Cisco Systems CCNA 2 manual Interface descriptions, Configuring an interface description

associate did not have or follow standards, then the next associate will need to analyze how the device is supposed to be connected or configured. For example, if the headquarters router always has the lowest address in a subnet configured and the remote office uses the next address up, then there is no question about what the interface addresses should be. The interface description should provide information about the configuration, connection, and use of the interface.

3.2.2 Interface descriptions

The description of an interface should be used to identify important information such as a distant router, a circuit number, or a specific network segment. A description of an interface can help a network user remember specific information about the interface such as which network the interface services.

The description is a comment about the interface. Stress the importance of a standard type of description. Students will use small routers in a small topology and can get physical access to the routers. Since this is the extent of their experience, it is hard for them to understand how helpful interface descriptions are.

Ask the students to envision an environment with hundreds of routers, thousands of interfaces, and routers that are 1000 kilometers (621.4 miles) away. Tell the students that a customer from a branch office is unable to connect to headquarters. Ask students how they can verify that the interface is connected to the correct branch office before they change anything on the interface. There are several good answers such as ask the customer, refer to documentation, and use the show cdp neighbor command. The best answer is to look at the interface description with the show interface command.

Ask students the following questions:

•What is used on an interface to make a comment?

•Which type of information may be included in a description?

3.2.3Configuring an interface description

To configure an interface description, enter global configuration mode. From global configuration mode, enter interface mode. Use the following steps:

1.Enter global configuration mode with the configure terminal command.

2.Enter a specific interface mode such as interface ethernet 0.

3.Enter the description command followed by the information to be displayed. For example, XYZ network, Building 10.

4.Exit interface mode and return to global configuration mode by pressing Ctrl-Z.

Save the configuration changes to NVRAM with the copy running-config startup- config command.

Important concepts for students to understand are that each description is for a particular interface and the description is entered in interface configuration.

34 - 238 CCNA 2: Routers and Routing Basics v3.1 Instructor Guide – Module 3 Copyright ♥ 2004, Cisco Systems, Inc.