Router Fundamentals

Router Fundamentals

Chapter 4

Chapter Objectives
 Explain router components
 Explain router installation
 Discuss router boot sequence
 Define Internetwork Operating System (IOS)
 Explain Command Line Interface (CLI)
 Perform initial router configuration
 Set hostname, banners and passwords for the
router
 Manage the configuration register

Chapter 4 2

Recall - I
 Different network devices include:
 Hubs

 Routers

 Switches

 Bridges

 Repeaters

 Different types of hubs include:
 Active

 Passive

 Hybrid

Chapter 4 3

Recall - II
 Different WAN devices include:
 WAN Switch

 Access Server

 Modem

 Channel Service Unit

 ISDN Terminal Adapter

Chapter 4 4

Router Components
 Router components allow the router to enter the
bootup process, load its operating system, and
configuration files

Router
Components

Configuration
Processor ROM RAM Flash NVRAM
Register

Chapter 4 5

Router Boot Sequence
 The router requires all the router components during
its bootup

Chapter 4 6

Internetwork Operating System
 IOS acts as an interface between the network
devices and the user
 It is stored in the flash memory of the router
 The Cisco IOS software requires the processor of
the system for configuring and maintaining the
network devices
 Different features of IOS include:
 Support for different technologies

 Scalability

 Security

Chapter 4 7

Router Ports
 Router ports help to configure the router, verify its
configuration and access Cisco IOS

Router Ports

Console Port Auxiliary Port

Chapter 4 8

Rear Panel of the Cisco Router

Chapter 4 9

CLI Prompts
 CLI prompts allow you to navigate and recognize
the mode that you have entered
 CLI prompts include:
 Interfaces

 Sub-Interfaces

 Line

 Router

Chapter 4 11

Accessing Help and History
Command Description

? Help for all available commands in the mode

Command ? Describes all the first parameters of the command

com? Lists the commands that begin with com

command parm? Lists the characters that begin with parm

command When the tab is pressed in between the word, the CLI
parm<Tab> completes the word. If the CLI is idle, it indicates that the
typed characters can form more possible words
command parm1 ? Lists all the next parameters and their description

Chapter 4 12

Enhanced Editing Commands - I
 The enhanced editing commands include:
 Ctrl + A - Moves the cursor to the beginning of a

line
 Ctrl+E - Moves the cursor to the end of the line

 Esc+B - Move the cursor back by one word

 Ctrl+B - Move the cursor back by one character

 Ctrl+F - Move the cursor forward by one character

 Esc+F - Move the cursor forward by one word

 Ctrl+D - Deletes one character

Chapter 4 13

Enhanced Editing Commands - II
 Backspace - Deletes one character
 Ctrl+R - Recalls a line
 Ctrl+U - Deletes a line
 Ctrl+W - Deletes a word
 Ctrl+Z - Returns to EXEC from the configuration
mode
 Tab - Finishes typing a word

Chapter 4 14

Router History Commands

Command Description

Ctrl+P or Up arrow Displays the last command entered

Ctrl+N or Down arrow Displays the previously entered commands

show history Displays the last 10 command entered

show terminal Displays terminal configuration and size of history
buffer
terminal history size Allows to change the buffer size

Chapter 4 15

Router Administrative Functions
 Router administrative functions allow easy
troubleshooting and maintenance of routers
 Router administrative function include:
 Assigning hostname

 Assigning banners

 setting password

Chapter 4 16

Banners
 Banner is a message displayed to all the users when
they access the router through Telnet, console and
auxiliary ports
 It can be used to display information about the router
itself or nay kind of security message
 Four types of banners available for the Cisco routers
are:
 Message of the day banner

 Exec process creation banner

 Incoming terminal line banner

 Login banner

Chapter 4 17

Summary - I
 The router components enable the router to start the
boot up process, load its operating system, and load
its configuration files
 The Power-On-Self-Test or the POST component
provides a series of diagnostic tests for the router
 The POST is a series of 14 tests that run in the
reverse numerical order
 The bootstrap program or the ROM Monitor
component enables you to initialize the processor
hardware when the router boots

Chapter 4 18

Summary - II
 The bootstrap program loads the IOS image for the
router
 The different values for the image in the
configuration register are:
 0x0 - Boots the router into ROM monitor mode

 0x1 - Boots the router using the Mini-IOS

 0x2–0xF - Boots the router using the default boot

sequence

Chapter 4 19

Summary - III
 The boot system commands in the startup-config file
are:
 boot system flash IOS filename - Enables you to

boot from flash memory
 boot system tftp IOS filename tftp server ip

address - Enables you to boot from a TFTP server
 boot system rom - Enables you boot from system

ROM

Chapter 4 20

Summary - IV
 The bootstrap program offers a console-based
interface or monitor for working with the program
 Mini-IOS component provides an alternate file for
the router boot up, if the existing image file is
unavailable
 ROM monitor is a component stored in the
microcode of RAM
 The flash memory contains IOS using which the
router can boot

Chapter 4 21

Summary - V
 NVRAM or Non-Volatile RAM is a type of random
access memory that stores the configuration files for
the router
 Configuration register is a component that controls the
booting process of a router
 The router can be connected through console port,
auxillary port or Telnet program
 CLI is a character or text based interface that allows
manual configuration of the router
 User Exec Mode enables you to work with the router
and execute very simple commands
Chapter 4 22

Router Fundamentals

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