Entering Global Configuration Mode Configuring a Router Name This command works on both routers and switches.. Routerconfig-subif# Subinterface mode Routerconfig-line# Line mode Routerconf
Trang 1PART III
Configuring a Router
Chapter 6 Configuring a Single Cisco Router
Trang 2This page intentionally left blank
Trang 3• Entering global configuration mode
• Configuring a router, specifically
— Names
— Passwords
— Password encryption
— Interface names
— Moving between interfaces
— Configuring a serial interface
— Configuring a Fast Ethernet interface
— Creating a message-of-the-day (MOTD) banner
— Creating a login banner
— Setting the clock time zone
— Assigning a local host name to an IP address
— The no ip domain-lookup command
— The logging synchronous command
— The exec-timeout command
— Saving configurations
— Erasing configurations
• show commands to verify the router configurations
• EXEC commands in configuration mode: the do command
Router Modes
Router# Privileged mode (also known as EXEC-level mode)Router(config)# Global configuration mode
Router(config-if)# Interface mode
Trang 454 Configuring Passwords
careful If you type in a command that you know is correct—show running-config,
for example—and you get an error, make sure that you are in the correct mode
Entering Global Configuration Mode
Configuring a Router Name
This command works on both routers and switches
Configuring Passwords
These commands work on both routers and switches
Router(config-subif)# Subinterface mode
Router(config-line)# Line mode
Router(config-router)# Router configuration mode
You cannot make changes in this mode
move to make changes
Router#c c co o on nf n fi f i ig g gu u ur re r e e t t te er e rm r m mi i in n na al a l
Router(config)#
Moves to global configuration mode This prompt indicates that you can start making changes
Router(config)#h h ho o os s st tn t na n a am m me e e C C Ci i is s sc co c o The name can be any word you
choose
Cisco(config)#
Router(config)#e e en n na a ab bl b le l e e p p pa as a s ss s sw w wo or o r rd d d c ci c is i s sc c co o Sets enable password
Router(config)#e e en n na a ab bl b le l e e s s se ec e c cr r re e et t t c c cl l la as a ss s s Sets enable secret password
Trang 5Password Encryption 55
CAUTION: The enable secret password is encrypted by default The enable
password is not For this reason, recommended practice is that you never use the
enable password command Use only the enable secret password command in a
router or switch configuration
You cannot set both enable secret password and enable password to the same
password Doing so defeats the use of encryption
Password Encryption
Router(config)#l l li i in n ne e e c c co o on n ns so s o ol l le e e 0 0 Enters console line mode
Router(config-line)#p p pa a as ss s sw s w wo o or r rd d d c c co o on ns n so s o ol l le e Sets console line mode password to
console
Router(config-line)#l l lo o og gi g in i n Enables password checking at loginRouter(config)#l l li i in n ne e e v v vt t ty y y 0 0 0 4 4 Enters vty line mode for all five vty
linesRouter(config-line)#p p pa a as ss s sw s w wo o or r rd d d t t te e el ln l ne n e et t Sets vty password to telnet
Router(config-line)#l l lo o og gi g in i n Enables password checking at loginRouter(config)#l l li i in n ne e e a a au u ux x x 0 0 Enters auxiliary line mode
Router(config-line)#p p pa a as ss s sw s w wo o or r rd d d b b ba a ac ck c kd k d do o oo o or r Sets auxiliary line mode password to
Router(config)#e e en n na a ab bl b le l e e p p pa as a s ss s sw w wo or o r rd d d c ci c is i s sc c co o Sets enable password to cisco
Router(config)#l l li i in n ne e e c c co o on n ns so s o ol l le e e 0 0 Moves to console line mode
Router(config-line)#p p pa a as ss s sw s w wo o or r rd d d C C Ci i is sc s co c o Continue setting passwords as above
.Router(config)#n n no o o s se s er e r rv v vi i ic ce c e e p p pa as a s ss s sw w wo or o rd r d d- - Turns off password encryption
Trang 656 Interface Names
CAUTION: If you have turned on service password encryption, used it, and then turned it off, any passwords that you have encrypted will stay encrypted New passwords will remain unencrypted
Interface Names
One of the biggest problems that new administrators face is the interface names on the different models of routers With all the different Cisco devices in production networks today, some administrators are becoming confused about the names of their interfaces
The following chart is a sample of some of the different interface names for various routers
This is by no means a complete list Refer to the hardware guide of the specific router that you are working on to see the different combinations, or use the following command
to see which interfaces are installed on your particular router:
2501 On board Ethernet Interface-type number ethernet0 (e0)
On board Serial Interface-type number serial0 (s0) &
s1
2514 On board Ethernet Interface-type number e0 & e1
On board Serial Interface-type number s0 & s1
1721 On board Fast Ethernet Interface-type number fastethernet0
(fa0)
interface card) (serial)
Interface-type number s0 & s1
1760 On Board Fast Ethernet Interface-type 0/port fa0/0
Slot 0 WIC/VIC (voice
interface card)
Interface-type 0/port s0/0 & s0/1
v0/0 & v0/1Slot 1 WIC/VIC Interface-type 1/port s1/0 & s1/1
v1/0 & v1/1
Trang 7Interface Names 57
Slot 2 VIC Interface-type 2/port v2/0 & v2/1Slot 3 VIC Interface-type 3/port v3/0 & v3/1
2610 On board Ethernet Interface-type 0/port e0/0
Slot 0 WIC (Serial) Interface-type 0/port s0/0 & s0/1
2611 On board Ethernet Interface-type 0/port e0/0 & e0/1
Slot 0 WIC (Serial) Interface-type 0/port s0/0 & s0/1
2620 On board Fast Ethernet Interface-type 0/port fa0/0
Slot 0 WIC (serial) Interface-type 0/port s0/0 & s0/1
2621 On board Fast Ethernet Interface-type 0/port fa0/0 &
fa0/1Slot 0 WIC (serial) Interface-type 0/port s0/0 & s0/1
1841 On board Fast Ethernet Interface-type 0/port fa0/0 &
fa0/1Slot 0 High-speed
WAN interface card (HWIC)/
WIC/VWIC
Interface-type 0/slot/
port
s0/0/0 & s0/0/1
2801 On board Fast Ethernet Interface-type 0/port fa0/0 &
Trang 858 Moving Between Interfaces
Moving Between Interfaces
What happens in Column 1 is the same thing occurring in Column 3
Interface-type 0/port fa0/0 &
fa0/1 gi0/0 & gi0/1
& 0/1/1NME slot NM/NME Interface-type 1/port gi1/0 &
gi1/1 s1/0 & s1/1
se e er r ri ia i al a l l 0 0 0/ /0 / 0 0/ / /0 0
Moves to serial interface configurationmodeRouter(config-
if)#e e ex xi x it i t
Returns to global configuration mode
if)#i in i n nt t te e er rf r f fa a ac c ce e e f
Router(config-fa a as s st te t et e t th h he e er rn r n ne e et t t 0
0/ / /0 0
Moves directly
to Fast Ethernet 0/0 configuration mode
Trang 9Configuring a Fast Ethernet Interface 59
Configuring a Serial Interface
cable plugged into it There must be a clock rate set on every serial link between routers It does not matter which router has the DCE cable plugged into it or which interface the cable is plugged into Serial 0 on one router can be plugged into Serial 1 on another router
Configuring a Fast Ethernet Interface
if)#
Router(config-In Fast Ethernet 0/0 configuration mode nowRouter(config-
if)#
In Fast Ethernet 0/0 configuration mode now
if)#
Router(config-Prompt does not change; be
careful
Router(config)#i i in n nt t te er e rf r f fa a ac c ce e e s s s0 0 0/ /0 / 0 0/ / /0 0 Moves to serial interface 0/0/0
configuration modeRouter(config-if)#d de d es e s sc c cr r ri ip i p pt t ti i io on o n n L L Li in i nk n k k t t to o o I I IS S SP P Optional descriptor of the link is
locally significant Router(config-if)#i ip i p p a ad a dd d d dr r re e es ss s s s 1 19 1 92 9 2 2 .1 1 16 68 6 8 8 1 1 10 0 0 .1 1 1
Router(config)#i i in n nt t te er e rf r f fa a ac c ce e e f f fa a as st s t te e et t th he h er e r rn n ne e et t t 0 0 0/ / /0 0 Moves to Fast Ethernet 0/0
interface configuration modeRouter(config-if)#d de d es e s sc c cr r ri ip i p pt t ti i io on o n n A A Ac cc c co c o ou u un n nt ti t i in n ng g g
L
LA AN A N
Optional descriptor of the link is locally significantRouter(config-if)#i ip i p p a a ad d dd dr d r re e es s ss s s 1 1 19 9 92 2 2 1 1 16 6 68 8 8 .2 2 20 0 0 .1 1 1
Trang 1060 Setting the Clock Time Zone
Creating a Message-of-the-Day Banner
messages that affect all users Use the no banner motd command to disable the
MOTD banner The MOTD banner displays before the login prompt and the login banner, if one has been created
Creating a Login Banner
prompts Use the no banner login command to disable the login banner The
MOTD banner displays before the login banner
Setting the Clock Time Zone
character must surround the banner message and can be any character so long as it is not a character used within the body of the message
character must surround the banner message and can be any character so long as it is not a character used within the body of the message
Router(config)#c c cl l lo o oc ck c k k t t ti i im me m e ez z zo o on ne n e e E E ES ST S T T – – –5 5 Sets the time zone for
display purposes Based on coordinated universal time (Eastern standard time is
5 hours behind UTC.)
Trang 11The logging synchronous Command 61
Assigning a Local Host Name to an IP Address
to Telnet to a device, just enter the IP host name itself:
Router#l l lo o on nd n do d o on n n = = = R R Ro o ou ut u te t e er r r# # #t te t e el l ln n ne et e t t l l lo o on nd n d do o on n n = = = R R Ro ou o ut u t te e er r r# #t # t te e el l ln ne n et e t t 1 1 17 72 7 2 2 .1 1 16 6 6 1 1 1 .3 3
The no ip domain-lookup Command
or two as the router tries to translate your command to a domain server of
255.255.255.255? The router is set by default to try to resolve any word that is not
a command to a Domain Name System (DNS) server at address 255.255.255.255
If you are not going to set up DNS, turn off this feature to save you time as you type, especially if you are a poor typist
The logging synchronous Command
Router(config)#i i ip p p h ho h os o s st t t l lo l o on n nd d do on o n n 1 1 17 72 7 2 2 1 1 16 6 6 .1 1 1 .3 3 Assigns a host name to the
IP address After this assignment, you can use the host name rather than an IP address when trying to Telnet or ping to that address
Router(config)#n n no o o i ip i p p d d do o om ma m a ai i in n n- -l - l lo o oo o ok ku k up u p
Router(config)#
Turns off trying to automatically resolve an unrecognized command to a local host name
Router(config)#l l li i in n ne e e c c co o on n ns so s o ol l le e e 0 0 Moves to line console
configuration mode
Router(config-line)#l l lo o og gg g gi g i in n ng g g s s sy y yn n nc ch c hr h r ro o on n no ou o u us s Turns on synchronous
logging Information items sent to the console will not interrupt the command you are typing The command will be moved to a new line
Trang 1262 Erasing Configurations
middle of what you were typing? Lose your place? Do not know where you are in
synchronous command tells the router that if any informational items get
displayed on the screen, your prompt and command line should be moved to a new line, so as not to confuse you
The informational line does not get inserted into the middle of the command you are trying to type If you were to continue typing, the command would execute properly, even though it looks wrong on the screen
The exec-timeout Command
console never logs out This is considered to be bad security and is dangerous in
the real world The default for the exec-timeout command is 10 minutes and zero (0) seconds (exec-timeout 10 0).
Saving Configurations
Erasing Configurations
clear the running configuration
Router(config)#l l li i in n ne e e c c co o on n ns so s o ol l le e e 0 0 Moves to line console
configuration mode
Router(config-line)#e e ex x xe ec e c- c - -t t ti i im me m e eo o ou u ut t t 0 0 0 0 0 Sets the time limit when the
console automatically logs
off Set to 0 0 (minutes
seconds) means the console never logs off
Trang 13show Commands 63
show Commands
Router#s s sh h ho ow o w w ? ? Lists all show commands available.
Router#s s sh h ho ow o w w i i in n nt te t e er r rf f fa ac a ce c e es s Displays statistics for all interfaces.Router#s s sh h ho ow o w w i i in n nt te t e er r rf f fa ac a ce c e e s s se er e r ri i ia a al l l 0 0 0/ / /0 0 0/ /0 / 0 Displays statistics for a specific
interface (in this case, serial 0/0/0).Router#s s sh h ho ow o w w i i ip p p i i in n nt t te er e rf r f fa a ac c ce e e b b br r ri ie i ef e f Displays a summary of all
interfaces, including status and IP address assigned
Router#s s sh h ho ow o w w c c co o on nt n t tr r ro o ol ll l le l e er r rs s s s s se e er r ri ia i al a l l 0 0 0/ /0 / 0 0/ / /0 0 Displays statistics for interface
hardware Statistics display if the clock rate is set and if the cable is DCE, DTE, or not attached
Router#s s sh h ho ow o w w c c cl l lo oc o c ck k Displays time set on device
Router#s s sh h ho ow o w w h h ho o os st s t ts s Displays local host-to-IP address
cache These are the names and addresses of hosts on the network to which you can connect
Router#s s sh h ho ow o w w u u us s se er e r rs s Displays all users connected to
device
Router#s s sh h ho ow o w w h h hi i is st s t to o or r ry y Displays the history of commands
used at this edit level
Router#s s sh h ho ow o w w f f fl l la as a s sh h Displays info about flash memory.Router#s s sh h ho ow o w w v v ve e er rs r s si i io o on n Displays info about loaded software
version
Router#s s sh h ho ow o w w a a ar r rp p Displays the Address Resolution
Protocol (ARP) table
Router#s s sh h ho ow o w w p p pr r ro ot o t to o oc c co ol o ls l s Displays status of configured Layer
Trang 1464 Configuration Example: Basic Router Configuration
EXEC Commands in Configuration Mode: The do Command
such as show, clear, or debug, while remaining in global configuration mode or in any configuration submode You cannot use the do command to execute the configure terminal command because it is the configure terminal command that
changes the mode to global configuration mode
Configuration Example: Basic Router Configuration
Figure 6-1 illustrates the network topology for the configuration that follows, which shows
a basic router configuration using the commands covered in this chapter
Figure 6-5 Network Topology for Basic Router Configuration
Boston Router
Router(config)#d d do o o s sh s ho h o ow w w r ru r u un n nn n ni in i n ng g g- - -c co c on o n nf f fi i ig g Executes the privileged-level show
running-config command while in
global configuration mode
configuration mode after the command has been executed
Router>e e en n na ab a bl b l le e Enters privileged mode.Router#c c cl l lo oc o ck c k k s s se et e t t 1 1 18 8: 8 :3 : 3 30 0 0: : :0 00 0 0 0 1 1 15 5 5 M M Ma a ay y y 2 2 20 0 00 0 07 7 Sets the local time on the
172.16.10.10
s0/0/1 DCE
172.16.20.2 fa0/0
172.16.10.1
s0/0/0 172.16.20.1
Boston-2811
Buffalo-2811
172.16.30.30 fa0/0
172.16.30.1
Trang 15Configuration Example: Basic Router Configuration 65
Creates an MOTD banner
Boston(config)#c c cl l lo o oc ck c k k t t ti i im me m e ez z zo o on ne n e e E E ES ST S T T – – –5 5 Sets time zone to eastern
standard time (–5 from UTC).Boston(config)#e e en n na a ab bl b le l e e s s se ec e c cr r re e et t t c c ci i is sc s co c o Enables secret password set to
Boston(config-line)#p p pa a as ss s sw s w wo o or r rd d d c c cl l la as a ss s s Sets the password to class.
Boston(config-line)#l l lo o og gi g in i n Enables password checking at
login
Boston(config-line)#l l li i in ne n e e v v vt t ty y y 0 0 0 4 4 Moves to virtual Telnet lines 0
through 4
Boston(config-line)#p p pa a as ss s sw s w wo o or r rd d d c c cl l la as a ss s s Sets the password to class.
Boston(config-line)#l l lo o og gi g in i n Enables password checking at
Trang 1666 Configuration Example: Basic Router Configuration
2
25 55 5 5 5 .2 2 25 55 5 5 5 2 2 25 5 55 5 5 0 0
Assigns an IP address and subnet mask to the interface.Boston(config-if)#n no n o o s s sh h hu ut u t td d do o ow wn w n Turns on the interface.Boston(config-if)#i in i nt n t te e er r rf fa f a ac c ce e e s s se e er r ri ia i al a l l 0 0 0/ /0 / 0 0/ / /0 0 Moves directly to interface
serial 0/0/0 configuration mode
2
25 55 5 5 5 .2 2 25 55 5 5 5 2 2 25 5 55 5 5 2 2 25 5 52 2
Assigns an IP address and subnet mask to the interface.Boston(config-if)#c cl c lo l o oc c ck k k r r ra a at t te e e 5 5 56 6 60 00 0 00 0 0 Sets a clock rate for serial
transmission The DCE cable must be plugged into this interface
Boston(config-if)#n no n o o s s sh h hu ut u t td d do o ow wn w n Turns on the interface.Boston(config-if)#e ex e xi x i it t Moves back to global
configuration mode
Boston(config)#i i ip p p h ho h os o s st t t b bu b u uf f ff f fa al a l lo o o 1 17 1 72 7 2 2 .1 1 16 6 6 2 2 20 0 0 .2 2 Sets a local host name
resolution to IP address 172.16.20.2
Boston(config)#e e ex x xi i it t Moves back to privileged
mode
Boston#c c co o op py p y y r r ru u un nn n n ni i in n ng g- g -c - c co o on n nf fi f i ig g g s st s ta t a ar r rt t tu up u p p- - -c c co on o n nf f fi i ig g Saves the running
configuration to NVRAM
Trang 18This page intentionally left blank
Trang 19CHAPTER 7
Static Routing
This chapter provides information and commands concerning the following topics:
• Configuring a static route on a router
• The permanent keyword (optional)
• Static routes and administrative distance (optional)
• Configuring a default route on a router
• Verifying static routes
• Configuration example: Static routes
Configuring a Static Route on a Router
When using the ip route command, you can identify where packets should be routed
in two ways:
• The next-hop address
• The exit interface
Both ways are shown in the “Configuration Example: Static Routes” and the
“Configuring a Default Route on a Router” sections
Router(config)#i i ip p p r r ro o ou u ut te t e e 1 1 17 7 72 2 2 1 1 16 6 6 .2 20 2 0 0 .0 0 0
2
25 5 55 5 5 .2 25 2 5 55 5 5 .2 25 2 55 5 5 5 .0 0 0 1 1 17 7 72 2 2 .1 16 1 6 6 .1 1 10 0 0 2 2
172.16.20.0 = destination network
255.255.255.0 = subnet mask.172.16.10.2 = next-hop address.Read this to say, “To get to the destination network of 172.16.20.0, with a subnet mask
of 255.255.255.0, send all packets
255.255.255.0 = subnet mask.Serial 0/0/0 = exit interface.Read this to say, “To get to the destination network of 172.16.20.0, with a subnet mask
of 255.255.255.0, send all packets out interface serial 0/0/0.”