Networking Chapter 9 Ccna Guide Cisco Networking Fundamentals Fourth Edition Addressing Glance Instructors Manual

CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 4-1

Chapter 4

IP Addressing

At a Glance

Instructor’s Manual Table of Contents

• Overview

• Objectives

• Teaching Tips

• Quick Quizzes

• Class Discussion Topics

• Additional Projects

• Additional Resources

• Key Terms

CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 4-2

Lecture Notes

Overview

Chapter 4 reviews IP addressing. Students will learn the different classes of IP addresses.

Next, students will see how to configure IP addresses and subdivide an IP network. In

addition, Chapter 4 discusses advanced routing concepts such as CIDR, summarization, and

VLSM. Students will also learn how to convert between decimal, binary, and hexadecimal

numbering systems. Finally, Chapter 4 explains the differences between IPv4 and IPv6.

Chapter Objectives

• Explain the different classes of IP addresses

• Configure IP addresses

• Subdivide an IP network

• Discuss advanced routing concepts such as CIDR, summarization, and VLSM

• Convert between decimal, binary, and hexadecimal numbering systems

• Explain the differences between IPv4 and IPv6

Teaching Tips

IP Addressing

192.168.1.1.

3. Use Table 4-1 to describe how to convert from binary digits to a decimal number.

MAC to IP Address Comparison

2. Mention that network devices could not efficiently route traffic on a large internetwork

3. Explain that IP addressing was devised for use on large networks. IP addresses have a

CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 4-3

Teaching

Tip

If the Internet used MAC addresses, huge tables would have to be maintained

containing not only the MAC addresses of each and every computer, but also

each device along the path to that computer.

IP Classes

1. Explain that the Internet Assigned Numbers Authority (IANA) devised the hierarchical

IP addressing structure. The American Registry of Internet Numbers (ARIN) manages

2. Explain that Class A addresses are reserved for governments and large corporations

3. Mention that Class B addresses are assigned to large- and medium-sized companies.

4. Explain that Class C addresses are assigned to groups that do not meet the qualifications

to obtain Class A or B addresses. Each Class C address supports 254 hosts. Use Figure

5. Explain that Class D addresses (also known as multicast addresses) are reserved for

6. Mention that Class E addresses are reserved for research, testing, and experimentation.

7. Mention that many companies use private IP addresses for their internal networks. They

will not be routable on the Internet. Use Table 4-2 to show the private IP ranges.

Teaching

Tip

Refer your students to http://www.howstuffworks.com/question549.htm for

additional information about IP addresses.

Network Addressing

2. Explain that a subnet mask indicates how much of the IP address represents the network

or subnet. Standard (default) subnet masks include the following:

3. Explain that TCP/IP hosts use the combination of the IP address and the subnet mask to

4. Define subnetting as the manipulation of the subnet mask to get more network numbers.

5. Explain that when the entire host portion of an IP address is all binary ones, the address

Broadcast Types

1. Define flooded broadcasts as broadcasts for any subnet. They use the IP address

2. Explain that directed broadcasts are for a specific subnet. Routers can forward directed

Subdividing IP Classes

1. Describe some of the reasons for subnetting, including:

a. To match the physical layout of the organization

2. Use Figure 4-9 to describe how to divide a Class B network.

Subnet Masking

1. Explain that when network administrators create subnets, they borrow bits from the

2. Mention that Class C addresses also can be subdivided, but not as many options or

3. Use Figure 4-10 to illustrate the possible binary combinations that can be used as subnet

masks.

Teaching

Tip

The subnet masks have a clear binary pattern. They must have a continuous

string of ones from the left side of the octet.

Quick Quiz 1

1. The ____ manages IP addresses in the United States.

2. The ____ is a global, government-independent entity with overall responsibility for the

Internet.

3. It seems that 127.0.0.1 (decimal) is the highest assignable Class A address, but that

particular address range is reserved as the ____ address.

4. ____ is the sending of a stream of data (usually audio and video) to multiple computers

Learning to Subnet

1. Use Figures 4-11 and 4-12 and Table 4-5 to describe how to subnet a Class C network

2. Mention that only one subnet mask can handle your network configuration:

255.255.255.224. This subnet mask will allow you to create eight subnetworks and to

Subnetting Formulas

1. Explain the following two formulas:

CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 4-6

b. 2x – 2 = # of usable hosts per subnet (where x is the number of bits remaining in

the host field after borrowing)

Teaching

Tip

Most router internetworking operating systems (IOS) in use today support the

use of the first and last subnet. This is referred to as “supporting subnet zero.” If

you are using an older IOS, you must subtract 2 when calculating the number of

usable subnets.

2. Use Figures 4-13 and 4-14 to show an example of how to use these two formulas.

CIDR

1. Explain that Classless Inter-Domain Routing (CIDR) was developed to slow the

2. Mention that the CIDR addressing method allows the use of a prefix to designate the

3. Mention that the prefix can be longer than the default subnet mask (subnetting) or it can

be shorter than the default mask (supernetting).

Teaching

Tip

The allocation of network numbers based on CIDR has helped slow the depletion

of addresses. CIDR is now used by all backbone routers and most ISPs.

Summarization

1. Explain that summarization, also known as route aggregation or supernetting, allows

2. Explain that to summarize a group of subnets, you must count the number of bits that

Variable Length Subnet Masks

2. Mention that basic routing protocols such as RIP version 1 and IGRP do not support

3. Mention that RIP version 2, OSPF, or EIGRP are classless protocols. In a classless

4. Use Figure 4-15 and Tables 4-7 and 4-8 to show a real example of how to use VLSM.

Working with Hexadecimal Numbers

1. Explain that the hexadecimal numbering system is base 16; it means 16 numerals are

2. Mention that often you will come across hexadecimal numbers when working with

3. Use Table 4-9 to explain how to convert decimal numbers to hexadecimal numbers.

IPv4 versus IPv6

1. Explain that IP version 4 (IPv4) is the version of IP currently deployed on most systems

2. Mention that CIDR has slowed the exhaustion of IPv4 address space and made the

3. Define Network Address Translation (NAT) as a technique developed in part to slow

4. Mention that NAT is CPU intensive and expensive, and some protocols do not work

well with NAT, such as the IP Security Protocol (IPSec).

6. Explain that IPv4 networks rely on broadcasting. Broadcasting is inefficient because

7. Mention that IPv6 addresses are 128 bits compared with IPv4’s 32-bit structure. IPv6

8. Explain that IPv6 can be subnetted. CIDR notation is also used with IPv6, for example,

Transitioning to IPv6

1. Explain that dual stack involves enabling IPv6 on all routers, switches, and end nodes

but not disabling IPv4. Both version 4 and version 6 stacks run at the same time.

2. Explain that tunneling encapsulates IPv6 traffic inside IPv4 packets. This is done when

portions of a network are running IPv6 and other network areas have not been upgraded

yet. The greatest concern with tunneling involves security.

Quick Quiz 2

1. True or False: A Class C address only allows the administrator to subnet the last octet.

2. ____ is also known as route aggregation. It is also sometimes called supernetting.

3. The ____ numbering system is base 16; in other words, 16 numerals are used to express

any given number.

4. ____ is a transition method that encapsulates IPv6 traffic inside IPv4 packets.

Class Discussion Topics

1. What are the benefits of subnetting and supernetting?

2. Is NAT the same as subnetting?

Additional Projects

1. Answer the following questions:

i. What is the subnet address for the host with the IP address 55.55.73.151/24?

ii. What is the subnet mask for the host with the IP address 55.55.73.151/24?

mask 255.255.248.0?

CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 4-9

iv. How many IP addresses are there for each subnet if you apply the subnet mask

255.255.248.0 to a Class B IP address?

2. Ask your students to divide the network 160.238.0.0 into 50 subnets and answer the

following questions:

i. What is the subnet mask to use?

ii. What is the first address that you can assign to a host in the first subnet? (Do not

consider the subnet zero.)

iii. How many hosts can you have in each subnet?

Additional Resources

htm

4. IP subnetting made easy

5. Classless Inter-Domain Routing

Key Terms

➢ American Registry of Internet Numbers (ARIN) An organization that manages IP

255.255.255.255. Routers do not pass flooded broadcasts.

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➢ hexadecimal A base 16 numbering system that uses numerals 0 through 9 and the

letters A through F to represent numbers. MAC addresses and IPv6 addresses are

displayed in hexadecimal.

➢ IPv6 The newest version of IP addressing that involves 128-bit addresses expressed as

hexadecimal numbers.

➢ loopback The TCP/IP Class A address 127.x.x.x that is reserved for diagnostic

purposes. Any address on this network allows you to check if TCP/IP has been properly

installed on the system. (Specifically, the IP address 127.0.0.1 is the address usually

➢ prefix A way of designating the subnet mask that involves a forward slash followed by

the number of binary ones in the mask; in other words, the network portion.

➢ subnet A portion of a network that has been separated from the main network by using

a different subnet mask.

➢ subnet mask A required component for all IP hosts used in combination with an IP