Sybex CCNA 640-802
Chapter 6: Cisco’s IOS
Instructor & Todd Lammle
Chapter 6 Objectives
• The Cisco router IOS
• Enhanced editing
• Administrative functions
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Hostnames
Banners
Passwords
Interface descriptions
• Verifying your configuration
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Cisco Router IOS
• Carries network protocols and
functions
• Connects high-speed traffic
between devices
• Adds security to control access
• Provides scalability for growth
• Supplies reliability
Connecting To A Cisco Router
Cisco 2800
Cisco 1841
Bringing up a Router
• Boot-up process:
1: POST
2: Looks for the Cisco IOS from Flash
memory
3: IOS loads & looks for a valid
configuration;
• startup-config
• stored in nonvolatile RAM (NVRAM)
4: If a valid config is not found in NVRAM:
• setup mode
Setup Mode
• Basic Management Setup
• Extended Setup
• Command-Line Interface
Configuration
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CLI Prompts
Interfaces
Sub-interfaces
Line Commands
Routing Protocol
Configurations
Command-Line Interface (CLI)
• More flexible than setup mode.
• To use the CLI, just say No to
entering the initial configuration
dialog.
Subinterfaces
Allow you to create logical
interfaces within the router
Router(configif)#interface f0/0.1
Router(config-subif)#
Logging into the Router
• User mode:
– Router>
– Used mostly to view statistics
• Privileged mode:
– Router#
– Used to view & change router
configuration
Overview of Router Modes
• Global changes:
– config terminal or config t
– Changes made to running-config
(DRAM)
– To change the startup-config (NVRAM)
• config memory or config mem
Note: Any configuration changes need to
be placed into RAM. Typing config mem or
config net (from a TFTP host) will append
the current running-config
Editing & Help Features
Editing & Help Features
• Commands starting with a certain
letter
Router#c?
clear clock configure connect copy
• Enhanced Editing Commands
• Router-Command History
• Gathering Basic Routing
Information
– show version
Enhanced Editing Commands
Enhanced Editing Commands
(cont.)
Router Command History
Gathering Basic Routing
Information
Administrative Functions
The administrative functions that
you can configure on a router
and switch are
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Hostnames
Banners
Password
Interface descriptions
Hostnames & Descriptions
• Hostnames
Router(config)#hostname todd
todd(config)#
• Descriptions
Atlanta(config)#int e0
Atlanta(config-if)#description Sales
Lan
Banners
• Purpose
• Types
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exec
incoming
login
motd
• Delimiting character
Setting the Passwords
• 5 passwords:
– 1st two used to set your enable
password
• Used to secure privileged mode;
Router>enable
– Other three are used to configure a
password in user mode via:
• console port
• auxiliary port
• Telnet
Passwords
• Enable passwords
Router(config)#enable password cisco
Router(config)#enable secret cisco
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Auxiliary Password
Console Password
Telnet Password
Encrypting Your Password
Router(config)#service passwordencryption
Interface Descriptions
Setting descriptions on an interface is helpful to the
administrator and, like the hostname, only locally
significant. The description command is a helpful one
because you can, for instance, use it to keep track of
circuit numbers.
Here’s an example:
Atlanta(config)#int e0
Atlanta(config-if)#description Sales Lan
Atlanta(config-if)#int s0
Atlanta(config-if)#desc Wan to Miami circuit:6fdda4321
You can view the description of an interface
either with the show running-config
command or the show interface command.
Router Interfaces
• Bringing up an Interface
no shutdown
shutdown
show interface
• Configuring an IP Address on an
Interface
Router(config)#int e0
Router(config-if)#ip address 172.16.10.2
255.255.255.0
Router(config-if)#no shut
• Serial Interface Commands
clock rate
kilobits)
& bandwidth
(entered in
Viewing, & Saving
Configurations
• Viewing & Saving Configurations
– running-config saved in
– startup-config saved in
copy run start
sh run
sh start
erase startup-config
DRAM
NVRAM
Verifying Your Configuration
Tools:
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show running-config
show startup-config
ping
show cdp nei detail
trace
telnet
Other Verification Methods
• Verifying with the show interface
command
– Router#show interface ?
• Verifying with the show ip
interface command
– Router#show ip interface
– Router#show ip interface brief
– Router#show controllers
Summary
• Go through all the written labs and review
questions
• Review answers in class
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