Chapter 4- Using the Command Line Interface (CLI)

Command-line interface (CLI)

An interface that enables the user to interact with the operating system by entering commands and optional arguments. - 1 way to access a switch's CLI

Configuration mode

A part of the Cisco IOS Software CLI in which the user can type configuration commands that are then added to the device's currently used configuration file (running-config).

• Displayed as: hostname (config)

Enable mode (privileged mode)

A part of the Cisco IOS CLI in which the user can use the most powerful and potentially disruptive commands on a router or switch, including the ability to then reach configuration mode and reconfigure the router.

• Command prompts end with "#"

Internetwork Operating System (IOS)

The operating system (OS) of Cisco routers and switches, which provides the majority of a router's or switch's features, with the hardware providing the remaining features.

IOS XE

A Cisco operating system (OS) with a modern Linux-based multitasking software architecture used as the OS for many enterprise-class LAN switch and router products.

Rollover cable

For connections to the RJ-45 console port rather than the USB console port of a Cisco device, with a DB9 connecter end.

• Typically requires adapter to connect to computer

• The UTP rollover cable uses a rollover pinout with eight pins, connecting pin 1 to pin 8, pin 2 to pin 7, and so on.

Running-config file

In Cisco IOS switches and routers, the name of the file that resides in RAM, holding the device's currently used configuration.

Secure Shell (SSH)

A TCP/IP application layer protocol that supports terminal emulation between a client and server, using dynamic key exchange and encryption to keep the communications private.

• Avoids someone stealing network packets

• 1 way to access a switch's CLI

Startup-config file

In Cisco IOS switches and routers, the name of the file that resides in NVRAM memory, holding the device's configuration that will be loaded into RAM as the running-config file when the device is next reloaded or powered on.

Telnet

The standard terminal-emulation application layer protocol in the TCP/IP protocol stack.

• Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system. Telnet is defined in RFC 854.

• 1 way to access a switch's CLI

User mode (user EXEC mode)

A mode of the user interface to a router or switch in which the user can type only nondisruptive EXEC commands, generally just to look at the current status, but not to change any operational settings.

• Command prompt ends with a ">"

What are a Cisco switch's default console port settings?

• 9600 bits/sec

• No hardware flow control

• 8 bit ASCII

• No parity bits

• 1 stop bit