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C H A P T E R11
LAN Cabling, Standards, and Topologies
This chapter completes the Ethernet puzzle for this book, in relation to the requirements of the INTRO exam. Ethernet was covered in several other chapters of this book— specifically, Chapter 3, “Data Link Layer Fundamentals: Ethernet LANs,” Chapter 9, “Cisco LAN Switching Basics,” and Chapter 10, “Virtual LANs and Trunking.” The topics in those chapters laid the foundation of a relatively broad knowledge of Ethernet. However, to keep those chapters flowing and not get bogged down in some long tangents (in some cases, relatively unimportant tangents), those earlier chapters did not cover all the details of Ethernet that might be on the INTRO exam.
For those of you studying for the CCNA exam—in other words, the single-exam method of getting your CCNA certification—you are probably following the reading plan outlined in the introduction. For you, after this chapter, you should move on to the first three chapters of CCNA ICND Exam Certification Guide.
AUTHOR’S NOTE While they may be on the CCNA exam, the topics in this chapter are less likely to be on the CCNA exam than most other topics in this book. For those of you that are planning to take the CCNA exam, instead of taking both the INTRO and ICND exams, you might consider skipping this chapter. Refer to the introduction to this book for more perspectives on the CCNA exam topics.
“Do I Know This Already?” Quiz
The purpose of the “Do I Know This Already?” quiz is to help you decide whether you really need to read the entire chapter. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now.
The eight-question quiz, derived from the major sections in “Foundation Topics” portion of the chapter, helps you determine how to spend your limited study time.
280 Chapter 11: LAN Cabling, Standards, and Topologies
Table 11-1 outlines the major topics discussed in this chapter and the “Do I Know This Already?” quiz questions that correspond to those topics.
Table 11-1 “Do I Know This Already?” Foundation Topics Section-to-Question Mapping
Foundations Topics Section
Network Topologies
Cabling and Connectors
Ethernet Standards
Wireless Communications
Questions Covered in This Section
1–2
3–5
6–7
8
CAUTION The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you do not know the answer to a question or are only partially sure of the answer, you should mark this question wrong for purposes of the self-assessment. Giving yourself credit for an answer that you correctly guess skews your self-assessment results and might provide you with a false sense of security.
1. Which of the following network topologies is characterized by attachments from many devices to a single linear cable?
a. Bus b. Star
c. Extended star d. Full mesh
e. Partial mesh
2. Which of the following types of networks is considered to be a logical bus topology?
a. 10BASE5
b. PCs connected to a hub using 10BASE-T
c. PCs connected to a switch using 10BASE-T
d. Five routers, each with a PVC connecting it to all the others, over Frame Relay
3. Which pins typically are used on an RJ-45 connector by an Ethernet card to support Fast Ethernet over UTP cabling?
a. 1, 2, 3, 4 b. 1, 2, 4, 5 c. 1, 2, 3, 6
“Do I Know This Already?” Quiz 281
d. 1, 2, 7, 8 e. 5, 6, 7, 8
4. Which part of an optical cable reflects the light back into the cable as a result of a different refractive index?
a. Cladding b. Core
c. Jacket
d. Plastic shield e. Kevlar shield
5. Which of the following UTP cable types support Gigabit Ethernet?
a. CAT3 b. CAT4 c. CAT5 d. CAT5E e. CAT6
6. Which of the following Ethernet standards call for the use of 802.3 MAC and 802.2 LLC standards?
a. 802.3u b. 802.3z c. 802.3ab d. 802.3ae
e. All of the above
7. Which of the following Ethernet standards refer to Gigabit Ethernet?
a. 802.3u b. 802.3z c. 802.3ab d. 802.3ae
e. All of the above
282 Chapter 11: LAN Cabling, Standards, and Topologies
8. Which of the following IEEE standards define framing used when transmitting wireless LAN traffic?
a. IEEE 802.2 b. IEEE 802.3 c. IEEE 802.1d d. IEEE 802.11
e. None of the above
The answers to the “Do I Know This Already?” quiz are found in Appendix A, “Answers to the ‘Do I Know This Already?’ Quizzes and Q&A Sections.” The suggested choices for your next step are as follows:
6 or less overall score—Read the entire chapter. This includes the “Foundation Topics” and “Foundation Summary” sections and the Q&A section.
7 or 8 overall score—If you want more review on these topics, skip to the “Foundation Summary” section and then go to the Q&A section. Otherwise, move to the next chapter.
Network Topologies 283
Foundation Topics
This chapter begins with a description of different topologies that you might find in different types of networks, including Ethernets, but also including other types of networks. Next, Ethernet standards and cabling options are detailed. Finally, the chapter closes with a brief description of wireless technology and wireless LANs.
Network Topologies
You already have been introduced to several different network topologies as you have read through this book. For instance, 10BASE2 networks use a physical bus topology, whereas 10BASE-T networks use a physical star topology. This section introduces you to several other types of network topologies.
Figure 11-1 shows the different types of Ethernet topologies covered earlier in the book, with some specific terms used to describe the topology for each design.
Figure 11-1 Different Types of Network Topologies for Ethernet So Far in This Book
Hub1 Switch1
¥ Physical Bus ¥ Logical Bus
¥ Physical Star ¥ Logical Bus
¥ Physical Star ¥ Logical Star
The figure shows a 10BASE5 network, a 10BASE-T network using a shared hub, and a switch with 10/100 links. Physically, the topologies with the hub and the switch look a little like how a child might draw a star, or the sun, with a center (the hub or switch) and with beams of light pointing outward (like the Ethernet cables to the PCs in the figure). Star topologies also are called hub-and-spoke topologies.
Physical bus topologies transmit the electrical signal from one end of a cable to the other, with the signal being picked up at each connection point.
The term logical topology refers to how the network behaves. For instance, from Chapter 3, you know that a 10BASE-T hub repeats an incoming signal out every other port on the hub.
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