CCNA2 M3 Configuring a Router

8/14/2019 CCNA2 M3 Configuring a Router

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CCNA Semester2

Module 3

Configuring a Router

Objectives

Basic router configuration The importance of backups and documentation


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Configuring a Router

CLI Command Modes


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Global Configuration Modes

Password Configuration

enable secretcommand, which is encrypted, is prefered and overide enable password


4/15

Configuring an interface

Interfaces status

Router interfaces have 2 status indications:

interface (up/down) and line protocol (up/down),

the links only work if both are up.

By default, router interfaces are shutdown and

the status is: interface is administratively down,

line protocol is down


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Configuring serial link

One side must be considered a DCE and provide

a clocking signal

Router(config-if)#clock rate

On Cisco router, HDLC is the default encapsulation on

serial link

Router(config-if)#encapsulation

By default, serial interface is ofDTE device, shutdown

and have no ip address

Configure router hostname:

Router(config)#hostname Center

Center(config)#

FlashNVRAMRAM

Internetwork Operating System

ProgramsActive

ConfigurationFile

Tablesand

Buffers

BackupConfiguration

File

OperatingSystems

Interfa

ces

Router#show version Router#show flash

Router#show interfaces

Router#show processes CPU

Router#show protocols

Router#show running-config

Or Router#write term

Router#show mem

Router#show stacks

Router#show buffers

Router#show startup-config

Or Router#show config

Router Commands: Show


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Examining the show Commands

There are many show commands that you can use to

examine the contents of files in the router and for

troubleshooting.

In both privileged EXEC and user EXEC modes, thecommand show ? provides a list of available show

commands.

Show commands

show interfaces Displays all the statistics for all theinterfaces on the router orshow interfaces serial 0/1

show controllers serial Displays information-specific tothe interface hardware

show clock Shows the time set in the router

show hosts Displays a cached list of host names andaddresses

show users Displays all users who are connected to therouter

show history Displays a history of commands that havebeen entered


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Show commands

show flash Displays information about flash memoryand what IOS files are stored there

show version Displays information about the router and

the IOS that is running in RAM show ARP Displays the ARP table of the router

show protocol Displays the global and interface specificstatus of any configured Layer 3 protocols

show startup-configuration Displays the savedconfiguration located in NVRAM

show running-configuration Displays the configurationcurrently running in RAM

Back to default configuration

Running configuration file can never be erased

but you can bring router to default configuration

erasing startup-config file and restart router:

erase startup-config

reload

Save configurations changes (yes/no)? no


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Finishing the Configuration

Configuration Standards

A standard is a set of rules orprocedures that are

either widely used or officially specified.

Configuration, security, performance, and other

issues must be adequately addressed for the

network to function smoothly.

Creating standards for network consistency helps

reduce network complexity, the amount ofunplanned downtime, and exposure to events that

may have an impact on network performance.


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Description and Banner

An interface description should be used to notify important information such as a

distant router, a circuit number, or a specific network segment.

A login banner is a message that is displayed at login and is useful for conveying

messages that affect all network users, such as notices of impending system

shutdowns.

Host Name Resolution

Host name resolution is the process that a computer

system uses to associate a host name with an IP address.

Host names, unlike DNS names, are significant only on the

router on which they are configured.


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ip domain-lookup command

Router (config)#

ip domain-lookupip domain-lookup

Enables the use of DNS

Enable by default

show hosts EXEC command

show hostsshow hosts

Router#

display a cached list of HOST table.

show hosts command Description

Host Host name learnt

Flag Status of this host name entry

permanent (perm) Permanent entry as entered by administrator into router configuration

temporary (temp) Host name entry learnt by DNS server (removed after 72 hours of inactivity)

OK Entry is valid

EX Entry is expired

?? Not sure about this entry, need to re-validate

Age Time interval (in hours) router last referred to this entry

Address(es) Layer 3 address(es) associated with hostname

Type Protocol field (IP, HP-IP)


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HOST Table

Loopback Interface

Router (config)#

interface loopback loopback_interface_numberinterface loopback loopback_interface_number

A virtual interface that is always up and allows

sessions (BGP, RSRB) to stay up even if the out-

bound interface is down

Packets routed to the loopback interface are

rerouted back to the router or access server and

processed locally.

Use loopback interface to simulate an active

interface


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Configuration backup and documentation

Management of device configuration includes the

following tasks: Listing and comparing configuration files on running devices

Storage of configuration files on network servers

Performing software installations and upgrades

Configuration File with TFTP server


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Configuration File with Hyper Terminal

Use terminal length 0 to display all the output from commands atonce

Start Capture text

Show running-config Stop Capture text

Summary

Router name, description, banner, hosts..

Configure router interface

Router show commands

Backup configuration files


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Lab Topology

Lab_A

Lab_B

Lab_C

S0/0

S0/1

S0/0

F0/0

S0/1

F0/0

Lab_D

Lab_E

Lab_F

S0/0

S0/1

S0/0

F0/0

S0/1

F0/0

F0/0 F0/0

S0/1S0/0

Port Lab_A Lab_B Lab_C Lab_D Lab_E Lab_F

S0/0 201.10.11.1/24 199.6.13.1/24 204.204.7.1/24 192.168.3.1/24

204.204.7.2/24

172.17.13.1/16

34.10.120.1/16 N/A

S0/1 N/A 201.10.11.2/24 199.6.13.2/24 192.168.3.2/24 34.10.210.5/16

F0/0 172.16.11.1/16 172.18.12.1/24 172.16.11.2/16 172.18.12.2/24 172.17.13.2/16

CCNA2 Module3

Documents

CCNA2 M3 Configuring a Router