environment where interferences are prevalent and cannot be avoided. It is also immune to moisture and lightning.
There are 2 types of fiber optic cables available â€“ single-mode and multi mode. Single mode has one narrow glass core with a core to cladding diameter ratio of 9/125 microns. A single beam of light pulse is used in this case. This is more reliable and can be used for long distances. Multi-mode has larger inner core and allows multiple modes or pulses of light to traverse at the same time. This enables more data to pass through at the same time, though over short distances. The core to cladding ratio is usually between 50/125 to 62.5/125. Fiber optic cables are generally more expensive in comparison to other options, but carry a much larger amount of data at very high speeds. Just to give you a sample, depending upon construction and other parameters, a fiber optic cable can carry data between 15 Trillion bits per second to 1.05 Peta bits per seconds. The physical limits of fiber optical have not yet been reached. In a recent experiment in UK, scientists were able to transmit data at 10 terabytes per second. To give you an idea, a regular fiber optic cable can carry 90,000 TV channels simultaneously without any loss! Wow! Next month we will look at other aspects of networking such as standards, vertical and horizontal cabling, security, etc.
Conclusion Cables are an important part of any networking. Today you have both twisted pair and fiber optic cables that can handle speeds far greater than any you can throw at them. Cat6 cables are easily available as are optical fiber cables. To keep costs down, you have the flexibility to wire different parts of your network with different cables. For example, if you have a conference room with video and other capabilities, that can be wired to the server and router with an optical fiber. That way your video conferences will always go without a hitch.
About Tri-Tel Tri-Tel offers high quality structured cabling in Elgin & Shaumburg. As part of setting up a network for you, we will discuss and then choose the best quality parts including cables to suit your requirements. With IP/VoIP, and video communication becoming common, it is imperative
that the correct cable be chosen for your requirements. Trust Tri-Tel with its vast experience to do that