Basic Switch and End Device Configuration

Before a switch or end device can participate properly in a network, it needs basic settings such as a device name, secure access, IP addressing information, and a default gateway. Network technicians often configure these settings through a command-line interface.

An operating system provides the interface between users, software, and hardware.

A GUI uses windows, icons, menus, and pointers. A CLI uses typed commands. Network devices commonly use CLI access because it is efficient, scriptable, and available even when a graphical interface is not.

Common access methods for a Cisco IOS device include:

Terminal emulation tools allow a technician to connect through console, SSH, or Telnet sessions.

Cisco IOS uses different command modes. Each mode controls what commands are available.

A technician enters privileged EXEC mode with enable, then enters configuration mode with configure terminal.

IOS commands usually begin with a keyword and may include required or optional arguments. The CLI supports features that help avoid mistakes:

• ? displays available commands or parameters.
• Tab completes a partial command when the entry is unique.
• Arrow keys recall or edit commands.
• Ctrl+C exits many configuration operations.
• end returns to privileged EXEC mode.

When output is long, IOS may pause with a --More-- prompt so the technician can continue reading one screen at a time.

A basic switch setup usually includes a hostname, protected privileged EXEC access, console access security, remote access security, password encryption, and a login warning banner.

Passwords should be strong and should not be easy to guess. Remote access should use SSH instead of Telnet whenever possible.

Cisco IOS keeps active settings in the running configuration. These settings are lost after a reboot unless they are saved. The saved version is called the startup configuration.

Important commands:

show running-config
show startup-config
copy running-config startup-config
erase startup-config
reload

Use saving commands carefully. Erasing or reloading a device can interrupt network service.

A switch has physical ports that connect to end devices and other network devices. A Layer 2 switch can still have an IP address for management. This IP address is usually configured on a Switch Virtual Interface (SVI), commonly VLAN 1 in simple labs.

End devices need the following IP settings:

• IP address
• Subnet mask or prefix length
• Default gateway
• DNS server address, when name resolution is needed

The default gateway is the router interface a host uses to send traffic outside its local network.