Ch.3 – Configuring a Router
CCNA 1 version 3.0
Rick Graziani
Cabrillo College
Note to instructors
• If you have downloaded this presentation from the Cisco Networking
Academy Community FTP Center, this may not be my latest version of
this PowerPoint.
• For the latest PowerPoints for all my CCNA, CCNP, and Wireless
classes, please go to my web site:
http://www.cabrillo.cc.ca.us/~rgraziani/
• The username is cisco and the password is perlman for all of
my materials.
• If you have any questions on any of my materials or the curriculum,
please feel free to email me at graziani@cabrillo.edu (I really don’t
mind helping.) Also, if you run across any typos or errors in my
presentations, please let me know.
• I will add “(Updated – date)” next to each presentation on my web site
that has been updated since these have been uploaded to the FTP
center.
Thanks! Rick
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Overview
Students completing this module should be able to:
• Name a router
• Set passwords
• Examine show commands
• Configure a serial interface
• Configure an Ethernet interface
• Execute changes to a router
• Save changes to a router
• Configure an interface description
• Configure a message-of-the-day banner
• Configure host tables
• Understand the importance of backups and documentation
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CLI command modes
Router#configure terminal
Router(config)#
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Configuring a router name
Mistake…
Should be…
Router#config t
Router(config)#hostname Tokyo
Tokyo(config)#
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Configuring router passwords
Not recommended, clear text
Encrypts the passwords
above, but…
Use this command instead, password is encryped
Router(config)#enable secret <password>
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service password-encryption command
WARNING
• service password-encryption uses a Cisco Level 7
encryption which is very easy to decrypt.
• For the GetPass! software www.boson.com
• However, the enable secret <password> uses a stronger
encryption method and cannot be easily hacked.
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enable secret <password> command
Doesn’t work for enable secret!
•
More later!
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Using exit, end and Control-Z
end
exit
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Using exit, end and Control-Z
Router>ena
Must be in privileged mode
Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#?
Configure commands:
aaa
Authentication, Authorization and Acc..
access-list
Add an access list entry
alias
Create command alias
appletalk
Appletalk global configuration commands
arap
Appletalk Remote Access Protocol
arp
Set a static ARP entry
<text omitted>
Router(config)#exit
00:03:20: %SYS-5-CONFIG_I: Configured from console by con
Router#
Router(config)#interface interface
Router(config-if)#exit
Router(config)#router routing-protocol
Router(config-router)#exit
Router(config)#exit
Router#
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Message each time you exit “global
configuration mode”
10
Using exit, end and Control-Z
Router# conf t
(abbreviated)
Router(config)# router protocol
Router(config-router)# (commands)
Router(config-router)# exit
Router(config)# exit
Router#
Router(config)# interface type port
Router(config-if)# (commands)
Router(config-if)# end
(or Control-Z)
Router#
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Examining the show commands
•
•
•
•
•
•
•
•
•
•
•
•
show interfaces – Displays all the statistics for all the interfaces on the
router. To view the statistics for a specific interface, enter the show
interfaces command followed by the specific interface and port number.
show controllers serial – Displays information-specific to the interface
hardware
show clock – Shows the time set in the router
show hosts – Displays a cached list of host names and addresses
show users – Displays all users who are connected to the router
show history – Displays a history of commands that have been entered
show flash – Displays information about flash memory and 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 specific status of any
configured Layer 3 protocols
show startup-configuration – Displays the saved configuration located
in NVRAM
show running-configuration – Displays the configuration currently
running in RAM
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show interfaces <interface> command
MAC Address
Router>show interface ethernet 0
Status
Ethernet0 is administratively down, line protocol is down , using hub 0
Hardware is Lance, address is 0010.7b3a.cf84 (bia 0010.7b3a.cf84)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
Routing
metric
ARP link
type: ARPA, ARP Timeout 04:00:00 ARP cache entries timer
Data
information
Last input never, output 01:05:35, output hang never
encapsulation
(later)
(Ethernet-II)
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 input packets with dribble condition detected
63 packets output, 11676 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Router>
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Where is the MAC Address?
Router>show interface serial 0
Serial0 is administratively down, line protocol is down
Hardware is HD64570
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
28 packets output, 9576 bytes, 0 underruns
0 output errors, 0 collisions, 17 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=down DSR=down DTR=down RTS=down CTS=down
Router>
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Examining the show commands
•
We will log into a router a examine some of the show
commands.
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Configuring a serial interface
Configuring an IP Address on an interface…
Router(config)#interface serial 0/0
Router(config-if)#ip address <ip address> <netmask>
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show ip interface command
Router# show ip interface brief
Interface
Ethernet0
Serial0
IP-Address
131.108.1.11
198.135.2.49
OK?
YES
YES
Method
manual
manual
Status
up
administratively down
Protocol
up
down
What is wrong here? The administrator has either done a
“shutdown” on the interface or has forgotten to do a “no shutdown”.
•
•
A serial interface will not show “up” and “up” unless both
ends are properly configured (mostly) and a the no
shutdown command is used.
If one router’s configuration looks okay, check the other
router’s configuration.
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Configuring a serial interface
Lab
Real world
• On serial links that are directly interconnected, as in a lab environment,
•
one side must be considered a DCE and provide a clocking signal.
The clock is enabled and speed is specified with the clock rate
command.
Router(config)#interface serial 0/0
Router(config-if)#clock rate 56000
Router(config-if)#no shutdown
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Configuring a serial interface
RouterA
DTE cable
RouterB
DCE cable
RouterB(config)#inter serial 1
RouterB(config-if)#clock rate ?
Speed (bits per second)
1200
2400
4800
9600
19200
38400
56000
64000
<text omitted>
2000000
4000000
<300-4000000>
Choose clockrate from list above
RouterB(config-if)#clock rate 64000
RouterB(config-if)#
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Configuring a serial interface
DTE Cable
DCE Cable
How can you tell which end is the DTE and which end is the DCE?
 Look at the label on the cable.
 Look at the connecter between the two cables - The DTE cable will
always be male and the DCE cable will always be female.
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Configuring a serial interface
RouterA
DTE cable
RouterB
DCE cable
RouterA#show controllers serial 0
HD unit 0, idb = 0xECA4C, driver structure at 0xF1EC8
buffer size 1524 HD unit 0, V.35 DTE cable
cpb = 0x62, eda = 0x403C, cda = 0x4050
RX ring with 16 entries at 0x624000
00 bd_ptr=0x4000 pak=0x0F5704 ds=0x62FFB8 status=80 pak_size=22
This is one of few commands where there must be a space between the interface type and the port.
RouterB#show controllers serial 0
buffer size 1524 HD unit 0, V.35 DCE cable, clockrate 64000
cpb = 0x62, eda = 0x408C, cda = 0x40A0
RX ring with 16 entries at 0x624000
00 bd_ptr=0x4000 pak=0x0F2F04 ds=0x627908 status=80 pak_size=22
How can you tell which end is the DTE and which end is the DCE?
 Use the show controllers command!
 It will also tell you the type of cable, in our labs we will be using a V.35
cable.
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Configuring a serial interface
This end up!
(The wider end is up.)
• Please be very careful when connecting the male and female
•
•
•
V.35 cables together AND when connecting the serial cable to
the router!
They only connect ONE WAY!
Be sure the two ends match!
Don’t force it!
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Executing adds, moves, and changes
running-config
IOS (running)
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startup-config
IOS
Bootup program
ios (partial)
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Executing adds, moves, and changes
Router#show startup-config
%% Non-volatile configuration memory is not present
No startup-config
file in NVRAM
Router#show running-config
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
ip subnet-zero
!
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0
no ip address
no ip directed-broadcast
shutdown
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Default running-config
file, created in RAM
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Executing adds, moves, and changes
Router#show running-config
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
ip subnet-zero
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
•
•
The running-config
The configuration file contains global, process, and interface information that directly affects the
operation of the router and its interface ports.
All changes to the router are made to the running-config file and take affect immediately on the
router (with just a couple of exceptions).
–
–
–
–
IP address
Routing Protocols
Router’s Name
etc.
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copy running-config startup-config
During bootup
running-config
RAM
startup-config
Router# copy running-config startup-config
•
•
•
Changes to the router are automatically put in the running-config file.
If the router loses power or reboots, everything in RAM is lost including the runningconfig file.
To make sure the changes to the router’s configuration remain saved, you must copy
the running-config from RAM into the startup-config into NVRAM:
Router# copy
running-config
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startup-config
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copy running-config startup-config
Router#copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
Router#show startup-config
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
!
ip subnet-zero
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
!
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The startup-config file now
identical to running-config
and the router will also have
these changes if the router
reboots.
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copy running-config startup-config
Router# copy running-config startup-config
Or
Router# copy running startup
OR
Router# copy run start
OR
Any usage of the command or parameters, so that they are still uniquely recognizable.
WARNING
• Using an incorrect configuration file name could overwrite the router’s IOS in flash, as the router believes
you are trying to copy a blank file into flash.
Router#copy running-config start-up
**** NOTICE ****
Incorrect file name!
Flash load helper v1.0
This process will accept the copy options and then terminate
the current system image to use the ROM based image for the copy.
Routing functionality will not be available during that time.
If you are logged in via telnet, this connection will terminate.
Users with console access can see the results of the copy operation.
---- ******** ---Proceed? [confirm]^C
%Copy cancelled by user request.
Press <control> C
Router#
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copy running-config startup-config
Router# copy running-config startup-config
Or
Router# copy running startup
OR
Router# copy run start
OR
Any usage of the command or parameters, so that they are still uniquely recognizable.
WARNING
• This is also incorrect, and will overwrite the startup-config with a blank file.
Router#copy runningconfig startup-config
Destination filename [startup-config]?
?Bad filename
Router#
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Incorrect file name!
Press <control> C
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Displaying the config files
show running-config
show startup-config
1
These commands can only be done in privilege mode
because they display password information.
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Executing adds, moves, and changes
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Configuring Interfaces
Router(config-if)#exit
Router(config)#interface serial 0
Router(config-if)#ip add 172.16.10.1 255.255.255.0
Router(config-if)#clock rate 64000
(only if DCE)
Router(config-if)#no shutdown
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Finishing the Configuration
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Importance of configuration standards
•
•
•
In order to manage a network, there must be a centralized
support standard.
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 of unplanned downtime,
and exposure to events that may have an impact on
network performance.
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Interface descriptions
RouterB#show inter e 0
Serial0 is up, line protocol is up
Hardware is HD64570
Description: Engineering LAN, Bldg. 18
Internet address is 10.1.1.1/24
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Interface descriptions
Gateway(config)#inter e 0
Gateway(config-if)#description LAN interface for Marketing
Gateway(config-if)#end
Gateway#
Gateway#show run
Building configuration...
<text omitted>
!
interface Ethernet0
description LAN interface for Marketing
no ip address
no ip directed-broadcast
shutdown
<text omitted>
Gateway#show interface ethernet 0
Ethernet0 is administratively down, line protocol is down
Hardware is Lance, address is 0000.0c34.9ebb (bia 0000.0c34.9ebb)
Description: LAN interface for Marketing
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 252/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
<text omitted>
Gateway#copy run start
Don’t forget this or next time router
Destination filename [startup-config]?
reboots these changes will be lost!
Building configuration...
Gateway#
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Configuring interface description
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Login banners and Configuring messageof-the-day (MOTD)
Wording is not
the same, but
you get the idea.
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Login banners and Configuring messageof-the-day (MOTD)
Router(config)#hostname Gateway
Gateway(config)#
MOTD
Gateway(config)#banner motd #
Enter TEXT message. End with the character '#'.
Warning!
Stay away! #
Gateway(config)#end
Gateway#exit
Press RETURN to get started.
Prompt changes
(Message Of The Day)
Warning!
Stay away!
User Access Verification
Password:
Gateway#show run
Building configuration...
<text omitted>
!
hostname Gateway
!
<text omitted>
!
banner motd ^C
Warning!
Stay away! ^C
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Delimiter always shows as “^C”
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Host name resolution
Router# ping 172.16.32.1
Router# ping Auckland
Router# telnet 192.168.53.1
Router# telnet Beirut
Router# traceroute 192.168.89.1
Router# traceroute Capetown
•
•
•
The Cisco IOS software maintains a cache of host name-to-address mappings
for use by EXEC commands.
This cache speeds up the process of converting names to addresses.
Host names, unlike DNS names, are significant only on the router on which
they are configured. (DNS is also an option – later)
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Host name resolution
Configuring Multiple IP Addresses
Router(config)# ip host SantaCruz 172.16.32.1 192.168.53.1
• This does not make the router a DNS (Domain Name Server).
• This command does not turn your router into a DNS server.
• This command does not effect packets entering your router to be
•
•
•
routed.
This only affects the IOS commands entered at the router prompt.
Multiple ip addresses can be entered in case one interface is down.
It is usually a good idea to use the same list of names on all your router
configs.
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Configuring host tables
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Router(config)# ip domain-lookup
Router#wreh
Translating "wreh"...domain server (255.255.255.255) (Takes a few seconds)
Translating "wreh"...domain server (255.255.255.255) (Takes a few seconds)
Router(config)# no ip domain-lookup
Router#wreh
Translating "wreh"
% Unknown command or computer name, or unable to find computer address
•
•
•
If you are not using the services of a DNS server, it is best to disable this process.
DNS (Domain Name Service) is enabled by default with a server address of
255.255.255.255, which is a local broadcast.
If enabled, with no DNS server on the network, may cause a slight, but irritable
delay when making typing mistakes.
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Configuration backup and documentation
• Configuration files should be stored as backup files in the
•
event of a problem.
Configuration files can be stored on a network server, on a
TFTP server, or on a disk stored in a safe place.
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Copying, editing, and pasting configurations
• A TFTP server will allow image and configuration uploads and
•
downloads over the network.
The TFTP server can be another router, or it can be a host system.
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Copying, editing, and pasting configurations
• The TFTP host can be any system that has TFTP software loaded and
operating and able to receive files from the TCP/IP network.
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Copying, editing, and pasting configurations
running-config
RAM
IOS (running)
startup-config
IOS
copy flash tftp
copy tftp flash
copy startup-config tftp
copy tftp startup-config
copy running-config tftp
copy tftp running-config
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Copying, editing, and pasting configurations
• Troubleshooting: Be sure you can ping the TFTP server.
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TFTP Software and Servers
Router# copy flash tftp
•
•
•
When using Windows, the TFTP server software must be running.
The copy can be performed from the console port or from a telnet session.
The telnet session can be performed on the same computer where the TFTP
server is running (or to a different computer).
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TFTP Software and Servers
•
TFTP software either comes free with the OS (Linux/Unix) or can be
downloaded for free.
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TFTP Software and Servers
• Just double click on the shortcut…
• Remember, TFTP is “Trivial” FTP:
–
–
–
–
No authentication
No login
No choice for directory
Uses UDP and verified via a TFTP checksum (not TCP ACKs)
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Summary (1/2)
The router has several modes:
• User EXEC mode
• Privileged EXEC mode
• Global configuration mode
• Other configuration modes
The command-line interface may be used to make changes
to the configuration:
• Setting the hostname
• Setting passwords
• Configuring interfaces
• Modifying configurations
• Showing configurations
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Summary (2/2)
An understanding of the following key points should have
been achieved:
• Configuration standards are key elements in the success of
any organization maintaining an efficient network.
• Interface descriptions can include important information to
help network administrators understand and troubleshoot
their networks.
• Login banners and messages-of-the-day provide users
with information upon login to the router.
• Host name resolutions translate names to IP addresses to
allow the router to quickly convert names to addresses.
• Configuration backup and documentation is extremely
important to keep a network operating smoothly.
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