This document provides an overview of configuring and accessing a Cisco IOS network operating system. It discusses that all networking equipment relies on operating systems like Cisco IOS. Cisco IOS is stored in flash memory and enables functions like routing, switching, and interface configuration. The document reviews methods for accessing Cisco devices like the console port, Telnet, SSH, and Aux port. It also covers IOS modes, navigating the CLI, and configuring basic settings like IP addresses and interfaces.

1. Chapter 1:
Configuring a Network Operating System

2. IOS Bootcamp

3. Cisco IOS
Operating Systems
All networking equipment dependent on operating systems
• End users (PCs, laptops, smart phones, tablets)
• Switches
• Routers
• Wireless access points
• Firewalls
Cisco Internetwork Operating System (IOS)
• Is an operating system used by collection of network
operating systems used on all Cisco devices

4. Cisco IOS
Purpose of OS
• PC operating systems (Windows 8 & OS X) perform technical
functions that enable
• Use of a mouse
• View output
• Enter text
• Switch or router IOS provides options to
• Configure interfaces
• Enable routing and switching functions
• All networking devices come with a default IOS
• Possible to upgrade the IOS version or feature set

5. Cisco IOS
Location of the Cisco IOS
IOS stored in Flash
• Non-volatile storage – not lost when power is lost
• Can be changed or overwritten as needed
• Can be used to store multiple versions of IOS
• IOS copied from flash to volatile RAM
• Quantity of flash and RAM memory determines IOS that can
be used

6. Cisco IOS
IOS Functions
Major functions performed or enabled by Cisco routers and
switches include:

7. Accessing a Cisco IOS Device
Console Access Method
Most common methods to access the Command Line Interface
• Console
• Telnet or SSH
• AUX port

8. Accessing a Cisco IOS Device
Console Access Method
Console port
• Device is accessible even if no networking services have been
configured (out-of-band)
• Need a special console cable
• Allows configuration commands to be entered
• Should be configured with passwords to prevent unauthorized
access
• Device should be located in a secure room so console port can
not be easily accessed

9. Accessing a Cisco IOS Device
Telnet, SSH, and AUX Access Methods
Telnet
• Method for remotely accessing the CLI over a network
• Require active networking services and one active interface that is
configured
Secure Shell (SSH)
• Remote login similar to Telnet but utilizes more security
• Stronger password authentication
• Uses encryption when transporting data
Aux Port
• Out-of-band connection
• Uses telephone line
• Can be used like console port

10. Accessing a Cisco IOS Device
Terminal Emulation Programs
Software available for
connecting to a networking
device
• PuTTY
• Tera Term
• SecureCRT
• HyperTerminal
• OS X Terminal

11. Navigating the IOS
Cisco IOS Modes of Operation

12. Navigating the IOS
Primary Modes

13. Navigating the IOS
Global Configuration Mode and Submodes

14. Navigating the IOS
Navigating between IOS Modes

15. Navigating the IOS
Navigating between IOS Modes (cont.)

16. The Command Structure
IOS Command Structure

17. The Command Structure
Context Sensitive Help

18. The Command Structure
Command Syntax Check

19. The Command Structure
Hot Keys and Shortcuts
• Tab - Completes the remainder of a partially typed command or
keyword
• Ctrl-R - Redisplays a line
• Ctrl-A – Moves cursor to the beginning of the line
• Ctrl-Z - Exits configuration mode and returns to user EXEC
• Down Arrow - Allows the user to scroll forward through former
commands
• Up Arrow - Allows the user to scroll backward through former
commands
• Ctrl-Shift-6 - Allows the user to interrupt an IOS process such
as ping or traceroute.
• Ctrl-C - Aborts the current command and exits the configuration
mode

20. CLI configuration manager
• Command line interface (CLI) is a text-based interface that is used to
operate software and operating systems while allowing the user to respond
to visual prompts by typing single commands into the interface and
receiving a reply in the same way.
• CLI is quite different from the graphical user interface (GUI) that is
presently being used in the latest operating systems.
• CLI is an older method for interacting with applications and operating
systems and is used to perform specific tasks required by users. CLI is a
text-based interface, unlike the GUI, which uses graphical options that
enable the user to interact with the operating system and applications.
• CLI allows a user to perform tasks by entering commands. Its working
mechanism is very easy, but it is not user friendly. Users enter the specific
command, press “Enter”, and then wait for a response. After receiving the
command, the CLI processes it accordingly and shows the output/result on
the same screen; command line interpreter is used for this purpose.

21. • configurations on Cisco routers and switches using the CLI will earn you some
decent cash!
• Entering the CLI
• After the interface status messages appear and you press Enter, the Switch>
prompt will
• pop up. This is called user exec mode, or user mode for short, and although it’s
mostly used to view statistics, it is also a stepping stone along the way to
logging in to privileged exec mode, called privileged mode for short.
• You can view and change the configuration of a Cisco router only while in
privileged mode, and you enter it via the enable command like this:
• Switch>enable
• Switch#
• The Switch# prompt signals you’re in privileged mode where you can both
view and change the switch configuration. You can go back from privileged
mode into user mode by using the disable command:
• Switch#disable
• Switch>

22. Configuration wizard
• If you unpack your switch and plug it in, you will be running the generic
factory configuration, the setup wizard. This configuration is enough to
allow you to use the switch on the default VLAN — vlan 1 — and will
have all auto options enabled for each port.
• There will not be a management interface for Telnet or SSH; but once a
management IP is configured, you can connect with Telnet and the web
browser to make configuration changes.
• When you first unpack a new switch or if you have erased the
configuration, when the switch boots for the first time, it will
automatically enter setup.
• If your switch does not, you have the option of running setup from
Privileged EXEC mode. Here is the basic setup process; within just a
few minutes, you can have the management interface on your switch up
and running:

24. Connectivity configuration on networking devices
IPAddressing in the Large
• Each end device on a
network must be configured
with an IP address
• Structure of an IPv4 address
is called dotted decimal
• IP address displayed in
decimal notation, with four
decimal numbers between 0
and 255
• With the IP address, a
subnet mask is also
necessary
• IP addresses can be
assigned to both physical
ports and virtual interfaces

25. Ports and Addresses
Interfaces and Ports
• Network communications depend on end user device interfaces,
networking device interfaces, and the cables that connect them
• Types of network media include twisted-pair copper cables, fiber-optic
cables, coaxial cables, or wireless
• Different types of network media have different features and benefits
• Ethernet is the most common local area network (LAN) technology
• Ethernet ports are found on end user devices, switch devices, and other
networking devices
• Cisco IOS switches have physical ports for devices to connect to, but
also have one or more switch virtual interfaces (SVIs - no physical
hardware on the device associated with it; created in software)
• SVI provides a means to remotely manage a switch over a network

26. Addressing Devices
Configuring a Switch Virtual Interface
• IP address - together with subnet mask, uniquely identifies end device on
internetwork
• Subnet mask - determines which part of a larger network is used by an IP
address
• interface VLAN 1 - interface configuration mode
• ip address 192.168.10.2 255.255.255.0 - configures the IP address and
subnet mask for the switch
• no shutdown - administratively enables the interface
• Switch still needs to have physical ports configured and VTY lines to enable
remote management

27. Addressing Devices
Manual IPAddress Configuration for End Devices

28. Addressing Devices
Automatic IPAddress Configuration for End Devices

29. Addressing Devices
IPAddress Conflicts

30. Verifying Connectivity
Testing the Interface Assignment

31. Verifying Connectivity
Testing End-to-End Connectivity