39 - 238 CCNA 2: Routers and Routing Basics v3.1 Instructor Guide – Module 4 Copyright © 2004, Cisco Systems, Inc.
Module 4: Learning about Other Devices Overview
Module 4 will introduce students to the Cisco Discovery Protocol (CDP). CDP is enabled by
default on all Cisco devices. CDP allows devices such as Cisco routers to obtain information
about directly connected routers, switches, and bridges. CDP functions at Layer 2 in the OSI
model. It operates independently of Layer 3, which means that devices can gather information
about other directly connected devices regardless of network layer protocol issues.
The first lesson will explain how CDP is used to acquire information about neighboring routers.
Students should already know how use serial and Ethernet connections to physically connect
routers. Students should also know how to use programs such as HyperTerminal and Telnet to
perform router configuration tasks. Review these skills if necessary. Have students perform a
standard lab-setup configuration as an optional skill review.
The second lesson will introduce students to the TCP/IP protocol Telnet. Telnet is a remote
connection utility that allows network administrators to perform configuration and management
tasks on routers and switches. Students will learn how to establish, manage, and terminate
Telnet sessions with remote devices. Students should already be familiar with basic router
setup and configuration. Students should possess basic router configuration skills and be able
to physically connect the devices. Students will use embedded Layer 3 through Layer 7
protocols to establish, test, suspend, or disconnect connectivity to remote devices from the
router console.
Module 4 Caution
Most students do not understand that CDP and Telnet are powerful troubleshooting tools. At
this point, it is important to provide additional support for students who have not mastered
Module 3. Cover this module extensively. Many of the next modules are lab intensive and time
intensive.
Students who complete this module should be able to perform the following tasks:
• Enable and disable CDP
• Use the show cdp neighbors command
• Determine which neighboring devices are connected to which local interfaces
• Use CDP to gather network address information about neighboring devices
• Establish a Telnet connection
• Verify a Telnet connection
• Disconnect from a Telnet session
• Suspend a Telnet session
• Perform alternative connectivity tests