Cabling

The Complete Guide to Copper and Fiber-Optic Networking

Bill Woodward

• Publisher: Sybex
• Year: 2014
• ISBN:
  9781118807385
• Edition: 5
• Topic: Informatik
• Subtopic: Computernetzwerke

Develop the skills you need to design and build a reliable, cost-effective cabling infrastructure

Fully updated for the growing demand of fiber optics for large-scale communications networks and telecommunication standards, this new edition is organized into two parts. Part I covers LAN Networks and Cabling Systems offers comprehensive coverage on current cabling methodologies and is updated to the latest industry standards. Part II addresses Fiber-Optic Cabling and Components probes deeper into fiber optics, and can be used to prepare for the Fiber Optics Installer (FOI) and/or Fiber Optics Technician (FOT) certifications, two of the Electronic Technician's Association's leading certifications.

• Explains why cutting corners is a bad idea
• Walks you through the obstacles to high-speed data transfer
• Encourages you to follow the golden rules of cabling

This new edition is the only book you need for current cabling methodologies and standards.

Part I

LAN Networks and Cabling Systems

• Chapter 1: Introduction to Data Cabling
• Chapter 2: Cabling Specifications and Standards
• Chapter 3: Choosing the Correct Cabling
• Chapter 4: Cable System and Infrastructure Constraints
• Chapter 5: Cabling System Components
• Chapter 6: Tools of the Trade
• Chapter 7: Copper Cable Media
• Chapter 8: Fiber-Optic Media
• Chapter 9: Wall Plates
• Chapter 10: Connectors
• Chapter 11: Network Equipment
• Chapter 12: Wireless Networks
• Chapter 13: Cabling System Design and Installation
• Chapter 14: Cable Connector Installation
• Chapter 15: Cable System Testing and Troubleshooting
• Chapter 16: Creating a Request for Proposal
• Chapter 17: Cabling @ Work: Experience from the Field

Chapter 1

Introduction to Data Cabling

“Data cabling! It’s just wire. What is there to plan?” the newly promoted programmer-turned-MIS-director commented to Jim. The MIS director had been contracted to help the company move its 750-node network to a new location. During the initial conversation, the director had a few other “insights”:

• He said that the walls were not even up in the new location, so it was too early to be talking about data cabling.
• To save money, he wanted to pull the old Category 3 cabling and move it to the new location. (“We can run 100Base-TX on the old cable.”)
• He said not to worry about the voice cabling and the cabling for the photocopier tracking system; someone else would coordinate that.

Jim shouldn’t have been too surprised by the ridiculous nature of these comments. 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 30 years.

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 professional.

In this chapter, you will learn to:

• Identify the key industry standards necessary to specify, install, and test network cabling
• Understand the different types of unshielded twisted-pair (UTP) cabling
• Understand the different types of shielded twisted-pair cabling
• Determine the uses of plenum- and riser-rated cabling
• Identify the key test parameters for communications cables

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. Using 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!
• 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 5 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.

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 upward 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.

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TIP

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.

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Of course, these were facts that we already knew from our own experiences. We have spent countless hours troubleshooting cabling systems that were nonstandard, badly designed, poorly documented, and shoddily installed. We have seen many dollars wasted on the installation of additional cabling and cabling infrastructure support that should have been part of the original installation.

Regardless of how you look at it, cabling is the foundation of your network. 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 moved into a new datacenter space used the existing cabling, which was supposed to be Category 5e cable. Almost immediately, 10 Gigabit Ethernet network users reported intermittent problems.

These problems included exceptionally slow access times when reading email, saving documents, and using the sales database. Other users reported that applications running under Windows XP and Windows Vista were locking up, which often caused users 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 5e installation, and other cabling runs were installed and terminated poorly.

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NOTE

Often, network managers mistakenly assume that data cabling either works or it does not, with no in-between. Cabling can cause intermittent problems.

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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, cell 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.

Robert Metcalfe (inventor of Ethernet, founder of 3Com, columnist for InfoWorld, and industry pundit) helped coin the term drop-rate magnification. Drop-rate magnification describes the high degree of network problems caused by dropping a few packets. Metcalfe estimates that a 1 percent drop in Ethernet packets can correlate to an 80 percent drop in throughput. Modern network protocols that send multiple packets and expect only a single acknowledgment are especially susceptible to drop-rate magnification, as a single dropped packet may cause an entire stream of packets to be retransmitted.

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 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 w...