Mod11

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

Configuring and testing

CCNA Exploration Semester 1 – Chapter 11


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


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 be upgraded.

Usually copied into RAM when the device is powered on, and run from RAM.


Access to the interface

Console port via serial connectionInitial configuration

Disaster recovery

When network access has failed

Password recovery

As well as general management

Console access does not require a password. Configure a password. Lock the door.


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 via modem but by default does not show error messages


Configuration files

Hold the commands that have been configured on the router to customise it.

Running configuration in RAM holds commands that are in current use

Startup configuration in NVRAM holds saved commands. These are kept when the power is off and usually copied back into RAM when the router is re-started.


Router storage areas

ROM

Permanent

Holds POST, boot instructions, basic IOS

Flash

Keeps contents

Holds IOS image

NVRAM

Keeps contents

Holds startup configuration file

RAM

Volatile

Holds runnning config, tables, queues etc


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


Router prompts

User EXEC mode

Privileged EXEC mode

Global Configuration mode

Specific Configuration modes

Router>

Router#

Router(config)#

Router(config-if)#and others


EXEC modes

You log in to User EXEC modeRouter>

You can give basic monitoring commands but cannot change the configuration

Enter enable to go to Privileged EXEC modeRouter#

Password may be used for security

You can give more commands and can go to configuration modes


Configuration modes

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

The prompt changes

This is global configuration mode

Additional commands take you to interface configuration, router configuration etc.


Leaving configuration modes

From interface configuration mode there are several ways of getting to privileged EXEC

Router(config-if)# exit Router(config)# exit Router#

Router(config-if)# endRouter#

Router(config-if)# Ctrl+zRouter#


Command Structure

Followed by <Enter>


? To get help

? Gives a list of commands available from the current prompt.

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

Start of command followed by ? with no space shows how the word can be continued.


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 whole word)

Router#s ru

% Ambiguous command: ‘s’


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

^

^


Keyboard shortcuts

Tab completes a partial command

Backspace erases to left of cursor

Ctrl+D erases at cursor (Delete does not)

Ctrl+Z returns from any config mode to privileged exec mode

Ctrl+C leave Setup mode


Show commands

Show ? To get a list

Many different show commands to give information about every aspect of the router and its operation

We use some of the most common.


General show commands

Show running-config shows the configuration 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 the configuration register, which controls how the router starts up.


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 one selected interface

You can shorten to show int s 0/0

Show ip interfaces gives IP statistics


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 command can delete the operating system. If you get an odd message about Flash – hands off – call for help.


Hostname

Router>enable

Router#config t

Router(config)#hostname Paris

Paris(config)#

Configure a suitable hostname so that you know which router you are managing and so that you can identify it in network documentation.


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


Vty password for Telnet

Paris(config)#line vty 0 4

Paris(config-line)#password cisco

Paris(config-line)#login

Paris(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


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 cisco

Not encrypted, used on older routers

If you configure both, then only the enable secret is used.


Message of the day

Paris(config)#banner motd # No unauthorised access #

# is a delimiter to show where the message starts and ends.

Any character can be used as long as it does not appear in the message.

The message should make it clear that unauthorised access is forbidden.


Reload

Shuts down the router and then starts it again.

If the configuration has changed then you are prompted to save it.

The running configuration in RAM is lost.

The startup configuration from NVRAM is (usually) loaded into RAM on startup.


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]


Back up as text file

Start text capture

Name file

show run

Stop text capture

Open saved file and


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.


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 default configuration. No passwords, no IP addresses etc.

Caution if you get this command wrong then you could erase something else, e.g. IOS


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 at once.

Save to NVRAM.


Restore text file

Go to global configuration mode

Hyperterminal Transfer menu

Send text file…

Or

Copy text from text file

“Paste to host” into Hyperterminal session


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 router is modular and on the bandwidth.

E.g. interface Ethernet 0 on an older router


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


Description

Paris(config)#interface fa0/0

Paris(config-if)#description Connects to Paris central switch

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


Switch interfaces

Switch physical interfaces do not have IP addresses

They are active by default and do not need the no shutdown command.

It can be useful to give them a description.


Switch IP address

The switch IP address goes on a virtual interface, not a real 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


Switch default gateway

SwA(config)#ip default gateway 172.16.255.254

Just like a workstation, a switch needs a default gateway if it exchanges messages with devices on a different network.

The default gateway is the address of the local router.


Interface – show commands

show interfaces states whether up or down, gives some protocol information and statistics about interface use.

show ip interface gives IP addresses and much more.

show ip interface brief gives summary of IP addresses and whether up/down. Very useful command.


Up or down

Interface status: Layer 1Up

Down

Administratively down (no shutdown to bring up)

Protocol: Layer 2Up

Down (no keepalive signal received)


Ping – step by step

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

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

Ping local hosts (checks own configuration and that of others)

Ping gateway

Ping other intermediate routers

Ping hosts on remote networks


Network baseline

Measure and record performanceAt 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


Find out about nodes

Ping – used from workstation, router or switch – shows if destination can be reached

Traceroute – shows hops along the path

Arp -a on workstation – shows list of MAC and IP addresses

show mac-address-table on switch – shows list of MAC addresses and switch ports


Summary Hierarchical Design model addresses performance,

scalability, maintainability & manageability issues.

Traffic Analysis is used to monitor network performance.

Hierarchical Design Model is composed of 3 layers:Access

Distribution

Core

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


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

Mod11

Technology

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