Part I: LAN Switching

Chapter 1 LAN Switching Review and Configuring Cisco 2950 LAN Switches

Chapter 2 Spanning Tree Protocol

Chapter 3 Virtual LANs and Trunking

This chapter covers the following subjects:

■Brief Review of LAN Switching

■Basic Configuration and Operation Commands for the Cisco 2950 Switch

C H A P T E R 1

LAN Switching Review and

Configuring Cisco 2950 LAN Switches

This chapter covers two different major topics. It starts with some basics about how LAN switches work. The second, and by far larger, part of this chapter covers some basic LAN switch configuration on the Cisco 2950 switch.

If you are planning on taking the two-exam approach to CCNA, and you are reading this book, you should already have passed the INTRO exam, and you are beginning to study for the ICND exam. The first part of this chapter, which reviews LAN basics, reminds you of a few details you should already know pretty well. Depending on how much you remember about LAN switching and Ethernet addresses, you might want to skip this first section.

If you’re taking the one-exam approach to CCNA, if you’re following the reading plan described in the Introduction to this book, you already have LAN switching concepts firmly in mind from Chapter 9, “Cisco LAN Switching Basics”, of the CCNA INTRO Exam Certification Guide. So you too can skip this first section as well.

If you want a brief review of LAN switching concepts, definitely take a few minutes to read over the first section of this chapter.

“Do I Know This Already?” Quiz

The purpose of the “Do I Know This Already?” quiz is to help you decide if you need to read the entire chapter. If you intend to read the entire chapter, you do not necessarily need to answer these questions now.

The 12-question quiz, derived from the major sections in the “Foundation Topics“ section, helps you determine how to spend your limited study time.

6 Chapter 1: LAN Switching Review and Configuring Cisco 2950 LAN Switches

Table 1-1 outlines the major topics discussed in this chapter and the “Do I Know This Already?” quiz questions that correspond to those topics.

Table 1-1 “Do I Know This Already?” Foundation Topics Section-to-Question Mapping

CAUTION The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you don’t know the answer to a question or you’re only partially sure of the answer, you should mark this question as wrong for purposes of the self-assessment. Giving yourself credit for an answer you guess correctly skews your self-assessment results and might give you a false sense of security.

1.Which of the following statements describes part of the process of how a switch decides to forward a frame destined for a unicast MAC address?

a.It compares the unicast destination address to the bridging, or MAC address, table.

b.It compares the unicast source address to the bridging, or MAC address, table.

c.It forwards out all interfaces, except the incoming interface, every time.

d.It forwards based on the VLAN ID.

e.It compares the destination IP address to the destination MAC address.

f.It compares the frame’s incoming interface to the source MAC entry in the MAC address table.

2.Which of the following statements describes part of the process of how a LAN switch decides to forward a frame destined for a broadcast MAC address?

a.It compares the unicast destination address to the bridging, or MAC address, table.

b.It compares the unicast source address to the bridging, or MAC address, table.

c.It forwards out all interfaces, except the incoming interface, every time.

d.It forwards based on the VLAN ID.

e.It compares the destination IP address to the destination MAC address.

f.It compares the frame’s incoming interface to the source MAC entry in the MAC address table.

“Do I Know This Already?” Quiz 7

3.Which of the following statements best describes what a switch does with a frame destined for an unknown unicast address?

a.It forwards out all interfaces except the incoming interface.

b.It forwards based on the VLAN ID.

c.It compares the destination IP address to the destination MAC address.

d.It compares the frame’s incoming interface to the source MAC entry in the MAC address table.

4.Which of the following comparisons does a switch make when deciding whether to add a new MAC address to its bridging table?

a.It compares the unicast destination address to the bridging, or MAC address, table.

b.It compares the unicast source address to the bridging, or MAC address, table.

c.It compares the VLAN ID and source MAC address to the bridging, or MAC address, table.

d.It compares the destination IP address’s ARP cache entry to the bridging, or MAC address, table.

5.In which of the following CLI modes could you configure the duplex setting for interface fastethernet 0/5?

a.User mode

b.Enable mode

c.Global configuration mode

d.Setup mode

e.Interface configuration mode

6.In which of the following CLI modes could you issue a command to erase the switch’s initial configuration?

a.User mode

b.Enable mode

c.Setup mode

d.Global configuration mode

e.Interface configuration mode

8Chapter 1: LAN Switching Review and Configuring Cisco 2950 LAN Switches

7.What type of switch memory is used to store the configuration used by the switch when the switch first comes up?

a.RAM

b.ROM

c.Flash

d.NVRAM

e.Bubble

8.What command copies the configuration from RAM into NVRAM?

a.copy running-config tftp

b.copy tftp running-config

c.copy running-config start-up-config

d.copy start-up-config running-config

e.copy startup-config running-config

f.copy running-config startup-config

9.You configure the enable secret command, followed by the enable password command, from the console. You log out of the switch and log back in at the console. Which command defines the password you had to enter to access privileged mode again from the console?

a.enable password

b.enable secret

c.Neither enable password nor enable secret

d.You cannot configure both the enable secret password and the enable password at the same time.

10.What command is used on a switch to set the switch’s IP address for in-band management to 10.1.1.1, subnet mask 255.255.255.0?

a.ip address 10.1.1.1 255.255.255.0

b.ip address 10.1.1.1 mask 255.255.255.0

c.address 10.1.1.1 255.255.255.0

d.set ip address 10.1.1.1 255.255.255.0

e.set ip address 10.1.1.1 mask 255.255.255.0

“Do I Know This Already?” Quiz 9

11.Imagine a 2950 switch with a PC plugged into interface fastethernet 0/1 and a router plugged into interface fastethernet 0/2. The PC needs to use TCP/IP to communicate through the router with other TCP/IP hosts. In what configuration mode could you enter the switch’s IP address?

a.User mode

b.Enable mode

c.Setup mode

d.Global configuration mode

e.Interface configuration mode for fastethernet 0/1

f.Interface configuration mode for fastethernet 0/2

g.None of the above

12.What interface subcommand tells the switch to take an interface out of service?

a.down

b.admin down

c.shutdown

d.admin shutdown

e.disable

The answers to the “Do I Know This Already?” quiz appear in Appendix A. The suggested choices for your next step are as follows:

■10 or less overall score—Read the entire chapter. This includes the “Foundation Topics,“ “Foundation Summary,” and “Q&A” sections.

■11 or 12 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.