Cisco Interfaces

Interfaces provide connections to a network. Interfaces include LANs, WANs, and management ports (that is, console and auxiliary ports).

To view the current LAN or WAN interface, issue the show interface command. The show interface command displays all LAN and WAN interfaces. To display information regarding console or auxiliary ports, use the show line command. Figure 4-2 summarizes the available IOS commands that administrators can use to view a router's current configuration.

Figure 4-2 Interface IOS Commands show flash dir slot0.

show startup-config show config show running-config write terminal

Random-Access Memory (RAM)

Flash

Read-Only Memory (ROM)

Nonvolatile RAM (NVRAM)

Router Interfaces

LAN, WAN, Console, AUX Port show interfaces

Now that you have reviewed Cisco routers' hardware basics, it's time to review how routers operate. In addition to router operation, this chapter covers how administrators can manage Cisco routers by saving and loading files to and from a TFTP server.

NOTE Cisco routers can operate in a number of modes. Cisco defines them as follows:

• ROM boot mode—When the router is in boot mode and loaded with a subset of the IOS image, only a limited number of commands are available.

• Configuration mode—Where you can make configuration changes. An example prompt is Router1(config)#.

• Interface configuration mode—Where you make configuration changes to interfaces such as the Ethernet or Serial connections. Example prompt is Router1(config-if)#.

• Initial configuration mode—When a router first boots up out of the box with no initial configuration, you are prompted for basic system configuration details, such as name and IP address assignment. The prompt looks like this:

Would you like to answer the initial configuration dialog? [yes/no]

• User EXEC mode—Basic IOS commands are permitted from the command-line interface (CLI). An example prompt is R1>.

• Privileged EXEC mode (also referred to as enabled mode)—Advance IOS commands are permitted when the enable password or secret password is entered from the CLI. An example prompt is R1#.

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