Basic IP Configuration

IP is enabled by default. Basic configuration consists of adding IP addresses for Layer 3 devices, configuring DNS, enabling a route exchange protocol, such as the Routing Information Protocol (RIP), and enabling and configuring routing protocols.
Note: The term, device, used in this chapter can represent a switch operating at Layer 3 or a router. A switch operating at Layer 2 can be configured with an IP address for management access through the network and to specify the default gateway.

To configure RIP and other routing protocols, refer to the appropriate chapter in this book.

There are a number of IP parameters and features that can be configured. Some IP parameters can be configured globally while others can be configured on individual interfaces. Some parameters that are configured globally can be overridden for individual interfaces. Use the information in this chapter if you need to change some of the IP parameters from their default values, to configure specific IP features, or if you want to view configuration information or statistics.

When IP Parameter Changes Take Effect

Most IP parameters described in this chapter are dynamic. They take effect immediately, as soon as you enter the CLI command or select the Web Management Interface option. You can verify that a dynamic change has taken effect by displaying the running-config file. To display the running-config, enter the show running-config or write terminal command at any CLI prompt. (You cannot display the running configuration from the Web Management Interface.)

To save a configuration change permanently so that the change remains in effect following a system reset or software reload, save the change to the startup-config file:

  • To save configuration changes to the startup-config file, enter the write memory command from the privileged EXEC level or any configuration level of the CLI.
  • To save the configuration changes using the Web Management Interface, select the Save link at the bottom of the dialog box. Select Yes when prompted to save the configuration change to the startup-config file on the device flash memory. You also can access the dialog box for saving configuration changes by clicking Command in the tree view, and then clicking Save to Flash.

Changes to memory allocation require you to reload the software after you save the changes to the startup-config file. When reloading the software is required to complete a configuration change described in this chapter, the procedure that describes the configuration change includes a step for reloading the software.

Parent topic: IP Addressing