Chapter 2 Configuring a NOS

Line Configuration Mode

Used to configure console, SSH, Telnet, or AUX access. (A sub configuration of Global Configuration Mode) Switch(config-line)#

Line command

Used to enter line sub-configuration mode. Use this command followed by the management line type and number you wish to access.

Ctrl+Z.

Used to move from any sub-configuration mode to the privileged EXEC mode. May also enter the end command.

Argument

not predefined; a value or variable defined by the user (in the figure, 192.168.10.5)

disable command

privileged EXEC mode command to return to user EXEC mode.

Default SVI

VLAN 1

Layer 2 Switch

A Layer 2 switch does not need an IP address. The IP address assigned to the SVI is used to remotely access the switch. An IP address is not necessary for the switch to perform its operations.

Media Differences

Distance the media can successfully carry a signal Environment in which the media is to be installed Amount of data and the speed at which it must be transmitted Cost of the media and installation

no shutdown command

Enables the virtual interface using this interface configuration command.

Global Configuration Mode

From global config mode, CLI configuration changes are made that affect the operation of the device as a whole. Global configuration mode is identified by a prompt that ends with (config)# after the device name, such as Switch(config)#.

Cisco IOS Layer 2 switches

Have physical ports for devices to connect. These ports do not support Layer 3 IP addresses. Therefore, switches have one or more switch virtual interfaces (SVIs). These are virtual interfaces because there is no physical hardware on the device associated with it. An SVI is created in software. The virtual interface provides a means to remotely manage a switch over a network using IPv4.

enable command

Moves from user EXEC mode to privileged EXEC mode,

Interface Configuration Mode

Used to configure a switch port or router network interface. (A sub configuration of Global Configuration Mode) Switch(config-if)#

User EXEC Mode

This mode has limited capabilities but is useful for basic operations. It allows only a limited number of basic monitoring commands but does not allow the execution of any commands that might change the configuration of the device. The user EXEC mode is identified by the CLI prompt that ends with the > symbol.

Switch Virtual Interface Configuration

To access the switch remotely, an IP address and a subnet mask must be configured on the SVI. To configure an SVI on a switch, use the interface vlan 1 global configuration command. Vlan 1 is not an actual physical interface but a virtual one.

Privileged EXEC Mode

To execute configuration commands, a network administrator must access privileged EXEC mode. Higher configuration modes, like global configuration mode, can only be reached from privileged EXEC mode. The privileged EXEC mode can be identified by the prompt ending with the # symbol.

configure terminal command

To move in and out of global configuration mode. Is a privileged EXEC mode command.

Exit command

To return to the privileged EXEC mode. Is a global config mode command.

Keyword

a specific parameter defined in the operating system (in the figure, ip protocols)

Context-sensitive help

enables you to quickly find which commands are available in each command mode, which commands start with specific characters or group of characters, and which arguments and keywords are available to particular commands. To access context-sensitive help, simply enter a question mark, ?, at the CLI.

show ip interface brief

use commands to verify the interfaces and address settings of intermediary devices like switches and routers.

Command syntax check

verifies that a valid command was entered by the user. When a command is entered, the command line interpreter evaluates the command from left to right. If the interpreter understands the command, the requested action is executed, and the CLI returns to the appropriate prompt. However, if the interpreter cannot understand the command being entered, it will provide feedback describing what is wrong with the command.