Guide to Networking Essentials, Eighth Edition 3-1
Chapter 3
Network Topologies and Technologies
At a Glance
Instructor’s Manual Table of Contents
• Overview
• Objectives
• Teaching Tips
• Quick Quizzes
• Class Discussion Topics
• Additional Projects
• Additional Resources
• Key Terms
• Technical Notes for Hands-On Projects
• Using Virtualization for Hands-On Projects
Guide to Networking Essentials, Eighth Edition 3-2
Lecture Notes
Overview
Chapter 3 offers an introduction to the basic primary physical networking topologies in
common use. Students also learn about the primary logical networking topologies. They
will be able to describe the major LAN networking technologies found in many
networks today. Finally, they will learn about 802.11 Wi-Fi standards and methods.
Objectives
• Describe the primary physical networking topologies in common use
• Describe the primary logical networking topologies in common use
• Describe major LAN networking technologies
• Compare Wi-Fi standards
Teaching Tips
Physical Topologies
1. Emphasize that a physical topology is different from a logical topology, where the
layout of a network could appear completely different.
Physical Bus Topology
1. Describe the limits of a physical bus topology and how these limits contributed to it
becoming a legacy technology.
a. Limit of 30 computers per cable segment
b. Maximum cable length is 185 meters
2. It is worth mentioning that although this technology is now legacy, the Ethernet
standards were born on the physical bus topology.
3. Students should be told the methods by which signals were passed between machines,
Physical Star Topology
1. Discuss the use of a central device for connecting machines on a network using the
physical star topology.
2. Compare the advantages of a physical star topology to the disadvantages of older legacy
topologies.
3. Point out that the details of how data travels from computer to computer in a physical
star depend on the type of central device.
4. Students should learn that the most commonly used network topology is now the
extended star. Use Figure 3-3 in your discussion along with the following points:
5. In contrast to those benefits, be sure to make note that this also creates a central point of
failure. While easy to troubleshoot, sometimes having a single point of failure is too big
of a risk.
Teaching
Tip
Physical cabling has come a long way from what was used on some of these
legacy topologies. Students may find some Thicknet information on
https://www.sqa.org.uk/e-learning/NetTechDC01CCD/page_12.htm.
Physical Ring Topology
1. Explain that a physical ring topology is similar to a bus in cabling structure. Use
Figure 3-4 in your explanation of how a physical ring topology works.
2. Because of their similarities, physical ring also suffers some of the same
Point-to-Point Topology
1. Describe the point-to-point topology and where it is most prevalent: WANs.
Teaching
Tip
For a simplified look at some of these topologies, point your students to
https://www.link-labs.com/blog/iot-topology .
3. Explain that point-to-multipoint (PMP) topology is an arrangement in which a central
4. Mention that this type of topology is most often used in WANs where a main office has
connections to several branch offices via a router.
5. Discuss the use of mesh topology as a means of redundancy and fault tolerance.
Quick Quiz 1
1. What is the difference between physical topology and logical topology?
2. True or False: Any break in a physical star topology causes the entire network to go
down.
3. The physical star topology uses which of the following to interconnect computers in a
LAN?
1. Central device
3. Access point
4. FDDI backbone
Guide to Networking Essentials, Eighth Edition 3-5
4. What is the name of the most widely used physical topology in networks today?
5. How many links would you need in a full mesh configuration if you had 4 nodes?
a. 4
c. 6
d. 7
Logical Topologies
2. Focus on the idea that the logical topology, while partially determined by physical
topology, may not be similar to the physical topology itself. Mention the following for
students:
a. For example, there are physical star topologies that act as a bus logically, such
as a star topology that makes use of a hub.
b. Physical star topologies can also have a logical ring topology when using a
Teaching
Tip
For more information on Physical and Logical Topologies, have students visit:
https://study.com/academy/lesson/physical-logical-topology-definition-
characteristics.html
Network Technologies
1. Discuss with students what network technology is, namely how it applies to what data
link layer protocols are in use.
Network Technologies and Media
1. Show students a strand of unshielded twisted-pair (UTP) cable. While showing the
2. Next, show students some fiber-optic cabling if available to contrast the size difference.
Students should learn where fiber is most commonly used.
3. When discussing coaxial cable, make mention that this is most commonly used for
4. Explain to students the difference between baseband and broadband, and give an
example of which network technologies use either method of signal transmission.
Ethernet Networks
2. Explain that despite how the speed of the interface may change, the underlying Ethernet
Ethernet Addressing
1. Review some of the information discussed in Chapter 2 about MAC addressing: why
Ethernet Frames
1. Discuss some of the different kinds of frame types, and then explain that frame type has
no effect on the attributes of a frame.
2. Students should know the size of a frame can vary between 64 bytes and 1518 bytes.
Discuss the common frame headers and fields.
Ethernet Media Access
2. Explain how the network responds to collisions with CSMA/CD and how the method
Guide to Networking Essentials, Eighth Edition 3-7
Collisions and Collision Domains
1. Emphasize that collisions are only possible when Ethernet is used on shared media.
a. Explain that although a switch will eliminate collisions on segments it is connected
b. Briefly mention that a collision on a switch is technically possible, but only under
Ethernet Error Handling
1. Discuss Ethernet’s best effort delivery system.
a. Students should understand that reliable delivery is left to higher-level protocols to
ensure.
b. Make students aware that while 1-a means Ethernet makes no effort to retransmit a
Half-Duplex Versus Full-Duplex Communication
1. Describe how half-duplex communication compares to full-duplex.
Ethernet Standards
1. Explain the two methods for expressing Ethernet standards.
2. Describe the different Ethernet standards, giving a small amount of time to the legacy
standards so that students are aware of Ethernet’s history.
3. Describe how different standards utilize the same media in different ways. For
example, 100BaseT Ethernet dedicates wire pairs to sending and receiving. 1000BaseT
Ethernet on the other hand uses all wires for sending and receiving simultaneously.
802.11 Wi-Fi
1. With the surge in popularity of mobile devices, discuss the importance of providing a
Wi-Fi Modes of Operation
1. Students should be made aware of the differences between infrastructure mode and ad
hoc mode.
Wi-Fi Channels and Frequencies
1. Illustrate how wireless divides an allocated spectrum into various channels and how
communication occurs on these channels.
Wi-Fi Antennas
2. Discuss the characteristics of the following Wi-Fi antennas, mentioning that antennas
are usually categorized by their radiation pattern:
Wi-Fi Access Methods and Operation
1. Explain that wireless networks use the CSMA/CA (Collision Avoidance) access
2. Review the use of RTS/CTS packets to control wireless device access to media.
3. Point out that while wireless standards specify a possible transmission rate, this value
Guide to Networking Essentials, Eighth Edition 3-10
Wi-Fi Signal Characteristics
1. Explain some common types of signal interference caused by physical objects lying the
path between the transmitter and receiver:
2. Discuss the importance of the signal-to-noise ratio. Point out that there is no escaping
3. Define throughput as the actual amount of data transferred, not counting error and
Wi-Fi Standards
1. Use Table 3-4 to discuss the current Wi-Fi standards available today. Be sure to
Wi-Fi Security
1. Discuss the importance of securing access to a Wi-Fi network. Point out that Wi-Fi
Token Ring Networks
1. Discuss the 802.5 token ring standard.
a. What media is required for token ring?
b. Maximum transmission speeds for token ring?
Fiber Distributed Data Interface Technology
1. Describe the dual-ring FDDI technology.
a. Despite the limitations of using ring technology, FDDI accomplished 100 Mbps
speeds.
Guide to Networking Essentials, Eighth Edition 3-11
Quick Quiz 3
1. What is the networking standard for wireless networking (also known as Wireless
Fidelity or Wi-Fi)?
2. Which Wi-Fi mode of operation is typically used in small or temporary installations,
where data travels from one device to another in a line?
3. In which type of Wi-Fi antenna do signals radiate out from the antenna with equal
strength in all directions?
4. At what speed did token ring originally operate?
5. Which media access method is used by FDDI?
Class Discussion Topics
1. Have students discuss why the star topology ultimately won out over other LAN
Additional Projects
1. Have students take a look at some of the older legacy Ethernet technologies, and discuss
how things have changed in the time since these technologies. Compare how old
Additional Resources
1. Star Topology: Advantages and Disadvantages
2. How Fiber Optics Work
3. Collision Domain Tutorial:
4. How Ethernet Works
5. Wi-Fi 802.11ax
Key Terms
For explanations of key terms, see the Glossary for this text.
➢ Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
➢ Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
➢ collision
➢ collision domain
➢ Cyclic Redundancy Check (CRC)
➢ multiuser MIMO (MU-MIMO)
➢ network backbone
➢ omnidirectional antenna
➢ overhead
Guide to Networking Essentials, Eighth Edition 3-13
➢ throughput
➢ token ring
➢ unidirectional antenna
➢ wireless bridge
➢ Wireless Fidelity (Wi-Fi)
Technical Notes for Hands-On Projects