Network+ Guide to Networks, 8th Edition 4-1
Chapter 4
Network Protocols and Routing
At a Glance
Instructor’s Manual Table of Contents
• Overview
• Objectives
• Teaching Tips
• Quick Quizzes
• Class Discussion Topics
Network+ Guide to Networks, 8th Edition 4-2
Lecture Notes
Overview
Chapter 4 focuses on how application data and instructions make the trip from one host to
another at the Transport, Network, and Data Link layers. Students will learn how protocol
messages are constructed at each of these layers, and they will explore the basics of how
routers work, primarily at the Network layer. Finally, they will learn how to troubleshoot route
issues between hosts.
Chapter Objectives
After reading this chapter and completing the exercises, the student will be able to:
• Describe the functions of core TCP/IP protocols
• Identify how each protocol’s information is formatted in a TCP/IP message
Teaching Tips
TCP/IP Core Protocols
1. Emphasize that TCP/IP is a suite of specialized protocols and provide examples.
2. Use Figure 4-1 to review what occurs at each layer as data is exchanged between a
browser and a Web server.
TCP (Transmission Control Protocol)
2. Explain characteristics of the Transport layer that affect TCP transmissions:
a. connection-oriented
3. Use Figure 4-3 to illustrate the format of a TCP segment.
4. Explain how the entire segment becomes data portion of an IP message.
5. Use Table 4-1 to describe the fields belonging to the TCP segment.
7. Describe the contents of the three segments (SYN, SYN/ACK, and ACK) transmitted.
UDP (User Datagram Protocol)
2. Mention that UDP’s lack of sophistication makes it more efficient and faster than TCP.
3. Describe a situation that makes UDP useful.
4. Use Figure 4-6 to illustrate the format of a UDP segment.
IP (Internet Protocol)
2. Remind students that at the Network layer of the OSI model, data is formed into
packets. Explain the purpose of the IP packet.
4. Use Figure 4-7 to illustrate the format of an IPv4 packet.
5. Use Table 4-3 to describe the fields in an IPv4 packet.
7. Use Figure 4-9 to illustrate the format of an IPv6 packet, and figure 4-10 to illustrate an
example of an IPv6 packet header.
8. Ensure students understand the length and other structural differences between IPv4 and
IPv6 packets. Uses Tables 4-3 and 4-5 in your discussion.
ICMP (Internet Control Message Protocol)
1. Introduce ICMP (Internet Control Message Protocol) and describe its purpose.
2. Describe the types of errors ICMP may report.
4. Point out that just as there are two version of IP, there are also two versions of ICMP:
ARP (Address Resolution Protocol)
1. Introduce ARP (Address Resolution Protocol) and explain that it is used to maintain a
database that maps local IP addresses to MAC addresses.
3. Use Figure 4-12 to illustrate what an ARP table might look like.
4. Introduce the two types of entries an ARP table can contain:
5. Demonstrate how the ARP utility is accessed and the information the utility provides.
Use Table 4-13 to show the results of using the arp –a command on a Windows
workstation.
Network+ Guide to Networks, 8th Edition 4-5
Ethernet
2. Point out that Ethernet II is the current Ethernet standard. Use Figure 4-14 and Table 4-
8 to discuss the components of a typical Ethernet II frame.
4. Be sure to mention that there are a few notable exceptions to Ethernet frame size
limitations:
a. Ethernet frames on a VLAN can have an extra 4-byte field between Source
Quick Quiz 1
1. At which layer of the OSI model is a packet encapsulated with its own header and
trailer to create a frame?
a. Layer 1
b. Layer 3
c. Layer 4
d. Layer 2
2. TCP (Transmission Control Protocol) operates in which layer of the OSI model?
a. Physical
b. Transport
c. Network
d. Data Link
3. True or False: UDP provides error checking and sequencing.
4. Which Network layer protocol reports on the success or failure of data delivery?
a. ARP
b. UDP
c. ICMP
d. TCP
5. ARP relies on _____, which transmits simultaneously to all nodes on a particular
network segment.
Routers and How They Work
1. Introduce students to the internetworking device known as a router. Explain that a
router joins two or more networks and passes packets from one network to another.
3. Discuss the three various router categories:
4. Use Figure 4-17 to illustrate the three different types of routers.
Multilayer Switches
1. Define a Layer 3 switch as being capable of interpreting Layer 3 data and working
much like a router. Point out the primary difference is the way the hardware is built.
3. Describe the advantages and disadvantages of multilayer switches.
Routing Tables
1. Define and describe a routing table.
3. Use Figure 4-18 and Table 4-9 to describe how routing tables may be used to find the
best path for a message to take in order to reach its destination.
Routing Path Types
1. Describe the two methods of directing network traffic:
a. Static routing
The route Command
1. Explain that the route command allows you to view a host’s routing table. Point out that
Routing Metrics
2. Discuss some examples of routing metrics used by routers:
a. Hop count
b. Theoretical bandwidth
c. Latency
Routing Protocols to Determine Best Paths
1. Define and describe the term best path.
2. Explain that a routing protocol is used to collect data about current network status and
3. Define and describe:
• administrative distance (AD)
4. Use Table 4-10 to summarize some common routing protocols.
Interior and Exterior Gateway Routing Protocols
1. Explain that routing protocols are classified as IGP or EGP. Discuss the differences
2. Introduce distance-vector routing protocols and explain how they work. Point out that
RIP, RIPv2, and EIGRP are distance-vector protocols.
4. Mention that the only EGP currently in use is BGP.
6. Discuss the following characteristics of OSPF:
a. supports large networks
7. Explain how IS-IS (Intermediate System to Intermediate System) works.
9. Point out that originally, EIGRP was proprietary to Cisco routers. While the standard
10. Explain how BGP (Border Gateway Protocol) works. Discuss the following
characteristics:
Troubleshooting Route Issues
1. Point out that TCP/IP comes with a complete set of utilities that can help track down
Troubleshooting Tools
1. Remind students of the TCP/IP utilities they have already covered and introduce the
following tools that can help discover information about a network.
3. Use Table 4-11 to discuss the netstat command options.
4. Define and explain the tracert or traceroute utility.
a. Note that the utility is known as tracert on Windows-based systems and
5. Use Table 4-12 to review traceroute and tracert command options.
7. Point out that a trace cannot detect router configuration problems or predict variations
of routes over a period of time.
9. Use Table 4-13 to review pathping command options.
11. Point out that you must either use the sudo command or log in as root to access
tcpdump.
Network+ Guide to Networks, 8th Edition 4-10
Solving Common Routing Problems
2. Explain that interface errors occur when a logical connection between a node and a
network is malfunctioning.
4. Discuss possible ways to troubleshoot hardware failures.
Quick Quiz 2
1. Which of the following devices joins two or more networks and passes packets from
one network to another?
a. Repeater
b. Web server
c. Router
d. Hub
2. Switches that operate anywhere between Layer 4 and Layer 7 are also known as ____or
application switches.
3. A technique in which a network administrator programs a router to use specific paths
between nodes is known as which of the following?
a. static routing
b. routing protocol
c. dynamic routing
d. default gateway
4. Which of the following routing metrics is a measure of the number of network segments
crossed?
a. latency
b. hop count
c. MTU
d. cost
5. Which of the following routing protocols are used by border routers and exterior routers
to distribute data outside of an autonomous system?
a. BGP
b. RIP
c. OSPF
d. IS–IS
Class Discussion Topics
1. As a class, compare and contrast TCP and UDP.
Additional Projects
1. Have student select five random companies, and issue the tracert or traceroute
1. Have each student research available routers. The report should include a write-up for
three to five devices. Included in the write-up should be a description of the device,
Additional Resources
1. IBM TCP/IP RedBook
3. IPv6
Network+ Guide to Networks, 8th Edition 4-12
4. IPv4 and IPv6 Technical Reference
5. How Routers Work
Key Terms
For definitions of key terms, see the Glossary near the end of the book.
➢ AD (administrative distance)
➢ core router
➢ CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
➢ default route
➢ distance-vector routing protocol
➢ dynamic ARP table entry
➢ IGP (interior gateway protocol)
➢ interior router
➢ internetwork
➢ IS-IS (Intermediate System to Intermediate System)
➢ jumbo frame
➢ latency
➢ pathping
➢ probe
➢ protocol analyzer
➢ RIP (Routing Information Protocol)
➢ RIPv2 (Routing Information Protocol version 2)