Router Fundamentals

PJC CCNA Semester 2 Ver. 3.0by

William Kelly

Router Startup Procedure

ROM

FlashTFTP Server

ROM

NVRAMTFTP Server

Console

Load initial code fromROM into RAM to allow

bootstrapping

Load Operating System

Load “Config” File or GoTo Setup Mode

Router Startup

Router Boot Sequence and Setup Mode

A Power on Self Test (POST) is performed when a routers is powered on and all the hardware is checked

If no configuration file is found the router enters setup mode The file from setup mode is stored in NVRAM Ctrl-C will terminate the setup and start over Setup is not intended to enter complex protocol

information

Router Boot Sequence and Setup Mode (cont.)

Setup mode default answers are in square brackets

If the system has been previously configured the defaults are currently configured options

3 ways to enter setup mode The command erase startup-config will

erase the start config from NVRAM; then issue the reload command

Use the setup command Power on a new router than has never been

configured

Initial Boot-up Output The message NVRAM invalid means

either the router has never been configured or the startup configuration was erased

A partial list of information displayed during boot-up is as follows: How many interfaces the router has What types of interfaces the router has The amount of NVRAM The amount of Flash memory

Setup -Global Parameters

The line console can be secured with passwords Router(config)# line console 0

Router(config-line)# login

Router(config-line)# password cisco

The virtual terminals can be secured with passwords Router(config)# line vty 0 4

Router(config-line)# password cisco

Router Boot Sequence and Setup Mode

A Power on Self Test (POST) is performed when a routers is powered on and all the hardware is checked

If no configuration file is found the router enters setup mode The file from setup mode is stored in NVRAM Ctrl-C will terminate the setup and start over Setup is not intended to enter complex protocol

information

Establishing a HyperTerminal Session

Hardware DB-9 or DB-25 to RJ45 adapter. The DB-9 or 25

will connect to the PC serial port A Rollover cable with a male RJ45 on each end

A copy of HyperTerminal software if using Windows 9.X or above HyperTerminal settings are: 9600 baud, 8 data

bits, no parity, one stop bit, no flow control

Logging into the Router

Cisco routers have two main levels of access User Exec mode – also called User or

Exec mode and only allows router status to be checked but NO configuration changes can be made

Privileged Exec Mode – Also called privileged mode and allows both router status checks and configuration changes

Keyboard Help Tying a ? at either the user or privileged

mode displays a list of possible commands (context sensitivity)

The –More– message will display at the bottom of the screen after 22 lines Pressing the spacebar moves to the next screen Pressing the Enter key goes to the next line Pressing any other key goes back to a prompt

A partial command can be entered with a ? at the end to final all commands starting with the letters you entered

A ^ symbol indicates an error in your entry.

Router Editing Commands

Router Editing History

Router Editing History (cont.)

By default command history is enabled

The default history buffer size is 10 The maximum history buffer size is

256

Cisco IOS Modes

ROM Monitor – performs bootstrap and can be used for password recovery or system failure recovery (only accessible through the console port)

Boot ROM – very limited command set to enable transfer of new IOS image from tftp server

Cisco IOS – Allows normal operation

Cisco IOS Naming Convention

The show flash command will display the IOS image name. The name reveals the following 3 pieces of information: The hardware platform name The special image capabilities The image location and whether it is

compressed or zipped

Accessing the Command Line

The Cisco Command Line Interface (CLI) can be accessed 3 ways: Through a console session Using a modem through the aux port Through a Telnet connection

Troubleshooting Cisco IOS

No configuration file or bad boot system statement

No configuration or wrong configuration register value

Corrupted Flash memory Hardware failure

Cisco show version Command

Displays the following: Cisco IOS version and description Bootstrap ROM version Boot ROM version Router up time Last restart method System image file and location Router platform Configuration

Other Common Show commands show processes – displays information

about active processes show protocols – displays the configured

protocols show flash – shows info. about flash

memory show running-config – shows the active

configuration file show startup-config – shows the startup file

in NVRAM show interface – shows the status of the

interfaces