CompTIA+ Networking Concepts

Introduction What is a Network?Linking two or more computing devices together, usually for sharing data (files or folders) or resources (mail servers, file server, printers, Scanners etc.) is popularly known as a Network.If there are a number of computers at home or in an organization, connecting them together can bring substantial benefits. For example, you can share printers, internet connections and files such as photos or music etc.Networks are built using both computer hardware and software. Networks can be categorized into different types like LAN, WAN and MAN according to the geographic area they span.In this module, you will be learning about the various types of network cables, their connectors, the technologies available, their characteristics, IP addressing etc., apart from the working of a network.Before we start the module topics, let's see how much you already know about the basic computer networking concepts.

Cable Types What is Network Cabling?Cable is the medium through which data is transmitted from one network device to another. There are several types of cables, which are commonly used with LANs. The growth of Local Area Networks (LANs) and client server computing has produced a great increase in the amount of cabling used.In many cases, a network will use a variety of cable types. The type of cable chosen for a network is related to the network's topology, protocol, and size. Also the common transmission losses such as attenuation have to be taken care of while choosing the type of cable used.

Cable Types (Cont...) A cable is a group of insulated conductors enclosed within an Insulator. The main function of a cable is transmitting signal from one point to another. They can be broadly categorized into 5 types depending on their attenuation, cost, immunity to EMI, skilled labor required for installation etc.Given below is the list of cable types used in networking.

1. Coaxial
   1. RG6
   2. RG8
   3. RG58
   4. RG59
2. Plenum/PVC
3. UTP
   1. CAT3
   2. CAT5/e
   3. CAT6
4. STP
5. Fiber
   1. Single-mode
   2. Multi-mode

Let us learn more about each of these cable types.

Coaxial Cable What is a Coaxial Cable?Coaxial cable is commonly used in the cable television industry. This has also gained popularity in use for computer networks, such as Ethernet networks. Coaxial cable is highly resistant to signal interference and can support greater distance between network devices than twisted pair cable.Coaxial cable consists of a single core copper wire surrounded by an insulator and enclosed in a copper mesh, finally covered inside an outside insulation. The Coaxial Cable consists of the following types:RG (Radio Guide) 6: These are high quality and low transmission loss Cables generally used in areas where over-the-air signals may cause interference for Digital Cable and Satellite TV applications.RG8: These cables are used in "10base5" "Ethernet" networks because of its great flexibility with low transmission losses. RG58: RG58/U Coaxial Patch Cables are used for ThinNet.RG59: RG59/U BNC Patch cables are used for video applications such as CCTV, home theatre, and much more.The main features co-axial cable:

• When compared to twist pair cable a coaxial cable can support greater cable lengths between network devices.
• They are highly resistant to signal interference.
• It costs less that other cables.
• Not flexible and it is more difficult to terminate.

Plenum/PVC What is Plenum Cable?Plenum grade cable is a cable that uses fire resistant material such as Teflon for insulation. This type of material in the insulation minimizes the amount of smoke in case of fire. However, plenum cabling are more expensive and less flexible than a PVC cable. This type of cable is generally used in space reserver for air circulation in air conditioning and heating systems.PVCPVC (Polyvinyl Chloride) is a form of plastic, which is widely being used in the manufacture of cable insulation.The advantages of PVC cables are that they are flexible, and economical. However when it burns, it produces poisonous Halogen gases such as fluorine, chlorine, bromine, and iodine.

Twisted Pairs The twisting of two insulated wires around each other is known as twisted pair cables. Cables that use twisted pair of wires reduce the Crosstalk between them to a great extent.As shown in the image, the pair of wires may be surrounded either by a shield, or similar pairs of wires. Each pair is uniquely color coded when packaged in multiple pairs. Different uses such as Analog, Digital, and Ethernet require different pair multiples.Twisted pair wiring is commonly used to connect telephones and in computer network technology and are classified according to their maximum transmission frequencies. Today, there are basically only two types used and they are Cat3 and Cat5.Some features of Twisted pair cabling are:

• It is flexible and easy to terminate.
• For Cat 5e/6/7 UTP the maximum segment length is 100 meters.

10BaseT refers to the specifications for unshielded twisted pair cable (Category 3, 4, or 5) carrying Ethernet signals. Category 6 is relatively new and is used for gigabit connections.Twisted pair cables are available in two variants:

1. Shielded Twisted Pair (STP) and
2. Unshielded Twisted pair (UTP)

Let us look into the details of these two variants.

STP Shielded Twisted Pair (STP)In STP each of the two copper wires are twisted together and coated with a dielectric insulator which functions as ground for the wires. The extra shielding in STP wiring protects the transmission line from the leaking of electromagnetic interference from and into the cable. STP cabling is often used in Ethernet networks, especially fast data rate Ethernets with Speeds in the range of 10 to 1000 Mbps.The notable features of STP are:

• It prevents interference efficiently than UTP, but it is more expensive and difficult to install.
• The attenuation of UTP cable is much higher than co-axial or shielded twisted pair cable.

The drawbacks are:

• If the metallic shielding is not grounded properly at both ends, the shield behaves as an antenna and picks up unwanted signals.
• Because of its cost and difficulty with termination, STP is rarely used in Ethernet networks.

UTP (Cat 3, Cat 5/e, Cat 6) Unshielded Twisted Pair (UTP)UTP using the 10BaseT specification is the most used type of twisted pair cable in Category 5 cabling. In this cable though each individual wire is not insulated, each wire is twisted around each other.The main disadvantage of UTP is that it is more susceptible to electrical noise and interference than other types of networking media, and the signal needs to be boosted at shorter distances than that of coaxial and fiber optic cables. The maximum cable length is 100 meters or 328 feet (10BaseT).Let us see the commonly used types of UTP cabling:

• Category 3/Voice is commonly used in 10BaseT networks; it can transmit data at speeds up to 10 Mbps.
• Category 5e/Data can transmit data at speeds up to 1000 Mbps (1 Gbps).
• Category 6/Data is currently the fastest standard for UTP.

Fiber (Single, Multi-mode) What is Fiber-Optic Cable?It is a cabling technology that uses optical fibers to carry digital data signals in the form of modulated pulses of light. The core of fiber-optic cable is made of glass or plastic and the cladding that are enclosed by a protective coating. Outer insulating jacket is made of Teflon or PVC. Kevlar fibers are used to strengthen the cable and prevent from breakages.A brief overview of the advantages of fiber-optic cable over coaxial and twisted pair:

• Speed: Fiber optic networks operate at high speeds in the gigabits range.
• Bandwidth: High-capacity data transmission.
• Distance: Due to lack of attenuation Signals can be transmitted over long distances without using repeaters.
• Resistance: Greater resistance to outside interferences such as radios, motors and electromagnetic noise.
• Expensive and very fragile.

Let us look at the 2 types of fiber-optic cables.

Fiber (Single, Multi-mode) (Cont...) Single-mode Fiber Optic CablesThe Single-mode Fiber (SMF) is a single strand of glass fiber with core diameter less than 10 microns and has one mode of transmission.

• It carries higher bandwidth of data, approximately 50 times more than Multimode Fiber and has speeds up to 25,000 Gbps on paper.
• The SMF is more expensive than the Multimode Fiber Optic Cables and requires a light source with a narrow spectral width for propagation.
• These are normally used for local area networks.

Multi-mode Fiber Optic CablesMulti-mode fiber (MMF) is made of glass fibers with core diameter in the range of 50 to 100 microns and can carry data of more than 5 Gbps, which equals a million megabits.

• It meets the bandwidth needs of the new high performance applications such as Streaming Audio/video, Multimedia, and Networking.
• The industry has come up with next generation of fiber optic patch cable, 10 Gigabit (10GigE). The 10 Gigabit fiber which has a 50um fiber core and provides nearly 3 times more bandwidth than the conventional 62.5um fiber optic patch cables. It is typically used in installations up to 2000 meters in length.
• These are normally used for wide area networks.

RS-232 RS-232RS (Recommended Standard) - 232 is a standard for serial binary data interconnection. It is commonly used in computer serial ports.

• RS-232 also has relatively poor control of signal rise and fall times, which leads to crosstalk problems.
• RS-232 is good for short connections below 15 meters. Because of the unbalance circuits, RS-232 interface cables are usually not constructed with twisted pair.
• The usage of unbalanced circuits is responsible for RS-232 being susceptible to problems due to ground potential shifts among two devices.

BNC The BNC (British Naval Connector) is a standardized connector used with Thinnet and coaxial cable.

• It is used to connect a computer to a coaxial cable in a 10BASE-T Ethernet network. The 10BASE-2 is a 10 MHz baseband cable network extending up to 180 meters the 2 is the rounding up to 200 meters without using a repeater.
• The wire in this type of Ethernet is a thin 50-ohm, base-band coaxial cable.
• The BNC connector is simpler to use and less expensive than other types of coaxial connectors.

Some of the important components in the BNC family are:

1. The BNC cable connector: It is either soldered or crimped to the end of a cable.
2. The BNC T connector: It joins the network interface card in the computer to the network cable.
3. The BNC barrel connector: It is used to join two lengths of thinnet cable to make one longer length.
4. The BNC terminator: It closes each end of the bus cable to absorb unwanted signals. Without BNC terminators, a bus network will not function.

RJ-45 What does RJ-45 mean?

• RJ (Registered Jack)-45 also known as Cat 5e jacks or Cat 5e plugs is the standard connector used for Unshielded Twisted-Pair cable.
• It is most commonly used for 10Base-T (10 megabit baseband over twisted-pair copper wire) and 100Base-TX Ethernet connections. Also used in network cabling and in telecommunication applications.
• RJ-45 jacks and plugs have 8 pins. It is also referred to as 8P8C connectors. This stands for 8 Position that describes the width 8 Conductor.

AUI AUI (Attachment Unit Interface)

• AUI is a 15-pin connector that is used to attach coaxial, fiber optic, or twisted pair cables that are found on Ethernet cards.
• In a network the AUI is the physical interface between a network card and Ethernet cable.
• AUI using a D-shape connector is an interface from a computer to an Ethernet. The AUI Interface that plugs into an AUI cable, which can be up to 50m long is fitted to the computer or the client in a 10Base5 Ethernet installation.
• In 10Base-5 Ethernet networks, a short cable is used to connect the AUI with a transceiver on the main cable. In 10Base-2 Ethernet, the NIC connects directly to the Ethernet coaxial cable

ST/SC

ST and SC connectorsThere are many types of plugs and sockets available to connect optical fibers; the most common connector used with fiber optic cable are:

• ST (Straight Tip) connector: It is barrel shaped and is similar to a BNC connector.
• SC (Subscriber Connector or Standard Connector): Easier to connect in a confined space and it is squared faced.

Attaching a connector to an optical fiber takes much effort than copper wire connectors because the ends of the fiber usually have to be carefully cemented and then polished in order to let the maximum light pass through.The SC and ST connectors are field-installable, multimode fiber optic connectors. The ST connector is used only on NICs for fiber optic networks such as 10BaseFL or 100BaseFX.