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2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 1
Chapter 2:It is Just an OperatingSystem
Network Basics
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Presentation_ID 2 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 2 - Objectives
Explain the purpose of Cisco IOS.
Explain how to access and navigate Cisco IOS to configure networkdevices.
Describe the command structure of Cisco IOS software.
Configure hostnames on a Cisco IOS device using the CLI.
Use Cisco IOS commands to limit access to device configurations.
Use Cisco IOS commands to save the running configuration.
Explain how devices communicate across network media.
Configure a host device with an IP address.
Verify connectivity between two end devices.
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Presentation_ID 3 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 2
2.1 IOS Bootcamp
2.2 Getting Basic
2.3 Address Schemes
2.4 Summary
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Presentation_ID 4 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
2.1 IOS Bootcamp
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Presentation_ID 5 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Cisco IOS
Purposeof OS
PC operating systems (Windows 8 & OS X) perform technicalfunctions 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
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Presentation_ID 6 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Cisco IOS
Location of the Cisco IOS
IOS stored in Flash Non-volatile storagenot 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
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Cisco IOS
IOS Functions
Major functions performed or enabled by Cisco routers andswitches include:
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Accessing a Cisco IOS Device
Console Access Method
The most common methods to access the Command Line Interface
Console
Telnet or SSH
AUX port
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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 notbe easily accessed
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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 isconfigured
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
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Accessing a Cisco IOS Device
Terminal Emulation Programs
Software available forconnecting to a networkingdevice
PuTTY
Tera Term
SecureCRT
HyperTerminal
OS X Terminal
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Navigating the IOS
Primary Modes
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Navigating the IOS
Global Configuration Mode and Submodes
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Navigating the IOS
Navigating between IOS Modes
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Navigating the IOS
Navigating between IOS Modes (cont.)
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The Command Structure
IOS Command Structure
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The Command Structure
Cisco IOS Command ReferenceSteps to navigate Ciscos Command Reference to find a particularcommand:
1. Go to www.cisco.com
2. Click Support.
3. Click Networking Software (IOS & NX-OS).
4. Click 15.2M&T (for example).
5. Click Reference Guides.
6. Click Command References.
7. Click the particular technology that encompasses the command youare referencing.
8. Click the link on the left that alphabetically matches the commandyou are referencing.
9. Click the link for the command.
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The Command Structure
Context Sensitive Help
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The Command Structure
Command Syntax Check
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21/48Presentation_ID 21 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
The Command Structure
Hot Keys and Shortcuts
Tab- Completes the remainder of a partially typed command orkeyword
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 formercommands
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 configurationmode
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The Command Structure
IOS Examination Commands
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The Command Structure
The show version Command
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Presentation_ID 25 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Hostnames
Why the Switch
Lets focus on Creating a two PC network connected via a switch
Setting a name for the switch
Limiting access to the device configuration
Configuring banner messages Saving the configuration
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Presentation_ID 26 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Hostnames
Device Names
Some guidelines for naming conventions are that names should: Start with a letter
Contain no spaces
End with a letter or digit
Use only letters, digits, and dashes
Be less than 64 characters in length
Without names, networkdevices are difficult to
identify for configuration
purposes.
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Presentation_ID 27 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Hostnames
Configuring Hostnames
Hostnames allowdevices to beidentified bynetworkadministratorsover a network or
the Internet
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Presentation_ID 28 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Limiting Access to Device Configurations
Securing Device Access
The passwords introduced here are:
Enable password- Limits access to the privileged EXEC mode
Enable secret- Encrypted, limits access to the privileged EXEC
mode
Console password- Limits device access using the console
connection
VTY password- Limits device access over Telnet
Note:In most of the labs in this course, we will be using simple
passwords such as ciscoor class.
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Presentation_ID 29 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Limiting Access to Device Configurations
Securing Privileged EXEC Access
use the enable secret command, not theolder enablepassword command
enable secret provides greater security becausethe password is encrypted
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Presentation_ID 30 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Limiting Access to Device Configurations
Securing User EXEC Access
Console port must be secured
reduces the chance of unauthorized personnel
physically plugging a cable into the device and gainingdevice access
vty lines allow access to a Cisco device via Telnet
number of vty lines supported varies with the type of
device and the IOS version
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Presentation_ID 31 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Limiting Access to Device Configurations
Encrypting Password Display
service password-encryption
prevents passwordsfrom showing up asplain text whenviewing theconfiguration
purpose of thiscommand is to keepunauthorizedindividuals fromviewing passwords inthe configuration file
once applied,removing theencryption servicedoes not reverse theencryption
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Presentation_ID 33 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Saving Configurations
Configuration Files Switch# reload
System configurationhas been modified.Save? [yes/no]: n
Proceed with reload?[confirm]
startup configuration isremoved by usingthe erase startup-configSwitch# erase startup-config
On a switch also issue
the delete vlan.datSwitch# delete vlan.dat
Delete filename [vlan.dat]?
Delete flash:vlan.dat?[confirm]
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Presentation_ID 34 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Saving Configurations
Capturing Text
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Presentation_ID 37 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
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, andother networking devices
Cisco IOS switches have physical ports for devices to connect to, butalso have one or more switch virtual interfaces (SVIs - no physicalhardware on the device associated with it; created in software)
SVI provides a means to remotely manage a switch over a network
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Presentation_ID 39 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Addressing Devices
Manual IP Address Configuration for End Devices
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Presentation_ID 40 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Addressing Devices
Automatic IP Address Configuration for End Devices
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Presentation_ID 41 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Addressing Devices
IP Address Conflicts
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Presentation_ID 43 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Verifying Connectivity
Testing the Interface Assignment
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Presentation_ID 46 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
It Is Just an Operating System
Chapter 2 Summary
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Presentation_ID 47 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
It Is Just an Operating System
Chapter 2 Summary
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