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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

• 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)

• “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 – 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

• 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