ELX 222B Data Cabling & Structure Wiring System PDF

ELX 222B DATA CABLING and STRUCTURE WIRING SYSTEM ELECT 122  Course Description This subject deals with the basics of data cabling, including topics such as: The golden rules of data cabling The...

ELX 222B DATA CABLING and STRUCTURE WIRING SYSTEM ELECT 122  Course Description This subject deals with the basics of data cabling, including topics such as: The golden rules of data cabling The importance of reliable cabling The legacy of proprietary cabling systems The increasing demands on data cabling to support higher speeds Cable design and materials used to make cables Types of communications media Limitations that cabling imposes on higher-speed communications The future of cabling performance ELECT 122  COURSE OUTCOMES 1. Apply the techniques in proper data cabling. 2. Differentiate the types of data cabling. 3. Apply the data cabling techniques in sharing the resources over the network. ELECT 122  GENERAL GUIDELINES/CLASS RULES 1. Make-up exams and quizzes will be given only with prior approval of the instructor and under exceptional circumstances. For excused absences during the exam, the university policy will be followed. 2. Students are not allowed to leave the classroom once the class has started, unless extremely necessary. Students who leave the classroom without any valid reason will be marked absent. 3. Students are expected to comply strictly with the university rule on dress code, class tardiness and attendance. 4. Cell phones or any e-gadgets must be switched off or put in a silent mode during class hours, except when allowed by the instructor for activities that require use of such gadgets. 5. Homework’s or projects submitted later than the two-week allowance or more on exceptional cases will not anymore be accepted. Students are expected to maintain complete honesty and integrity in their academic work. Acts of academic dishonesty, such as cheating, plagiarism, or inappropriately using the work of others to satisfy course requirements, will not be tolerated and may result in failure of the affected assignments and/or ELECT 122 failure of this class.  Introduction To Data Cabling Data cabling! It’s just wire. What is there to plan?” Too few people understand the importance of a reliable, standards-based, flexible cabling system. Fewer still understand the challenges of building a high-speed network. Some of the technical problems associated with building a cabling system to support a high-speed network are comprehended only by electrical engineers. And many believe that a separate type of cable should be in the wall for each application (PCs, printers, terminals, copiers, etc.). Data cabling has come a long way in the past 20 years. ELECT 122  Introduction To Data Cabling You are probably thinking right now that all you really want to know is how to install cable to support a few 10Base- T workstations. Words and phrases such as attenuation, crosstalk, twisted pair, modular connectors, and multimode optical-fiber cable may be completely foreign to you. Just as the world of PC LANs and WANs has its own industry buzzwords, so does the cabling business. In fact, you may hear such an endless stream of buzzwords and foreign terminology that you’ll wish you had majored in electrical engineering in college. But it’s not really that mysterious and, armed with the background and information we’ll provide, you’ll soon be using cable speak like a cabling ELECT 122 professional.  The Golden Rules of Data Cabling Listing our own golden rules of data cabling is a great way to start this chapter and the book. If your cabling is not designed and installed properly, you will have problems that you can’t even imagine. From our experience, we’ve become cabling evangelists, spreading the good news of proper cabling. What follows is our list of rules to consider when planning structured cabling systems: Networks never get smaller or less complicated. Build one cabling system that will accommodate voice and data. Always install more cabling than you currently require. Those extra outlets will come in handy someday. Use structured-cabling standards when building a new cabling system. Avoid anything proprietary! ELECT 122  The Golden Rules of Data Cabling Quality counts! Use high-quality cabling and cabling components. Cabling is the foundation of your network; if the cabling fails, nothing else will matter. For a given grade or category of cabling, you’ll see a range of pricing, but the highest prices don’t necessarily mean the highest quality. Buy based on the manufacturer’s reputation and proven performance, not the price. Don’t scrimp on installation costs. Even quality components and cable must be installed correctly; poor workmanship has trashed more than one cabling installation. Plan for higher speed technologies than are commonly available today. Just because 1000Base-T Ethernet seems unnecessary today does not mean it won’t be a requirement in five years. Documentation, although dull, is a necessary evil that should be taken care of while you’re setting up the cabling system. If you wait, more pressing concerns may cause you to ignore it. ELECT 122  The Importance of Reliable Cabling We cannot stress enough the importance of reliable cabling. Two recent studies vindicated our evangelical approach to data cabling. The studies showed: Data cabling typically accounts for less than 10 percent of the total cost of the network infrastructure. The life span of the typical cabling system is upwards of 16 years. Cabling is likely the second most long-lived asset you have (the first being the shell of the building). Nearly 70 percent of all network-related problems are due to poor cabling techniques and cable-component problems. ELECT 122  The Importance of Reliable Cabling We cannot stress enough the importance of reliable cabling. Two recent studies vindicated our evangelical approach to data cabling. The studies showed: Data cabling typically accounts for less than 10 percent of the total cost of the network infrastructure. The life span of the typical cabling system is upwards of 16 years. Cabling is likely the second most long-lived asset you have (the first being the shell of the building). Nearly 70 percent of all network-related problems are due to poor cabling techniques and cable-component problems. If you have installed the proper Category or grade of cable, the majority of cabling problems will usually be related to patch cables, connectors, and termination techniques. The permanent portion of the cable (the part in the wall) will not likely be a problem unless it was damaged during installation. Regardless of how you look at it, cabling is the foundation of your network. ELECT 122 It must be reliable!  The Cost of Poor Cabling The costs that result from poorly planned and poorly implemented cabling systems can be staggering. One company that had recently moved into a new office space used the existing cabling, which was supposed to be Category 5 cable. Almost immediately, 100Mbps Ethernet network users reported intermittent problems. These problems included exceptionally slow access times when reading e–mail, saving documents, and using the sales database. Other users reported that applications running under Windows 98 and Windows NT were locking up, which often caused them to have to reboot their PC. After many months of network annoyances, the company finally had the cable runs tested. Many cables did not even meet the minimum requirements of a Category 5 installation, and other cabling runs were installed and terminated poorly. Often, network managers mistakenly assume that data cabling either works ELECT 122 or it does not, with no in-between. Cabling can cause intermittent problems.  Is the Cabling to Blame? Can faulty cabling cause the type of intermittent problems that the aforementioned company experienced? Contrary to popular opinion, it certainly can. In addition to being vulnerable to outside interference from electric motors, fluorescent lighting, elevators, cellular phones, copiers, and microwave ovens, faulty cabling can lead to intermittent problems for other reasons. These reasons usually pertain to substandard components (patch panels, connectors, and cable) and poor installation techniques, and they can subtly cause dropped or incomplete packets. These lost packets cause the network adapters to have to time out and retransmit the data. Dropped packets (as opposed to packet collisions) are more difficult to detect because they are “lost” on the wire. When data is lost on the wire, the data is transmitted properly but, due to problems with the cabling, the data never arrives at the destination or it arrives in an ELECT 122 incomplete format.  You’ve Come a Long Way, Baby: The Legacy of Proprietary Cabling Systems Early cabling systems were unstructured, proprietary, and often worked only with a specific vendor’s equipment. They were designed and installed for mainframes and were a combination of thicknet cable, twinax cable, and terminal cable (RS-232). Because no cabling standards existed, an MIS director simply had to ask the vendor which cable type should be run for a specific type of host or terminal. Frequently, though, vendor-specific cabling caused problems due to lack of flexibility. Unfortunately, the legacy of early cabling still lingers in many places. PC LANs came on the scene in the mid-1980s; these systems usually consisted of thicknet cable, thinnet cable, or some combination of the two. These cabling systems were also limited to only certain types of hosts and network nodes. ELECT 122  You’ve Come a Long Way, Baby: The Legacy of Proprietary Cabling Systems As PC LANs became popular, some companies demonstrated the very extremes of data cabling. Looking back, it’s surprising to think that the ceilings, walls, and floor trenches could hold all the cable necessary to provide connectivity to each system. As one company prepared to install a 1,000-node PC LAN, they were shocked to find all the different types of cabling systems needed. Each system was wired to a different wiring closet or computer room and included the following: Wang dual coaxial cable for Wang word-processing terminals IBM twinax cable for IBM 5250 terminals Twisted-pair cable containing one or two pairs, used by the digital phone system Thick Ethernet from the DEC VAX to terminal servers RS-232 cable to wiring closets connecting to DEC VAX terminal servers RS-232 cable from certain secretarial workstations to a proprietary NBI word- processing system Coaxial cables connecting a handful of PCs to a single NetWare server ELECT 122  You’ve Come a Long Way, Baby: The Legacy of Proprietary Cabling Systems Some users had two or three different types of terminals sitting on their desks and, consequently, two or three different types of wall plates in their offices or cubicles. Due to the cost of cabling each location, the locations that needed certain terminal types were the only ones that had cables that supported those terminals. If users moved—and they frequently did—new cables often had to be pulled. The new LAN was based on a twisted-pair Ethernet system that used unshielded twisted-pair cabling called Synoptics Lattisnet, which was a precursor to the 10Base-T standards. Due to budget considerations, when the LAN cabling was installed, this company often used spare pairs in the existing phone cables. When extra pairs were not available, additional cable was installed. Networking standards such as 10Base-T were but a twinkle in the IEEE’s (Institute of Electrical and Electronics Engineers) eye, and guidelines such as the ANSI/TIA/EIA-568 series of cabling Standards were not yet formulated (see the next section for more information on TIA/EIA-568-B). ELECT 122 Companies deploying twisted-pair LANs had little guidance, to say the least.  Proprietary Cabling Is a Thing of the Past The company discussed in the last section had at least seven different types of cables running through the walls, floors, and ceilings. Each cable met only the standards dictated by the vendor that required that particular cable type. As early as 1988, the computer and telecommunications industry yearned for a versatile standard that would define cabling systems and make the practices used to build these cable systems consistent. Many vendors defined their own standards for various components of a cabling system. Communications product distributor Anixter (www.anixter.com) codeveloped and published a document called Cable Performance Levels in 1990, which provided a purchasing specification for communication cables. It was an attempt to create a standard by which cabling performance could be measured. Veterans in the networking industry will remember cables often being referred to as Level 1, Level 2, or Level 3 cables. Anixter continues to maintain the Anixter levels program; it is currently called Anixter Levels XP. ELECT 122  The Need for a Comprehensive Standard Twisted-pair cabling in the late 1980s and early 1990s was often installed to support digital or analog telephone systems. Early twisted- pair cabling (Level 1 or Level 2) often proved marginal or insufficient for supporting the higher frequencies and data rates required for network applications such as Ethernet and Token Ring. Even when the cabling did marginally support higher speeds of data transfer (10Mbps), the connecting hardware and installation methods were often still stuck in the “voice” age, which meant that connectors, wall plates, and patch panels were designed to support voice applications only. The original Anixter Cables Performance Levels document only described performance standards for cables. A more comprehensive standard had to be developed to outline not only the types of cables that should be used but also the standards for deployment, connectors, patch panels, and more. ELECT 122  The Need for a Comprehensive Standard A consortium of telecommunications vendors and consultants worked in conjunction with the American National Standards Institute (ANSI), Electronic Industries Alliance (EIA), and the Telecommunications Industry Association (TIA) to create a Standard originally known as the Commercial Building Telecommunications Cabling Standard or ANSI/TIA/EIA-568-1991. This Standard has been revised and updated several times. In 1995, it was published as ANSI/ TIA/EIA-568-A or just TIA/EIA-568-A. In subsequent years, TIA/EIA-568-A was updated with a series of addenda. For example, TIA/EIA-568-A-5, covered requirements for enhanced Category 5 (Category 5e), which had evolved in the marketplace before a full revision of the Standard could be published. A completely updated version of this Standard was released as ANSI/TIA/EIA-568-B in May 2001. ELECT 122  Cabling and the Need for Speed The past few years have seen some tremendous advances not only in networking technologies but also in the demands placed on them. In the past 20 years, we have seen the emergence of standards for 10Mb Ethernet, 16Mb Token Ring, 100Mb FDDI, 100Mb Ethernet, 155Mb ATM (Asynchronous Transfer Mode), 655Mb ATM, 1Gb Ethernet, 2.5Gb ATM., and 10Gb Ethernet (over optical fiber only as of this writing). Network technology designers are already planning technologies to support data rates of up to 100Gbps. ELECT 122  Cabling @ Work: The Increasing Demands of Modern Applications A perfect example of the increasing demands put on networks by applications is a law firm that 10 years ago was running typical office- automation software applications on its LAN. The average document worked on was about four pages in length and 12KB in size. This firm also used electronic mail; a typical e–mail size was no more than 500 bytes. Other applications included dBase III and a couple small corresponding databases, a terminal-emulation application that connected to the firm’s IBM minicomputer, and a few Lotus 1-2-3 programs. The size of transferred data files was relatively small, and the average 10Base-T network-segment size was about 100 nodes per segment. ELECT 122  Cabling @ Work: The Increasing Demands of Modern Applications Today, the same law firm is still using its 10Base-T and finding it increasingly insufficient for their ever-growing data processing and office-automation needs. The average document length is still around four pages but, thanks to the increasing complexity of modern word processing software and templates, the average document is nearly 50KB in size! Today, the same law firm is still using its 10Base-T and finding it increasingly insufficient for their ever-growing data processing and office-automation needs. The average document length is still around four pages but, thanks to the increasing complexity of modern word processing software and templates, the average document is nearly 50KB in size! ELECT 122  Cabling and the Need for Speed The average number of nodes on a network segment has decreased dramatically, while the number of applications and the size of the data transferred has increased dramatically. Applications are becoming more complex, and the amount of network bandwidth required by the typical user is increasing. Is the bandwidth provided by some of the new ultra-high-speed network applications (such as 1Gb Ethernet) required today? Maybe not to the desktop, but network backbones already take advantage of them. Does the fact that software applications and data are putting more and more of a demand on the network have anything to do with data cabling? You might think that the issue is more related to network- interface cards, hubs, switches, and routers but, as data rates increase, the need for higher levels of performance on the cable also increases. ELECT 122  Types of Communications Media Four major types of communications media (cabling) are available for data networking today: unshielded twisted pair (UTP), shielded or screened twisted pair (STP or ScTP), coaxial, and fiber optic (FO). It is important to distinguish between backbone cables and horizontal cables. Backbone cables connect network equipment such as servers, switches, and routers and connect equipment rooms and communication closets. Horizontal cables run from the communication closets to the wall outlets. For new installations, multistrand fiber-optic cable is essentially universal as backbone cable. For the horizontal, UTP reigns supreme. Much of the focus of this book is on UTP cable. ELECT 122  Twisted-Pair Cable By far the most economical and widely installed cabling today is twisted-pair wiring. Not only is twisted-pair wiring less expensive than other media, installation is also simpler, and the tools required to install it are not as costly. Unshielded twisted pair (UTP) and shielded twisted pair (STP) are the two primary varieties of twisted pair on the market today. Screened twisted pair (ScTP) is a variant of STP. Unshielded Twisted Pair (UTP) Though it has been used for many years for telephone systems, unshielded twisted pair (UTP) for LANs first became common in the late 1980s with the advent of Ethernet over twisted-pair wiring and the 10Base-T standard. UTP is cost effective and simple to install, and its bandwidth capabilities are continually being improved. An interesting historical note: Alexander Graham Bell invented and patented twisted-pair cabling and an optical telephone in the 1880s. During that time, Bell offered to sell his company to Western Union for $100,000, ELECT 122 but it refused to buy.  Twisted-Pair Cable UTP cabling typically has only an outer covering (jacket) consisting of some type of nonconducting material. This jacket covers one or more pairs of wire that are twisted together. Four-pair cable is the most commonly used horizontal cable in network installations today. The characteristic impedance of UTP cable is 100 ohms plus or minus 15 percent, though 120-ohm UTP cable is sometimes used in Europe and is allowed by the ISO/IEC 11801 cabling Standard. A typical UTP cable is shown in Figure 1.1. This simple cable consists of a jacket that surrounds four twisted pairs. Each wire is covered by an insulation material with good dielectric properties. For data cables, this means that in addition to being electrically nonconductive, it must also have certain properties that allow good signal propagation. ELECT 122  Twisted-Pair Cable ELECT 122  Twisted-Pair Cable UTP cabling seems to generate the lowest expectations of twisted-pair cable. Its great popularity is mostly due to the cost and ease of installation. With every new generation of UTP cable, network engineers think they have reached the limits of the UTP cable’s bandwidth and capabilities. However, cable manufacturers continue to extend its capabilities. During the development of 10Base-T and a number of pre-10Base-T proprietary UTP Ethernet systems, critics said that UTP would never support data speeds of 10Mbps. Later, the skeptics said that UTP would never support data rates at 100Mbps. In July 1999, the IEEE approved the 1000Base-T standard, which allows Gigabit Ethernet to run over Category 5 cable! ELECT 122  Twisted-Pair Cable Not All UTP Is Created Equal! Though two cables may look identical, their supported data rates can be dramatically different. Older UTP cables that were installed to support telephone systems may not even support 10Base-T Ethernet. The ANSI/TIA/EIA-568-B Standard helps consumers choose the right cable (and components) for the right application. The Standard has been updated over the years and currently defines four categories of UTP cable: Categories 3, 5, 5e, and 6. Note that Category 5 requirements have been moved to an addendum and are not officially recognized as an approved cable for new installations. Here is a brief rundown of Categories past and present: An Ethernet standard that transmits at 10 Mbps over twisted wire pairs (telephone wire). 10Base-T was the first version of Ethernet to use a star architecture. ELECT 122  Twisted-Pair Cable Not All UTP Is Created Equal! Category 1 (not defined by ANSI/TIA/EIA-568-B) This type of cable usually supports frequencies of less than 1MHz. Common applications include analog voice telephone systems. It never existed in any version of the 568 Standard. Category 2 (not defined by ANSI/TIA/EIA-568-B) This cable type supports frequencies of up to 4MHz. It’s not commonly installed, except in installations that use twisted-pair ArcNet and Apple LocalTalk networks. Its requirements are based on the original, proprietary IBM Cabling System. It never existed in any version of the 568 Standard. ELECT 122  Twisted-Pair Cable Not All UTP Is Created Equal! Category 3 (recognized cable type in ANSI/TIA/EIA-568-B) This type of cable supports data rates up to 16MHz. This cable was the most common variety of UTP for a number of years starting in the late 1980s. Common applications include 4Mbps UTP Token Ring, 10Base-T Ethernet, 100Base-T4, and digital and analog telephone systems. Its inclusion in the 568-B Standard is for voice applications. Category 4 (not defined by ANSI/TIA/EIA-568-B) Cable belonging to Category 4 was designed to support frequencies of up to 20MHz, specifically in response to a need for a UTP solution for 16Mbps Token Ring LANs. It was quickly replaced in the market when Category 5 was developed, as Category 5 gives five times the bandwidth with only a small increment in price. Category 4 was a recognized cable in the 568-A Standard, but it has been dropped ELECT 122 from ANSI/TIA/EIA-568-B.  Twisted-Pair Cable Not All UTP Is Created Equal! Category 5 (included in ANSI/TIA/EIA-568-B for informative purposes only) Category 5 was the most common cable installed, until new installations began to use an enhanced version. It may still be the cable type most in use because it was the cable of choice during the huge infrastructure boom of the 1990s. It was designed to support frequencies of up to 100MHz. Applications include 100Base-TX, PMD (FDDI over copper), 155Mbps ATM over UTP, and thanks to sophisticated encoding techniques, 1000Base-T Ethernet. To support 1000Base-T applications, the installed cabling system had to pass performance tests specified by TSB-95 (TSB- 95 was a Technical Service Bulletin issued in support of ANSI/TIA/EIA-568- A, which defines additional test parameters. It is no longer a recognized cable type per the ANSI/TIA/EIA-568-B Standard, but for historical reference purposes, Category 5 requirements, including those taken from TSB-95, are specified in Appendix D of 568-B.1 and Appendix N of 568-B.2. ELECT 122  Twisted-Pair Cable Not All UTP Is Created Equal! Category 5e (recognized cable type in ANSI/TIA/EIA-568-B) Category 5e (enhanced Category 5) was introduced with the TIA/EIA- 568-A-5 addendum of the cabling Standard. Even though it has the same rated bandwidth as Category 5, i.e., 100MHz, additional performance criteria and a tighter transmission test requirement make it more suitable for high-speed applications such as Gigabit Ethernet. Applications are the same as those for Category 5 cabling. It is now the minimum recognized cable category for data transmission in ANSI/TIA/EIA-568-B. ELECT 122  Twisted-Pair Cable Not All UTP Is Created Equal! Category 6 (recognized cable type in ANSI/TIA/EIA-568-B) Category 6 cabling was officially recognized with the publication of an addition to ANSI/TIA/EIA-568-B in June 2002. In addition to more stringent performance requirements as compared to Category 5e, it extends the usable bandwidth to 200MHz. Its intended use is for Gigabit Ethernet and other future high-speed transmission rates. Successful application of Category 6 cabling requires closely matched components in all parts of the transmission channel, i.e., patch cords, connectors, and cable. ELECT 122  Twisted-Pair Cable ELECT 122  Twisted-Pair Cable Some STP cabling, such as IBM Types 1 and 1A cable, uses a woven copper-braided shield, which provides considerable protection against electromagnetic interference (EMI.) Inside the woven copper shield, STP consists of twisted pairs of wire (usually two pairs) wrapped in a foil shield. Some STP cables have only the foil shield around the wire pairs. Figure 1.2 shows a typical STP cable. In the IBM design, the wire used in STP cable is 22 AWG (just a little larger than the 24 AWG wire used by typical UTP LAN cables) and has a nominal impedance of 150 ohms. ELECT 122  Twisted-Pair Cable Simply installing STP cabling does not guarantee you will improve a cable’s immunity to EMI or reduce the emissions from the cable. Several critical conditions must be met to achieve good shield performance: The shield must be electrically continuous along the whole link. All components in the link must be shielded. No UTP patch cords can be used. The shield must fully enclose the pair, and the overall shield must fully enclose the core. Any gap in the shield covering is a source of EMI leakage. The shield must be grounded at both ends of the link, and the building grounding system must conform to grounding standards (such as TIA/EIA-607). ELECT 122  Twisted-Pair Cable Screened Twisted Pair (ScTP) A recognized cable type in the ANSI/TIA/EIA-568-B Standard is screened twisted-pair (ScTP) cabling, a hybrid of STP and UTP cable. ScTP cable contains four pairs of 24 AWG, 100-ohm wire (see Figure 1.3) surrounded by a foil shield or wrapper and a drain wire for bonding purposes. ScTP is also sometimes called foil twisted-pair (FTP) cable because the foil shield surrounds all four conductors. This foil shield is not as large as the woven copperbraided jacket used by some STP cabling systems, such as IBM Types 1 and 1A. ScTP cable is essentially STP cabling that does not shield the individual pairs; the shield may also be smaller than some varieties of STP cabling. ELECT 122  Twisted-Pair Cable Optical-Fiber Cable As late as 1993, it seemed that in order to move toward the future of desktop computing, businesses would have to install fiber-optic cabling directly to the desktop. Copper cable (UTP) performance continues to be surprising, however. Although for most of us fiber to the desktop is not yet a practical reality, fiber-optic cable is touted as the ultimate answer to all our voice, video, and data transmission needs and continues to make inroads in the LAN market. Some distinct advantages of fiber-optic cable include: Transmission distances can be much greater than with copper cable. Potential bandwidth is dramatically higher than with copper. Fiber optic is not susceptible to outside EMI or crosstalk interference, nor does it generate EMI or crosstalk. Fiber-optic cable is much more secure than copper cable because it is extremely difficult to monitor, “eavesdrop,” or tap a fiber cable. Fiber-optic cable can easily handle data at speeds above 1Gbps; in fact, it ELECT 122 has been demonstrated to handle data rates exceeding 200Gbps!  Twisted-Pair Cable Fiber Optic Cabling Comes of Age Affordably Fiber-optic cable used to be much harder to install than copper cable, requiring precise installation practices. However, in the past few years, the cost of an installed fiber-optic link (just the cable and connectors) has dropped and is now often only 10 to 15 percent more than the cost of a UTP link. Better fiber-optic connectors and installation techniques have made fiber-optic systems easier to install. In fact, some installers who are experienced with both fiber- optic systems and copper systems will tell you that with the newest fiber-optic connectors and installation techniques, fiber-optic cable is easier to install than UTP. The main hindrance to using fiber optics all the way to the desktop in lieu of UTP or ScTP is that the electronics (workstation network-interface cards and hubs) are still significantly more expensive, and the total cost of a full to-the-desktop FO installation is ELECT 122 estimated at 50 percent greater than UTP.  Twisted-Pair Cable FIGURE 1.4 A dual fiber-optic cable ELECT 122