Ccna2 mod3-configuring a-router

Ch.3 – Configuring a Router

CCNA 1 version 3.0

Rick Graziani

Cabrillo College

Rick Graziani [email protected] 2

Note to instructors

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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 [email protected] (I really don’t mind helping.) Also, if you run across any typos or errors in my presentations, please let me know.

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Thanks! Rick


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


CLI command modes

Router#configure terminalRouter(config)#


Configuring a router name

Router#config t

Router(config)#hostname Tokyo

Tokyo(config)#

Mistake…

Should be…


Configuring router passwords

Not recommended, clear text

Router(config)#enable secret <password>Use this command instead, password is encryped

Encrypts the passwords above, but…


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.

service password-encryption command


Doesn’t work for enable secret!

• More later!

enable secret <password> command


exit

end

Using exit, end and Control-Z


Router>enaRouter#configure terminalEnter 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)#exit00:03:20: %SYS-5-CONFIG_I: Configured from console by conRouter#

Router(config)#interface interfaceRouter(config-if)#exitRouter(config)#router routing-protocolRouter(config-router)#exitRouter(config)#exitRouter#

Message each time you exit “global configuration mode”

Must be in privileged mode



Router# conf t (abbreviated)

Router(config)# router protocolRouter(config-router)# (commands)Router(config-router)# exitRouter(config)# exitRouter#

Router(config)# interface type portRouter(config-if)# (commands)Router(config-if)# end (or Control-Z)Router#



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


Router>show interface ethernet 0Ethernet0 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) ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output 01:05:35, 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 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 outRouter>

Status MAC Address

Routing metric information (later)

Data link encapsulation

(Ethernet-II)

ARP cache entries timer

show interfaces <interface> command


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>


Examining the show commands

• We will log into a router a examine some of the show commands.


Configuring a serial interface

Router(config)#interface serial 0/0

Router(config-if)#ip address <ip address> <netmask>

Configuring an IP Address on an interface…


show ip interface command

• 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.

Router# show ip interface brief

Interface IP-Address OK? Method Status Protocol

Ethernet0 131.108.1.11 YES manual up up

Serial0 198.135.2.49 YES manual administratively down down

What is wrong here? The administrator has either done a “shutdown” on the interface or has forgotten to do a “no shutdown”.


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



RouterB(config)#inter serial 1RouterB(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 64000RouterB(config-if)#

RouterB DCE cable

RouterA DTE 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.

DTE Cable DCE Cable



RouterA#show controllers serial 0HD unit 0, idb = 0xECA4C, driver structure at 0xF1EC8buffer size 1524 HD unit 0, V.35 DTE cablecpb = 0x62, eda = 0x403C, cda = 0x4050RX ring with 16 entries at 0x62400000 bd_ptr=0x4000 pak=0x0F5704 ds=0x62FFB8 status=80 pak_size=22

RouterB#show controllers serial 0buffer size 1524 HD unit 0, V.35 DCE cable, clockrate 64000cpb = 0x62, eda = 0x408C, cda = 0x40A0RX ring with 16 entries at 0x62400000 bd_ptr=0x4000 pak=0x0F2F04 ds=0x627908 status=80 pak_size=22

RouterB DCE cable

RouterA DTE cable

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.

This is one of few commands where there must be a space between the interface type and the port.



• 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!

This end up!

(The wider end is up.)



running-config

IOS (running)

startup-config IOS

ios (partial)Bootup program

Executing adds, moves, and changes


Router#show startup-config%% Non-volatile configuration memory is not present

Router#show running-configBuilding configuration...

Current configuration:!version 12.0service timestamps debug uptimeservice timestamps log uptimeno 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

No startup-config file in NVRAM

Default running-config file, created in RAM



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.

Router#show running-configBuilding configuration...Current configuration:!version 12.0service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname Router!ip subnet-zero!interface Ethernet0 no ip address no ip directed-broadcast shutdown



startup-config

RAMrunning-config

During bootup

• 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 running-

config 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 startup-config


copy running-config startup-config


Router#copy running-config startup-configDestination filename [startup-config]?Building configuration...

Router#show startup-config!version 12.0service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname Router!!ip subnet-zero!interface Ethernet0 no ip address no ip directed-broadcast shutdown!

The startup-config file now identical to running-config and the router will also have these changes if the router reboots.



Router# copy running-config startup-config OrRouter# copy running startup ORRouter# copy run start ORAny 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 ****Flash load helper v1.0This process will accept the copy options and then terminatethe 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.Router#

Incorrect file name!

Press <control> C




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#

Incorrect file name!Press <control> C



show startup-config

show running-config

These commands can only be done in privilege mode because they display password information.

1

Displaying the config files




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


Finishing the Configuration


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.


Interface descriptions

RouterB#show inter e 0Serial0 is up, line protocol is up Hardware is HD64570 Description: Engineering LAN, Bldg. 18 Internet address is 10.1.1.1/24


Gateway(config)#inter e 0Gateway(config-if)#description LAN interface for MarketingGateway(config-if)#endGateway#Gateway#show runBuilding configuration...<text omitted>!interface Ethernet0 description LAN interface for Marketing no ip address no ip directed-broadcast shutdown<text omitted>

Gateway#show interface ethernet 0Ethernet0 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 startDestination filename [startup-config]?Building configuration...Gateway#

Don’t forget this or next time router reboots these changes will be lost!

Interface descriptions


Configuring interface description


Login banners and Configuring message-of-the-day (MOTD)

Wording is not the same, but you get the idea.


Router(config)#hostname GatewayGateway(config)#Gateway(config)#banner motd #Enter TEXT message. End with the character '#'.Warning!Stay away! #Gateway(config)#endGateway#exitPress RETURN to get started.

Warning!Stay away!

User Access Verification

Password:Gateway#show runBuilding configuration...<text omitted>!hostname Gateway!<text omitted>!banner motd ^CWarning!Stay away! ^C

Delimiter always shows as “^C”

MOTD (Message Of The Day)

Prompt changes

Login banners and Configuring message-of-the-day (MOTD)


Host name resolution

Router# ping 172.16.32.1Router# ping Auckland

Router# telnet 192.168.53.1Router# telnet Beirut

Router# traceroute 192.168.89.1Router# 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)


Host name resolution

• 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.

Router(config)# ip host SantaCruz 172.16.32.1 192.168.53.1

Configuring Multiple IP Addresses


Configuring host tables


• 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.

Router(config)# ip domain-lookupRouter#wrehTranslating "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-lookupRouter#wreh Translating "wreh"% Unknown command or computer name, or unable to find computer address


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.


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.


• The TFTP host can be any system that has TFTP software loaded and operating and able to receive files from the TCP/IP network.



RAMIOS (running)running-config startup-config IOS

copy startup-config tftp

copy tftp startup-config

copy running-config tftp

copy tftp running-config

copy flash tftp

copy tftp flash




• Troubleshooting: Be sure you can ping the TFTP server.


• 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).

Router# copy flash tftp

TFTP Software and Servers


• TFTP software either comes free with the OS (Linux/Unix) or can be downloaded for free.



• 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)

Cisco TFTP Server.lnk



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


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.

Documents

Ccna2 mod3-configuring a-router