Introduction to Routers.ppt

7/25/2019 Introduction to Routers.ppt

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1Version 3.1

Module 2Introduction to Routers


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2Version 3.1

Cisco IOS Software

As with a computer, a router or switch cannot

function without an operating system.

The Cisco Internetwork Operating System (IOS)

Also now used in the Catalyst switches IOS provides

!asic routing " switching #unctions

Access to networked resources

$etwork scala%ility


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3Version 3.1

Accessing the Command Line Interface

The command line interface (CLI) is accessed

through a console session.

A console uses a low speed serial connection

directly from a computer or terminal to the consoleconnection on the router.


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4Version 3.1

Router Configuration Modes

The Cisco CLI uses a hierarchical structure.

This structure requires entry into dierent modesto accomplish particular tas!s.

"ach con#guration mode is indicated with adistincti$e prompt and allows only commands thatare appropriate for that mode.


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5Version 3.1

Router Configuration Modes

The I%& pro$ides a command interpreter ser$ice!nown as the command e'ecuti$e (""C).

After each command is entered, the ""C$alidates and e'ecutes the command.

As a security feature the Cisco I%& softwareseparates the ""C sessions into two accessle$els.

These le$els are user ""C mode and pri$ileged

""C mode.


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6Version 3.1

ser !"!C Mode

The user ""C mode allows only a limited numerof asic monitoring commands.

This is often referred to as a $iew only mode.

The user ""C le$el does not allow any commands

that might change the con#guration of the router.

The user ""C mode can e identi#ed y the >

prompt.


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#ri$ileged !"!C Mode

The pri$ileged ""C mode pro$ides access to allrouter commands.

This mode can e con#gured to require a

password.

Con#guration and management commands requirethat the networ! administrator e at the pri$ileged

""C le$el.

*loal con#guration mode and all other more

speci#c con#guration modes can only e reached

from the pri$ileged ""C mode.

The pri$ileged ""C mode can e identi#ed y the

#prompt.


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#ri$ileged !"!C Mode

To access the pri$ileged ""C le$el from the user""C le$el, enter the enablecommand at the >

prompt.

If a password is con#gured, the router will then

as! for that password. +or security reasons, a Cisco networ! de$ice will

not show the password that is entered.

hen the correct password is entered, the router

prompt will change to #.


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Version 3.1

IOS software and features

Cisco continues to de$elop dierent I%& software

images to optimi-e the Cisco I%& software that

these $arious platforms require. "ach image

represents a dierent feature set that ser$es the

$arious de$ice platforms, a$ailale memory

resources, and customer needs.

&se the Cisco So#tware Advisorto o%tain current Cisco

IOS so#tware in#ormation'
http://www.cisco.com/cgi-bin/Support/CompNav/Index.plhttp://www.cisco.com/cgi-bin/Support/CompNav/Index.pl


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The naming con$ention for the dierent Cisco I%&

releases contains three parts

/ The platform on which the image runs

/The special features supported in the image/ here the image runs and whether it has een

-ipped or compressed


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%ne of the main considerations when selecting a

new I%& image is compatiility with the router

0ash and 1A2 memory.

3se the show versioncommand on the Ciscode$ice to chec! the current image and a$ailale

0ash.


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IOS $ersion

%oot ROM$ersion

Router u&time

Last restartmethod

S'stem image file( location

Configurationregister setting

)um*er ( t'&e ofinterfaces on the

router

#latform

+eature set

Location to *eused for loadingthe IOS


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,his command will show all of the CiscoIOS image files not ust the one that therouter %ooted #rom'

ight compare to a directory listing


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,hree O&erating !n$ironments

The 1%2 monitor performs the ootstrap processand pro$ides low4le$el functionality and

diagnostics. It is used to reco$er from system

failures and to reco$er a lost password.

It can only e accessed y way of a direct, physical

connection through the console port.

hen the router is running in oot 1%2 mode,

only a limited suset of the Cisco I%& feature set

is a$ailale.


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15Version 3.1

!ootstrap loader in RO

e*ecutes

Step +

Step , Operating system loads

Step - .ardware check

The con#iguration #ile is loaded i#

one is #ound in $/RAStep 0

Step 1$o con#iguration is in $/RA2 it

looks #or T3T4 server2 then

S5T&4 #rom console

A Router Starts &hen a Cisco router powers up, it performs a power4on

self test (5%&T).


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16Version 3.1

Ste&s in Router Initiali-ation

-

+

,

-

+

,


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17Version 3.1

Setu& Mode

&etup mode is not intended to e used to entercomple' protocol features in a router.

The purpose of the setup mode is to permitadministrators to install a asic con#guration for

routers when a con#guration cannot e otainedfrom another source.

In the setup mode, default answers appear insquare rac!ets [ ]following the question.

5ress the Enter!ey to use these defaults.

6uring the setup process, Ctrl-Ccan e pressed atany time to terminate the process.


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18Version 3.1

Setu& Mode

The router will enter setup mode when6

The contents o# $/RA have %een erased with the

7erase start8 command

9hen the router is 7out o# the %o*8 and has not %een

initially con#igured

A#ter deleting the %ackup con#iguration and reloading

the router

:ou can make the router enter setup mode %y entering6

Router;setup


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19Version 3.1

nderstanding L! indicators on therouter

This green light means that the system is on and has

initiali


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20Version 3.1

Items )eeded to Initiall'Configure a Router

%/0/to/R/ on

the #C serial &ort

Rollo$er ca*le

RouterConsole&ort


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21Version 3.1

,wo Le$els of Access

To enter commands and con#gure a Cisco router, auser must log into the router to access the userinterface.

+or security purposes, a Cisco router has two le$els

of access.


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22Version 3.1

,wo Le$els of Access

To enter pri$ileged ""C mode, type enableat the>prompt.

If a password has een set, enter it at thepassword:prompt.

Two commands can e used to set a passwordused to access pri$ileged ""C mode

- enable password password

- enable secret password

If both commands are used, the enablesecretcommand takes precedence.


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23Version 3.1

Logging into the router

Once into the privileged 5=5C mode2 it %ecomes the 7umpingo## place to go to other con#iguration modes6

Router>ena%le

4assword6 ******

Router;con#igure terminalRouter(con#ig);inter#ace serial ?

Router(con#ig@i#);e*it

Router(con#ig);line con ?

Router(con#ig@line);login

Router(con#ig@line);e*it

Router(con#ig);e*it

Router;disa%le

Router>

Ctrl-Zor endmay

%e used at any time to

return to privileged

mode #rom anywhere


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24Version 3.1

RO,!R MO!S

Router > &ser mode

Router ; 4rivileged mode

Router(con#ig); lo%al con#iguration mode

3rom the glo%al con#iguration mode2 you can enter speci#ic

con#iguration modes

Router(con#ig@i#); Inter#ace con#iguration mode

Router(con#ig@line); Bine con#iguration mode

Router(con#ig@router); Router con#iguration mode


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25Version 3.1

sing the 4el& S'stem

?shows availa%le commands #or a particular mode

There are di##erent commands #or user and privileged2 and

even di##erent commands #or glo%al mode'

show?9ould give a list o# show commands

s?would give all commands that %egin with the letter 7S8

I# you cant remem%er the command %ut know what it

starts with2 use the ?a#ter the #irst letter or two'


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27Version 3.1


The --More--prompt indicates that there aremultiple screens of output.

hen a --More--prompt appears, press theSpacebarto $iew the ne't a$ailale screen.

To display 7ust the ne't line, press the ReturnorEnter!ey.

5ress any other !ey to return to the prompt.


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29Version 3.1

!diting Commands

5Ctrl65A6 Mo$e to *eginning of line

5Ctrl65!6 Mo$e to the end of the line

5!sc65%6 Mo$e *ac7 one word

5Ctrl65+6 Mo$e forward one character

5Ctrl65%6 Mo$e *ac7 on character

5!sc65+6 Mo$e forward one word

8 Sign means that the line has scrolled to the left

To disable enhanced editin mode, t!peterminal no editingat the pri"ileed E#EC

mode prompt.


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Router Command 4istor'

Ma9imum num*er of commands in the histor'*uffer is 2:

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Introduction to Routers.ppt