CHAPTER TWO Cabling, Connectors, and Ethernet Standards

1 2 CHAPTER TWOC abling, Connectors, andEthernet standard cable types and their :.CAT3, CAT5, CAT5e, , fiber, single-mode vs. :.Transmission immunity (security, EMI). common connector 2: Cabling, Connectors, and Ethernet a scenario, differentiate and implement appropriate wiring vs. LAN technology types and :. :. components of wiring and horizontal cross pairGeneral Media wiring wiring terminationWhat You Need to common media the relationship between media and the two signaling methods used on the three media dialog the characteristics of IEEE Standards , including , , , the commonly implemented network the various connectors used with network it comes to working with an existing network or implementing a new one,you need to be able to identify the characteristics of network media and theirassociated cabling.

2 This CHAPTER focuses on the media and connectors used intoday s networks and how they fit into wiring addition to media and connectors, this CHAPTER identifies the characteristics ofthe IEEE standard and its Media ConsiderationsIn addition to identifying the characteristics of network media and their associ-ated cabling, the Network+ exam requires knowledge of some general terms andconcepts that are associated with network media. Before looking at the individ-ual media types, it is a good idea to first have an understanding of some gener-al media 2: Cabling, Connectors, and Ethernet StandardsBroadband Versus BasebandNetworks employ two types of signaling methods:.Baseband transmissions: Use digital signaling over a single on baseband transmissions is bidirectional, allowing sig-nals to be sent and received, but not at the same time.

3 To send multiplesignals on a single cable , baseband uses something called Time DivisionMultiplexing (TDM). TDM divides a single channel into time transmissions: In terms of LAN network Standards , broad-band transmissions use analog transmissions. For broadband transmis-sions to be sent and received, the medium must be split into two chan-nels. Multiple channels are created using Frequency Division Multiplexing(FDM).Simplex, Half Duplex, and Full DuplexSimplex, half duplex, and full duplex are referred to as dialog modes, and theydetermine the direction in which data can flow through the network media:.Simplex modeallows for one-way communication of data through the net-work, with the full bandwidth of the cable being used for the transmit-ting signal. One-way communication is of little use on LANs, making itunusual at best for network more common is half-duplex mode, which accommodates transmittingand receiving on the network, but not at the same time.

4 Many networksare configured for half-duplex preferred dialog mode for network communication is full-duplexmode. To use full duplex, both the network card and the hub or switchmust support full duplexing. Devices configured for full duplexing cantransmit and receive simultaneously. This means that 100 Mbps networkcards theoretically can transmit at 200 Mbps using full-duplex InterferenceDepending on where network cabling (commonly called media) is installed,interferencecan be a major consideration. Two types of media interference canadversely affect data transmissions over network media: electromagnetic inter-ference (EMI) and Media Considerations47 EMI is a problem when cables are installed near electrical devices, such as airconditioners or fluorescent light fixtures.

5 If a network medium is placed closeenough to such a device, the signal within the cable might become media vary in their resistance to the effects of EMI. Standard unshield-ed twisted pair (UTP) cable is susceptible to EMI, whereas fiber cable , with itslight transmissions, is resistant to EMI. When deciding on a particular medium,consider where it will run and the impact EMI can have on the second type of interference iscrosstalk. Crosstalk refers to how the data sig-nals on two separate media interfere with each other. The result is that the sig-nal on both cables can become corrupt. As with EMI, media varies in its resist-ance to crosstalk, with fiber-optic cable being the most ALERTFor the Network+ exam, remember that fiber-optic uses optical signals, not electrical,giving it a greater resistance to EMI and CrosstalkMore information on media interference such as crosstalk can be foundin CHAPTER 11, Troubleshooting and Supporting the Network.

6 AttenuationAttenuationrefers to the weakening of data signals as they travel through a medi-um. Network media vary in their resistance to attenuation. Coaxial cable gener-ally is more resistant than UTP, STP is slightly more resistant than UTP, andfiber-optic cable does not suffer from attenuation at all. That s not to say that asignal does not weaken as it travels over fiber-optic cable , but the correct termfor this weakening is chromatic dispersionrather than s important to understand attenuation or chromatic dispersion and the maxi-mum distances specified for network media. Exceeding a medium s distancewithout using repeaters can cause hard-to-troubleshoot network problems. Arepeater is a network device that amplifies data signals as they pass, allowingthem to travel farther.

7 Most attenuation- or chromatic dispersion-related diffi-culties on a network require using a network analyzer to detect 2: Cabling, Connectors, and Ethernet StandardsData Transmission RatesOne of the more important media considerations is the supported data transmis-sion rate or speed. Different media types are rated to certain maximum speeds,but whether they are used to this maximum depends on the networking standardbeing used and the network devices connected to the transmission rate of media is sometimes incorrectly called the bandwidth. In truth,the term bandwidth refers to the width of the range of electrical frequencies or the num-ber of channels that the medium can rates normally are measured by the number of data bits that cantraverse the medium in a single second. In the early days of data communica-tions, this measurement was expressed in bits per second (bps), but today s networksare measured in Mbps (megabits per second) and Gbps (gigabits per second).

8 The different network media vary greatly in the transmission speeds they sup-port. Many of today s application-intensive networks require more than the10 Mbps offered by the older networking Standards . In some cases, even100 Mbps, which is found in many modern LANs, is simply not enough to meetcurrent network needs. For this reason, many organizations deploy 1 Gbps net-works, and some now even go for 10 Gbps MediaWhatever type of network is used, some type of network medium is needed tocarry signals between computers. Two types of media are used in networks: cable -based media, such as twisted pair, and the media types associated withwireless networking, such as radio networks using cable -based media, there are three basic choices:.Twisted pair and coaxial cables both use copper wire to conduct the signals elec-tronically; fiber-optic cable uses a glass or plastic conductor and transmits thesignals as Media49 For many years, coaxial was the cable of choice for most LANs.

9 Today, twistedpair has proven to be far and away the cable medium of choice, thus retiringcoaxial to the confines of storage closets. Fiber-optic cable has also seen its pop-ularity rise, but because of cost it has been primarily restricted to use as a net-work backbone where segment length and higher speeds are needed. That said,fiber is now increasingly common in server room environments as a server-to-switch connection method, and in building-to-building connections in what arecalled metropolitan area networks (MANs). For more information on MANs,see CHAPTER 1, Introduction to Networking. The following sections summarize the characteristics of each of these CablingTwisted-pair cabling has been around for a very long time. It was originally cre-ated for voice transmissions and has been widely used for telephone communi-cation.

10 Today, in addition to telephone communication, twisted pair is the mostwidely used medium for popularity of twisted pair can be attributed to the fact that it is lighter, moreflexible, and easier to install than coaxial or fiber-optic cable . It is also cheaperthan other media alternatives and can achieve greater speeds than its coaxialcompetition. These factors make twisted pair the ideal solution for most net-work main types of twisted-pair cabling are in use today: Unshielded Twisted Pair(UTP)and Shielded Twisted Pair (STP). UTP is significantly more common thanSTP and is used for most networks. Shielded twisted pair is used in environ-ments in which greater resistance to EMI and attenuation is required. Thegreater resistance comes at a price, however.