Section 2: Basic Switch and

End Device Configuration

Introduction to Networks v7.0

2.1 Cisco IOS Access

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Cisco IOS Access
Operating Systems
• Shell - The user interface that allows
users to request specific tasks from
the computer. These requests can be
made either through the CLI or GUI
interfaces.
• Kernel - Communicates between the
hardware and software of a computer
and manages how hardware
resources are used to meet software
requirements.
• Hardware - The physical part of a
computer including underlying
electronics.

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Cisco IOS Access
GUI
• A GUI allows the user to interact with the
system using an environment of
graphical icons, menus, and windows.

• A GUI is more user-friendly and requires

less knowledge of the underlying
command structure that controls the
system.

• Examples of these are: Windows,

macOS, Linux KDE, Apple iOS and
Android.
• GUIs can fail, crash, or simply not
operate as specified. For these reasons,
network devices are typically accessed
through a CLI.

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Cisco IOS Access
Purpose of an OS
PC operating system enables a user to do CLI-based network operating system enables a
the following: network technician to do the following:
• Use a mouse to make selections • Use a keyboard to run CLI-based
and run programs network programs
• Enter text and text-based • Use a keyboard to enter text and
commands text-based commands
• View output on a monitor
• View output on a monitor

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Cisco IOS Access
Access Methods
• Console – A physical management port
used to access a device in order to
provide maintenance, such as
performing the initial configurations.
• Secure Shell (SSH) – Establishes a
secure remote CLI connection to a
device, through a virtual interface, over a
network. (Note: This is the recommended
method for remotely connecting to a
device.)

• Telnet – Establishes an insecure remote

CLI connection to a device over the
network. (Note: User authentication,
passwords and commands are sent over the
network in plaintext.)
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Cisco IOS Access
Terminal Emulation Programs
• Terminal emulation programs are used to connect to a network device by either a console
port or by an SSH/Telnet connection.
• There are several terminal emulation programs to chose from such as PuTTY, Tera Term
and SecureCRT.

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2.2 IOS Navigation

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IOS Navigation
Primary Command Modes
User EXEC Mode:
• Allows access to only a limited
number of basic monitoring
commands
• Identified by the CLI prompt
that ends with the > symbol

Privileged EXEC Mode:

• Allows access to all
commands and features
• Identified by the CLI prompt
that ends with the # symbol

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IOS Navigation
Configuration Mode and Subconfiguration Modes

Global Configuration Mode:

• Used to access
configuration options on the
device

Line Configuration Mode:

• Used to configure console,
SSH, Telnet or AUX access

Interface Configuration Mode:

• Used to configure a switch
port or router interface
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IOS Navigation
Navigation Between IOS Modes
 Privileged EXEC Mode:
• To move from user EXEC mode to privilege
EXEC mode, use the enabled command.
 Global Configuration Mode:
• To move in and out of global configuration
mode, use the configure terminal
command. To return to privilege EXEC
mode, use the exit command.
 Line Configuration Mode:
• To move in and out of line configuration
mode, use the line command followed by
the management line type. To return to
global configuration mode, use the exit
command.
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IOS Navigation
Navigation Between IOS Modes (Cont.)
Sub-configuration Modes:
• To move out of any subconfiguration mode to
get back to global configuration mode, use
the exit command. To return to privilege
EXEC mode, use the end command or key
combination Ctrl +Z.

• To move directly from one subconfiguration

mode to another, type in the desired
subconfiguration mode command. In the
example, the command prompt changes from
(config-line)# to (config-if)#.

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2.3 The Command Structure

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The Command Structure
Basic IOS Command Structure

• Keyword – This is a specific parameter defined in the operating system (in the figure, ip
protocols).

• Argument - This is not predefined; it is a value or variable defined by the user (in the
figure, 192.168.10.5).

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The Command Structure
IOS Command Syntax Check
A command might require one or more arguments. To determine the keywords
and arguments required for a command, refer to the command syntax.
• Boldface text indicates commands and keywords that are entered as shown.
• Italic text indicates an argument for which the user provides the value.

Convention Description
Boldface text indicates commands and keywords that you enter literally as
boldface
shown.
italics Italic text indicates arguments for which you supply values.

[x] Square brackets indicate an optional element (keyword or argument).

{x} Braces indicate a required element (keyword or argument).

Braces and vertical lines within square brackets indicate a required choice
[x {y | z }] within an optional element. Spaces are used to clearly delineate parts of the
command.

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The Command Structure
IOS Command Syntax Check (Cont.)
 The command syntax provides the pattern, or format, that must be used when
entering a command.

 The command is ping and the user-defined

argument is the ip-address of the
destination device. For example, ping
10.10.10.5.
 The command is traceroute and the
user-defined argument is the ip-
address of the destination device. For
example, traceroute 192.168.254.254.

 If a command is complex with multiple arguments, you may see it represented like this:

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The Command Structure
Hot Keys and Shortcuts
• The IOS CLI provides hot keys and shortcuts that make configuring, monitoring, and
troubleshooting easier.
• Commands and keywords can be shortened to the minimum number of characters
that identify a unique selection. For example, the configure command can be
shortened to conf because configure is the only command that begins with conf.

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The Command Structure
Hot Keys and Shortcuts (Cont.)
 The table below is a brief list of keystrokes to enhance command line editing.

Keystroke Description

Tab Completes a partial command name entry.

Backspace Erases the character to the left of the cursor.

Left Arrow or Ctrl+B Moves the cursor one character to the left.

Right Arrow or Ctrl+F Moves the cursor one character to the right.

Recalls the commands in the history buffer, beginning with

Up Arrow or Ctrl+P
the most recent commands.

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2.4 Basic Device Configuration

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Basic Device Configuration
Device Names
• The first configuration command on any device should be to
give it a unique hostname.
• By default, all devices are assigned a factory default name.
For example, a Cisco IOS switch is "Switch.”

• Guideline for naming devices:

• Start with a letter
• Contain no spaces
• End with a letter or digit
Note: To return the switch to the default
• Use only letters, digits, and dashes
prompt, use the no hostname global
• Be less than 64 characters in length config command.

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Basic Device Configuration
Password Guidelines
• The use of weak or easily guessed passwords are a security concern.
• All networking devices should limit administrative access by securing privileged EXEC,
user EXEC, and remote Telnet access with passwords. In addition, all passwords should
be encrypted and legal notifications provided.

• Password Guidelines:
• Use passwords that are more than eight
characters in length.
• Use a combination of upper and lowercase
letters, numbers, special characters, and/or
numeric sequences. Note: Most of the labs in this course use simple
passwords such as cisco or class. These
• Avoid using the same password for all devices. passwords are considered weak and easily
• Do not use common words because they are guessable and should be avoided in production
easily guessed. environments.
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Basic Device Configuration
Configure Passwords
Securing user EXEC mode access:
• First enter line console configuration mode
using the line console 0 command in global
configuration mode.
• Next, specify the user EXEC mode password
using the password password command.
• Finally, enable user EXEC access using
the login command.

Securing privileged EXEC mode access:

• First enter global configuration mode.
• Next, use the enable secret password command.

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Basic Device Configuration
Configure Passwords (Cont.)
Securing VTY line access:
• First enter line VTY configuration mode
using the line vty 0 15 command in
global configuration mode.
• Next, specify the VTY password using
the password password command.
• Finally, enable VTY access using
the login command.

 Note: VTY lines enable remote access using Telnet or SSH to the device. Many Cisco
switches support up to 16 VTY lines that are numbered 0 to 15.

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Basic Device Configuration
Encrypt Passwords
 The startup-config and running-config files  Use the show running-config command
display most passwords in plaintext. to verify that the passwords on the device
are now encrypted.
 To encrypt all plaintext passwords, use
the service password-encryption global config
command.

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Basic Device Configuration
Banner Messages
 A banner message is important to warn
unauthorized personnel from attempting
to access the device.
 To create a banner message of the day
on a network device, use the banner The banner will be displayed on attempts to access the device.
motd # the message of the day # global
config command.

Note: The “#” in the command syntax is called

the delimiting character. It is entered before
and after the message.

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2.5 Save Configurations

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Save Configurations
Configuration Files
 There are two system files that store the device configuration:
• startup-config - This is the saved configuration file that is stored in NVRAM. It contains all the commands that will be
used by the device upon startup or reboot. Flash does not lose its contents when the device is powered off.
• running-config - This is stored in Random Access Memory (RAM). It reflects the current configuration. Modifying a
running configuration affects the operation of a Cisco device immediately. RAM is volatile memory. It loses all of its
content when the device is powered off or restarted.
• To save changes made to the running configuration to the startup configuration file, use the copy running-config
startup-config privileged EXEC mode command.

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Save Configurations
Alter the Running Configurations
If changes made to the running config do not
have the desired effect and the running-config
has not yet been saved, you can restore the
device to its previous configuration. To do this
you can:
• Remove the changed commands individually.
• Reload the device using the reload command
in privilege EXEC mode. Note: This will cause
the device to briefly go offline, leading to
network downtime.
If the undesired changes were saved to the
startup-config, it may be necessary to clear all
the configurations using the erase startup-
config command in privilege EXEC mode.
• After erasing the startup-config, reload the
device to clear the running-config file from
RAM.
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Save Configurations
Capture Configuration to a Text File
Configuration files can also be saved and
archived to a text document.
• Step 1. Open terminal emulation software,
such as PuTTY or Tera Term, that is already
connected to a switch.
• Step 2. Enable logging in to the terminal
software and assign a name and file location to
save the log file. The figure displays that All
session output will be captured to the file
specified (i.e., MySwitchLogs).

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Save Configurations
Capture Configuration to a Text File (Cont.)
• Step 3. Execute the show running-
config or show startup-config command at
the privileged EXEC prompt. Text displayed in
the terminal window will be placed into the
chosen file.
• Step 4. Disable logging in the terminal
software. The figure shows how to disable
logging by choosing the None session logging
option

Note: The text file created can be used as a record of

how the device is currently implemented. The file could
require editing before being used to restore a saved
configuration to a device.

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