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2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1

Configuring and testing

CCNA Exploration Semester 1

Chapter 11

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Topics

The Internetwork Operating System(IOS).

Devices that have the IOS embedded.

IOS commands available to a device.

IOS modes of operation.

Basic IOS commands.

Basic show commands.

Configuration files

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Internetwork Operating System

Most Cisco devices use the Cisco IOS.

Details vary with the device and feature

set.

Normal access through a command line.

Stored in flash memory and can beupgraded.

Usually copied into RAM when the device

is powered on, and run from RAM.

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Access to the interface

Console port via serial connection

Initial configuration

Disaster recoveryWhen network access has failed

Password recovery

As well as general management

Console access does not require apassword. Configure a password. Lock

the door.

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Telnet, SSH, Aux

Later management can be via Telnet

There must be an IP address on the port

A password must be configured

Secure shell gives better security

AUX port can be used locally or viamodem but by default does not showerror messages

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Configuration files

Hold the commands that have beenconfigured on the router to customise it.

Running configuration in RAM holdscommands that are in current use

Startup configuration in NVRAM holds

saved commands. These are kept whenthe power is off and usually copied backinto RAM when the router is re-started.

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Router storage areas

ROM

Permanent

Holds POST, bootinstructions, basic IOS

Flash

Keeps contents

Holds IOS image

NVRAM

Keeps contents

Holds startupconfiguration file

RAM

Volatile

Holds runnning config,tables, queues etc

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Router IOS modes

User EXEC mode

Privileged EXEC mode

enable disable+ password

Global Configuration mode

Configure terminal Exit or Ctrl+z

Specific Configuration modes

Exit EndVarious commands

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Router prompts

User EXEC mode

Privileged EXEC mode

Global Configuration mode

Specific Configuration modes

Router>

Router#

Router(config)#

Router(config-if)#and others

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EXEC modes

You log in to User EXEC modeRouter>

You can give basic monitoring commands but

cannot change the configurationEnterenable to go to Privileged EXEC mode

Router#

Password may be used for security

You can give more commands and can go toconfiguration modes

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Configuration modes

Start in privileged EXEC mode and enter theconfigure terminal (config t) commandRouter# config tRouter(config)#

The prompt changes

This is global configuration mode

Additional commands take you to interfaceconfiguration, router configuration etc.

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Leaving configuration modes

From interface configuration mode thereare several ways of getting to privilegedEXEC

Router(config-if)# exitRouter(config)# exitRouter#

Router(config-if)# endRouter#

Router(config-if)# Ctrl+z

Router#

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Command Structure

Followed by

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? To get help

? Gives a list of commands availablefrom the current prompt.

Command followed by space then ?Gives a list of keywords or argumentsthat can be used.

Start of command followed by ? with nospace shows how the word can becontinued.

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Shortened commands

Router#show running-config

Router#show run

Router#sh ru

It needs enough letters of each word to

be unambiguous. (Tab key shows wholeword)

Router#s ru

% Ambiguous command: s

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Other error messages

Switch#clock set

% Incomplete command

Switch#clock set 19:50:00 25 6

% Invalid input detected at ^ marker

Router#show runming-config

% Invalid input detected at ^ marker

^

^

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Keyboard shortcuts

Tab completes a partial command

Backspace erases to left of cursor

Ctrl+D erases at cursor (Delete doesnot)

Ctrl+Z returns from any config modeto privileged exec mode

Ctrl+C leave Setup mode

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Show commands

Show ? To get a list

Many different show commands to

give information about every aspectof the router and its operation

We use some of the most common.

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General show commands

Show running-config shows theconfiguration file from RAM

Show startup-config shows the saved

configuration file from NVRAM

Show version gives information about the

IOS and the router itself. It shows theconfiguration register, which controls howthe router starts up.

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Show interfaces

Gives statistics for all interfaces In particular, says if the interface is up and if the

protocol is up important in troubleshooting.

Show interfaces serial 0/0 to show oneselected interface

You can shorten to show int s 0/0

Show ip interfaces gives IP statistics

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Save configuration

Router#copy running-config startup-config

Router#copy run start (shortened)

Router#wr (Old fashioned, short for write,but it works and is safe.)

Beware! A typing error in the copy commandcan delete the operating system. If you getan odd message about Flash hands off

call for help.

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Hostname

Router>enable

Router#config t

Router(config)#hostname Paris

Paris(config)#

Configure a suitable hostname so thatyou know which router you are managingand so that you can identify it in network

documentation.

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Console password

Paris(config)#line con 0

Paris(config-line)#password cisco

Paris(config-line)#login

Paris(config-line)#exit

Restricts access via the console

Use cisco as the password in labs.

Use a proper strong password on

production networks

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Vty password for Telnet

Paris(config)#line vty 0 4

Paris(config-line)#password cisco

Paris(config-line)#loginParis(config-line)#exit

Allows and restricts access via 5 vty lines

Use cisco as the password in labs.

Use a proper strong, different password

on production networks

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Enable and enable secret

Paris(config)#enable secret class

The password class is needed when you

type enable to enter privileged exec mode

This password is encrypted

Paris(config)#enable password ciscoNot encrypted, used on older routers

If you configure both, then only the

enable secret is used.

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Message of the day

Paris(config)#banner motd # Nounauthorised access #

# is a delimiter to show where themessage starts and ends.

Any character can be used as long as it

does not appear in the message.

The message should make it clear thatunauthorised access is forbidden.

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Reload

Shuts down the router and thenstarts it again.

If the configuration has changed thenyou are prompted to save it.

The running configuration in RAM is

lost.

The startup configuration fromNVRAM is (usually) loaded into RAM

on startu .

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Back up to TFTP server

Start TFTP server software on host

Paris#copy running-config tftp

Remote host []? 172.16.1.1

Name of configuration file to write [Paris-config]? Paris12Oct07

Write file Paris12Oct07 to 172.16.1.1?[confirm] y

Writing Paris12Oct07 ! ! ! ! ! ! [OK]

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Back up as text file

Start text capture

Name file

show run

Stop text capture

Open saved file and

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TeraTerm text file

TeraTerm is an open source Telnet client.

It can also act as a SSH client

It can capture text and save it as a file.

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Erase startup configuration

Paris#erase NVRAM:startup-config

Paris#erase startup-config

Paris#erase start

If you reload, then the router starts up with the defaultconfiguration. No passwords, no IP addresses etc.

Caution if you get this command wrong then you could

erase something else, e.g. IOS

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Restore file from TFTP server

Router#copy tftp running-config

You will be prompted for IP address and file name.

Configuration is copied into RAM and takes effect atonce.

Save to NVRAM.

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Restore text file

Go to global configurationmode

Hyperterminal Transfer

menu

Send text file

Or

Copy text from text file

Paste to host into Hyperterminal session

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Configure a router interface

Paris(config)#interface FastEthernet 0/0

Paris(config-if)#ip address 172.16.1.1 255.255.0.0

Paris(config-if)#no shutdown

Paris(config-if)#exit

Interface names vary, depending on whether the routeris modular and on the bandwidth.

E.g. interface Ethernet 0 on an older router

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Configure a router interface

Paris(config)#interface serial 0/0

Paris(config-if)#ip address 192.168.4.1 255.255.255.0

(Paris(config-if)#clock rate 64000)

Paris(config-if)#no shutdown

Paris(config-if)#exit DCE only

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Description

Paris(config)#interface fa0/0

Paris(config-if)#description Connects to Paris centralswitch

Can include circuit and contact information

Not needed for the operation of the router

Valuable for documentation as it is included in the

configuration listing

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Switch interfaces

Switch physical interfaces do not have IP addresses

They are active by default and do not need the noshutdown command.

It can be useful to give them a description.

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Switch IP address

The switch IP address goes on a virtual interface, not areal one, normally VLAN1.

SwA(config)#interface VLAN1

SwA(config-if)#ip address 172.16.255.1 255.255.0.0

SwA(config-if)#no shutdown

SwA(config-if)#exit

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Switch default gateway

SwA(config)#ip default gateway 172.16.255.254

Just like a workstation, a switch needs a defaultgateway if it exchanges messages with devices on a

different network. The default gateway is the address of the local router.

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Interface show commands

show interfaces states whether up or down, givessome protocol information and statistics about interfaceuse.

show ip interface gives IP addresses and much more.

show ip interface brief gives summary of IPaddresses and whether up/down. Very usefulcommand.

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Up or down

Interface status: Layer 1

Up

Down

Administratively down (no shutdown to bring up)

Protocol: Layer 2

Up

Down (no keepalive signal received)

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Ping step by step

Ping 127.0.0.1 (loopback, is TCP/IP OK?)

Ping own IP address (are NIC hardware and softwareall right? Is IP address bound?)

Ping local hosts (checks own configuration and that ofothers)

Ping gateway

Ping other intermediate routers Ping hosts on remote networks

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Network baseline

Measure and record performance

At different times

Under different conditions

Repeatedly over a period of time

Build up a record of network performance

Useful in troubleshooting and optimising the network

Helps predict future problems

Helps planning for change

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Find out about nodes

Ping used from workstation, router or switch showsif destination can be reached

Traceroute shows hops along the path

Arp -a on workstation shows list of MAC and IPaddresses

show mac-address-table on switch shows list of MACaddresses and switch ports

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Summary

Hierarchical Design model addresses performance,scalability, maintainability & manageability issues.

Traffic Analysis is used to monitor networkperformance.

Hierarchical Design Model is composed of 3 layers:

Access

Distribution

Core

Switches selected for each layer must meet the needsof each hierarchical layer as well as the needs of thebusiness.

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Labs & Activities

Type Detail

Lab 11.1.6 Mandatory*

Lab 11.1.7 Mandatory

Lab 11.2.1 Mandatory

Lab 11.2.2 Review carefully

Lab 11..2.3 Mandatory

* If no previous Packet Tracer experience, else strongly recommended

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Documents

CCNA2 mod11