| 2.1 |  | Operating Cisco IOS Software |
| 2.1.2 |  | Router user interface |

| The Cisco IOS software uses a command-line interface (CLI) as the traditional console environment. The IOS is a core technology that extends across most of the Cisco product line. Its operation details may vary on different internetworking devices. This environment is accessible through several methods. One way to access the CLI is through a console session. A console uses a low speed serial connection directly from a computer or terminal to the console connection on the router. Another way to access a CLI session is by use of a dialup connection using a modem or null modem connected to the router AUX port. Neither of these methods require that the router have any network services configured. Another method of accessing a CLI session is to Telnet to the router. To establish a Telnet session to the router, at least one interface must be configured with an IP address, and virtual terminal sessions must be configured for login and passwords.