Ch.3 – Configuring a Router CCNA 1 version 3.0 Rick Graziani Cabrillo College
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OverviewStudents 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
Configuring a router nameMistake…Should be…Router#config tRouter(config)#hostname TokyoTokyo(config)#
Configuring router passwords Not recommended, clear text Encrypts the passwords above, but… Use this command instead, password is encryped Router(config)#enable secret <password>
service password-encryption commandWARNING• 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.
enable secret <password> command Doesn’t work for enable secret!• More later!
Using exit, end and Control-ZRouter>enaRouter#configure terminal Must be in privileged modeEnter 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# Message each time you exit “globalRouter(config)#interface interface configuration mode” Router(config-if)#exit Router(config)#router routing-protocol Router(config-router)#exit Router(config)#exit Router#
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#
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
show interfaces <interface> command Router>show interface ethernet 0 Status MAC Address 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 ARP type: ARPA, ARP Timeout 04:00:00 ARP cache entries timer Data link metricencapsulation Last input never, output 01:05:35, output hang never information (Ethernet-II) Last clearing of "show interface" counters never (later) 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>
Where is the MAC Address?Router>show interface serial 0Serial0 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=downRouter>
Examining the show commands• We will log into a router a examine some of the show commands.
Configuring a serial interfaceConfiguring an IP Address on an interface…Router(config)#interface serial 0/0Router(config-if)#ip address <ip address> <netmask>
show ip interface commandRouter# show ip interface briefInterface IP-Address OK? Method Status ProtocolEthernet0 188.8.131.52 YES manual up upSerial0 184.108.40.206 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”.• 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.
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 0/0Router(config-if)#clock rate 56000Router(config-if)#no shutdown
Configuring a serial interface RouterA RouterB DTE cable 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)#
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.
Configuring a serial interface RouterA RouterB DTE cable 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=22How 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.
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!
Executing adds, moves, and changesRouter#show startup-config%% Non-volatile configuration memory is not present No startup-config file in NVRAMRouter#show running-configBuilding configuration...Current configuration:!version 12.0service timestamps debug uptime Default running-configservice timestamps log uptime file, created in RAMno 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
Executing adds, moves, and changesRouter#show running-configBuilding configuration...Current configuration:!version 12.0service timestamps debug uptime The running-configservice timestamps log uptimeno service password-encryption!hostname Router!ip subnet-zero!interface Ethernet0 no ip address no ip directed-broadcast shutdown• 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.
copy running-config startup-config During bootup running-config RAM startup-configRouter# 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 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-config Destination filename [startup-config]? Building configuration... Router#show startup-config ! The startup-config file now version 12.0 identical to running-config service timestamps debug uptime and the router will also have service timestamps log uptime these changes if the router no service password-encryption reboots. ! hostname Router ! ! ip subnet-zero ! interface Ethernet0 no ip address no ip directed-broadcast shutdown !
copy running-config startup-configRouter# 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 **** Incorrect file name!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# Press <control> C
copy running-config startup-configRouter# 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• This is also incorrect, and will overwrite the startup-config with a blank file.Router#copy runningconfig startup-config Incorrect file name!Destination filename [startup-config]? Press <control> C?Bad filenameRouter#
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.
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 descriptionsRouterB#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
Interface descriptionsGateway(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 start Don’t forget this or next time routerDestination filename [startup-config]? reboots these changes will be lost!Building configuration...Gateway#
Login banners and Configuring message-of-the-day (MOTD) Wording is not the same, but you get the idea.
Login banners and Configuring message-of-the-day (MOTD)Router(config)#hostname Gateway Prompt changesGateway(config)#Gateway(config)#banner motd # MOTD (Message Of The Day)Enter TEXT message. End with the character #.Warning!Stay away! #Gateway(config)#endGateway#exitPress RETURN to get started.Warning!Stay away!User Access VerificationPassword:Gateway#show runBuilding configuration...<text omitted>!hostname Gateway!<text omitted>!banner motd ^C Delimiter always shows as “^C”Warning!Stay away! ^C
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)
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.
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.
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.
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.
Copying, editing, and pasting configurations• Troubleshooting: Be sure you can ping the TFTP server.
TFTP Software and ServersRouter# 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).
TFTP Software and Servers • TFTP software either comes free with the OS (Linux/Unix) or can be downloaded for free.
TFTP Software and Servers Cisco TFTP Server.lnk • 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)
Summary (1/2)The router has several modes:• User EXEC mode• Privileged EXEC mode• Global configuration mode• Other configuration modesThe 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.