CCNA Guide to Cisco
Networking
Chapter 6: Router and IOS
Basics
Objectives
• Describe the benefits of network
segmentation with routers
• Understand the elements of the Cisco
router user interface
• Configure the HyperTerminal program to
interface with the Cisco router
• Describe the various router configuration
modes
• Describe the various router passwords
Objectives (continued)
• Understand the enhanced editing features
of the Cisco IOS
• Understand the elements of the Cisco
switch user interface
• Compare router components to typical PC
components
Benefits Of Routing
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•
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Packet filtering
Traffic control
Connect LANs
WAN connections
Segmentation
Cisco Router User Interface
• Cisco Internetwork Operating System
(IOS)
• Command-line interface (CLI)
– Command executive or EXEC
• Router access
– Console port (console)
• Rollover cable, RJ-45 to DB-9, RJ-45 to DB-25
– Auxiliary port (AUX)
– Virtual terminal (VTY)
Cisco Router User Interface
(continued)
Cisco Router User Interface
(continued)
Connecting Via Terminal
Programs
• Establish a connection
– Physical connection through console
• 9600 bits per second, data bits 8, stop bits 1, parity
“none”, flow control “none”
– Logical connection through VTY
• Terminal programs
• HyperTerminal, Microphone Pro,
ProComm Plus, Telix, Tera Term
System Configuration Dialog
• Router enters system configuration dialog
– No previous configuration (factory default)
– Start-up file has been erased
– Registry setting has is set to 0x2142
– Forced by entering the CLI “setup” command
• Default options are in brackets
• Two types of setup
– Basic management setup
– Extended setup
System Configuration Dialog
(continued)
User Interface
• Return or Enter key to reach the prompt
when connecting with a terminal program
• Initial prompt consists of two parts
– Hostname
– Greater than symbol (>)
• User EXEC mode or user mode
– View basic settings and monitoring
• Question mark (?)
• Context-sensitive help
User Interface (continued)
• Privileged EXEC mode or Exec mode
– “enable” command at user prompt
– May be prompted for a password
• Exec mode prompt consists of two parts
– Hostname
– Pound sign symbol (>)
• Exec mode commands that can will affect router
operations
– Setup
– Copy
– Erase
User Interface (continued)
Configuration Modes
• Global configuration mode
– Router(config)#
• Interface mode
– Router(config–if)#
• Line configuration mode
– Router(config-line)#
• Router configuration mode
– Router(config-router)#
Configuration Modes
(continued)
Configuration Modes
(continued)
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•
•
•
“exit” command
Crtl+Z
Incorrect character symbol (^)
Command shortcuts
– Example: show running-config or sh ru
Configuration Modes
(continued)
Plethora Of Passwords
• Routers have five basic passwords and several
advanced passwords
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Enable password
Enable secret password
Virtual terminal password
Console password
AUX password
• Three of the five passwords can be setup during
initial configuration dialog
• “service-password encryption” command
Plethora Of Passwords
(continued)
Plethora Of Passwords
(continued)
Plethora Of Passwords
(continued)
Plethora Of Passwords
(continued)
Plethora Of Passwords
(continued)
Plethora Of Passwords
(continued)
Enhanced Editing
Command History
• Retrieve previously typed commands
• Stores up 10 previously typed commands
by default
– Up arrow (Ctrl+P)
– Down arrow (Ctrl+N)
• Tab key to complete commands
• “terminal history” command
– 0 through 256
Configuring Router
Identification
• Configure router host name
– Router(config)# hostname
• Message of the day login banner
– Delimiting character
– “banner motd # .... #” command
• Interface description
– “description” command
Configuring Router Identification
(continued)
Configuring Router Identification
(continued)
Configuring Router Identification
(continued)
Configuring The Time And
Date
• Configure the time in enable mode with
the “clock set” command
• Universal Time Code
– Greenwich, United Kingdom
• Configure the time zone in global
configuration mode
• “show clock” command
Configuring The Time And Date
(continued)
Switch User Interface
• Two types of operating systems
– IOS-based
• 1900, 2820, and 2900 switches
– Set-based
• 1984G, 2926, 4000, 5000, and 6000 switches
• Catalyst 1900 menu
[M] Menus
[K] Command Line
[I] IP Configuration
• Modes and passwords
• Setting the host name
Router Components
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ROM
Flash memory
NVRAM
RAM/DRAM
Interfaces
Router Components
(continued)
• ROM
– Read-only memory (ROM)
– Bootstrap program
– ROM monitor firmware
– ROM monitor mode
• (>) or (rommon 1>)
Router Components
(continued)
• Flash memory
– Erasable, programmable, read-only memory
(EPROM)
– Contains the Cisco IOS
– Can store multiple IOS
– “show version” command
– “show flash” command
Router Components
(continued)
• NVRAM
– Nonvolatile random access memory (NVRAM)
– Special type of RAM
– Not cleared when router is rebooted
– Startup configuration file
– “show start” command
Router Components
(continued)
• Random access memory (RAM)
– Volatile
– Information is not retain during router reboot
– Running configuration
– “show running-config” command
– “show memory” command
– “show buffers” command
Router Components
(continued)
• Interfaces
– Token Ring
– Basic Rate Interface (BRI)
– Asynchronous Transfer Mode (ATM)
– Fiber Distributed Data Interface (FDDI)
– Channel Interface Processor (CIP) for System
Network Architecture (SNA)
– High-Speed Serial Interface (HSSI)
Summary
• Cisco routers use the Cisco IOS to provide an interface
for network operators and administrators
• The first mode entered is user EXEC (router> prompt)
and the next mode is privileged EXEC (router# prompt)
• In user EXEC, you can accomplish basic tasks such as
checking the router status, checking connectivity, and
viewing some configuration information
• To actually configure the router, privileged EXEC mode
must be accessed, as this mode leads to the two most
common modes for router configuration: global
configuration mode and interface configuration mode
• The privileged EXEC mode is often called enable mode
because it is entered using the enable command
Summary (continued)
• The enable, enable secret, and VTY passwords are set
during initial configuration if the system configuration
dialog is used, but they can also be added and changed
in global configuration mode (router(config)# prompt)
• When configured, the enable secret password
supersedes the enable password
• This is because the enable secret is an encrypted
password that is not viewable in the configuration file,
which means that it has less chance of being
compromised
• For this reason, it should be different from the enable
password
Summary (continued)
• The Cisco 1900 switch allows configuration from a
command line just like a Cisco router
• Host names and passwords, as well as other
parameters, are configured on the Cisco 1900 switch in
much the same way as they are configured on a router
• The components of a router include ROM, flash memory,
NVRAM, RAM/DRAM, and interfaces
• ROM stores a limited version of the Cisco IOS and
routines for checking the hardware during system boot
• It is responsible for initializing the router
Summary (continued)
• Flash memory stores the Cisco IOS that is
loaded by default during system boot
• NVRAM stores the startup copy of the router
configuration file that is loaded by default during
system boot
• RAM/DRAM stores the working copy (running
configuration) of the router configuration
• This configuration is loaded into RAM from
NVRAM by default during bootup
• It is erased if the router is rebooted, unless it is
saved to the startup configuration