CCNA Router and IOS Basics

CCNA Guide to Cisco Networking Fundamentals

Chapter 5Router and IOS Basics

CCNA Guide to Cisco Networking Fundamentals, Fourth Edition 2

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


Objectives (continued)

• Describe the various router passwords

• Understand the enhanced editing features of the Cisco IOS

• Compare router components to typical PC components


Benefits of Routing

• Routers provide– Packet filtering– Connections between local networks– Traffic control– Wide area network (WAN) connections

• Routers operate at the Network layer of the OSI reference model– Because of Network layer addressing, routers can

direct packets to both local and remote segments


Cisco Router User Interface

• Cisco Internetwork Operating System (IOS)– Provides a command-line interface (CLI)

• Allows network operators to check the status of the router and network administrators to manage and configure the router

• You can access a router in several different ways– Console port (also known as the console)– Auxiliary port (AUX)– Virtual terminals (VTY)– Trivial File Transfer Protocol (TFTP) server




Connecting via Terminal Programs

• When configuring the router through the console or AUX ports– You must first make the physical connection– Then, you can access the router through a terminal

program

• Steps to configure HyperTerminal:– Open the HyperTerminal application– Click File on the menu bar, and then click New

Connection– Enter a name for the connection


Connecting via Terminal Programs (continued)

• Steps to configure HyperTerminal: (continued)– Configure how you will connect to the router via the

Connect To dialog box• If you are connecting to the router through the AUX

port, you would provide the router phone number here

• If connecting to the router through the console port, click the “Connect using” list box and choose the COM port to which the RJ-45 to DB-9 connector is attached

– Configure the following settings for the COM port: Bits per second, 9600; Data bits, 8; Parity, None; Stop bits, 1; Flow control, None


System Configuration Dialog

• If the router has not been configured previously, or if the startup file has been erased– The Cisco IOS will prompt you to run the initial

configuration dialog after the router boots

• The system configuration dialog presents a series of prompts that guide you through the initial configuration for the router



User Interface

• The initial prompt consists of two parts:– The host name of the router followed by the greater

than symbol (>)– Default: router>

• User EXEC mode (or user mode)– When the prompt displayed is the greater than symbol– Network operator can check router status and review

several of the router settings



User Interface (continued)

• The question mark activates context-sensitive Help on the Cisco router

• User mode does not allow you to configure the router– To do this, you must go into the privileged EXEC

mode

• To enter privileged EXEC, you can type the enable command at the user mode prompt– Next, you may be prompted for a password– Greater than symbol (>) changes to a pound sign (#)


User Interface (continued)

• You can do a few things at this prompt– Setup: the setup command will cause the router to

enter the system configuration dialog– Copy: configurations can be copied from TFTP

servers to the router and therefore change the router configuration

– Erase: configuration files as well as the entire IOS can be erased


Configuration Modes

• Global configuration mode– Accessed by typing configure terminal at the enable

mode prompt

• Interface configuration mode– Allows you to configure the Ethernet and serial

interfaces on your router

• Line configuration mode– Allows you to configure the virtual terminals, console,

and AUX lines that let you access the router



Configuration Modes (continued)

• Typing exit will take you back one level

• Typing end or pressing the Ctrl+Z keys will take you all the way back to the enable prompt

• Often, you can discover abbreviated commands by simply trying them– The router will show you the point at which you

entered an incorrect character


Configuration Modes (continued)


Plethora of Passwords


Plethora of Passwords (continued)

• Enable Password and Enable Secret Password configuration– You can set both passwords from the global

configuration mode prompt– Because it is encrypted, the enable secret password

is more secure than the enable password– You can type no enable secret and no enable password at the global configuration mode prompt

• To remove the enable secret and enable passwords






• Setting Line passwords– Line passwords are the first line of defense against

unauthorized intrusion into the router– You can set passwords for each line used to

configure the router– Configure the console line password

• Enter line configuration mode

– You can also configure passwords on the five virtual terminal lines that exist on every router

• In much the same way as on the console port








Enhanced Editing

• By default, the router supports enhanced editing features that allow you to modify lengthy commands

• The enhanced editing commands let you jump to the beginning or end of a command line

• You can also jump forward or back, character by character, or word by word

• You can turn off the enhanced editing features by typing terminal no editing at either the user EXEC or the privileged EXEC prompts– You can turn on terminal editing by typing terminal editing


Enhanced Editing (continued)


Command History

• Command history– Allows you to retrieve previously typed commands

• You can see up to 10 previously typed commands by typing show history – From either the user EXEC or privileged EXEC

mode

• To modify the number of commands stored by the router, you can use the terminal command– Up to 256 previous commands– Type terminal history size n


Configuring Router Identification

• Router host name– Default host name is router– To set the router host name, type hostname followed

by the name that you want to set

• Configure a banner– A banner is a message that you can configure to

display each time someone attempts to log in to the router

– Enter global configuration mode by typing config t• Then type banner motd, followed by a space and a

delimiting character


Configuring Router Identification (continued)





• Configure an interface description– Use the description command– The interface description helps you remember which

network the interface services


Configuring the Time and Date

• Use the clock set command in enable mode to configure the time– You must be in global configuration mode to configure

the time zone


Router Components

• This section discusses the hardware elements of the router:– ROM– Flash memory– NVRAM– RAM/DRAM– Interfaces


ROM

• Read-only memory (ROM)– Loads the bootstrap program that initializes the

router’s basic hardware components– Not modified during normal operations, but it can be

upgraded with special plug-in chips

• The content of ROM is maintained even when the router is rebooted

• The ROM monitor firmware runs when the router is turned on or rebooted


Flash Memory

• Flash memory– A type of erasable, programmable, read-only memory

(EPROM)– Not typically modified during normal operations

• However, it can be upgraded or erased when necessary

• The content of flash memory is maintained even when the router is rebooted

• Flash memory – Contains the working copy of the current Cisco IOS– Is the component that initializes the IOS for normal

router operations



NVRAM

• Nonvolatile random access memory (NVRAM) – A special type of RAM that is not cleared when the

router is rebooted

• The startup configuration file for the router is stored in NVRAM by default– This is the first file created by the person who sets up

the router

• The Cisco IOS uses the configuration file in NVRAM during the router boot process


RAM/DRAM

• Random access memory (RAM)– Also known as dynamic random access memory

(DRAM)– A volatile hardware component– Its information is not maintained in the event of a

router reboot

• Changes to the router’s running configuration take place in RAM/DRAM


RAM/DRAM (continued)

• The IOS contains commands to view each of the router’s components– show running-config– show memory– show buffers– show startup-config– Copy running-config startup-config

• Abbreviated as Copy run start



Interfaces

• A router can ship with a variety of configurable interfaces– A common interface is Ethernet0

• Other types of interfaces include:– Token Ring– Basic Rate Interface (BRI)– Asynchronous Transfer Mode (ATM)– Fiber Distributed Data Interface (FDDI)– Channel Interface Processor (CIP) for Systems 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

• To actually configure the router, privileged EXEC mode must be accessed

• The privileged EXEC mode is often called enable mode


Summary (continued)

• The enable, enable secret, and VTY passwords are set during initial configuration if the system configuration dialog is used

• When configured, the enable secret password supersedes the enable password

• 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


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

• Interfaces provide connectivity to various types of LANs and WANs

CCNA Router and IOS Basics

Technology

router ccna guide

cisco router user mode

router components

router status

router settings

cisco ios

router configuration

router line configuration