Transcript cisco router configuration basics
cisco router configuration basics
cisco router configuration NTW2000 / track 2 # 1
overview
router configuration controls the operation of the router: interface address and netmask routing information (static or dynamic) booting and startup information security (passwords) cisco router configuration NTW2000 / track 2 # 2
overview
configuration statements have different contexts: global: enable-password
mysecret
interface: interface ethernet0 ip address 195.176.118.254 255.255.255.0
router:
router ospf 1 network 195.176.118.0 0.0.0.255 area 0 cisco router configuration NTW2000 / track 2 # 3
global configuration
global configuration statements are independent of any particular interface or routing protocol,
e.g.
: hostname
myrouter
enable-password
mysecret
service password-encryption logging facility
local0
logging
195.176.118.42
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global configuration
ip-specific global configuration statements: ip classless static route creation: ip route
195.176.118.0 255.255.248.0 195.176.31.1
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interface configuration
interfaces are named by type and position;
e.g.
: ethernet0, ethernet1,... ethernet5 serial0, serial1 ... serial3 and can be abbreviated: ethernet0 or eth0 or e0 serial0 or ser0 or s0 cisco router configuration NTW2000 / track 2 # 6
interface configuration
ip address and netmask configuration, using interface commands
(interactive configuration example, showing prompts):
router#config terminal router(config)#interface e0 router(config-if)#ip address
195.176.118.254 255.255.255.0
router(config-if)#no shutdown router(config-if)#^Z router# cisco router configuration NTW2000 / track 2 # 7
There are two modes on a cisco router
normal mode router> enable mode router> enable router# config terminal cisco router configuration NTW2000 / track 2 # 8
interface configuration
administratively enable/disable the interface router(config-if)#no shutdown router(config-if)#shutdown (config-if)# no ip proxy-arp (config-if)# no ip directed broadcast (config-if)# no ip redirect description #description 128k circuit 123-ABC to hotel cisco router configuration NTW2000 / track 2 # 9
where is the configuration?
router always has two configurations: running configuration in RAM, determines how the router is currently operating is changed by using the configuration command to see it: show running startup configuration in NVRAM, determines how the router will operate after next reload is changed using the copy command to see it: show startup cisco router configuration NTW2000 / track 2 # 10
where is the configuration?
can also be stored in more permanent places: external hosts, using TFTP to move it around in flash memory in the router copy command is used to move it around copy run start copy run tftp copy start tftp copy tftp start copy flash start copy start flash cisco router configuration NTW2000 / track 2 # 11
looking at the configuration
use “show running-configuration” to see the current configuration use “show startup-configuration” to see the configuration in NVRAM, that will be loaded the next time the router is rebooted or reloaded cisco router configuration NTW2000 / track 2 # 12
changing the configuration
configuration statements can be entered interactively at the console, or in a telnet session, or, edited in a text file and uploaded to the router at a later time; some configuration statements, especially access lists, are very difficult to work with interactively, so editing and uploading the file is the only practical way to work; also allows version control and auditing changes cisco router configuration NTW2000 / track 2 # 13
interactive configuration
can use direct serial connection to console port, or telnet to vty’s (“virtual terminals”), or modem connection to aux port in every case, changes are made (almost) immediately, to the running configuration cisco router configuration NTW2000 / track 2 # 14
interactive configuration
enter configuration mode, using “configure term” prompt gives a hint about where you are:
router#
configure terminal
router(config)#
hostname K-rtr
K-rtr(config)#
ip classless
K-rtr(config)#
ip subnet-zero
K-rtr(config)#
interface ethernet3
K-rtr(config-if)#
ip address 195.176.118.253 255.255.255.0
K-rtr(config-if)#
no shutdown
use the no command to nullify command given: (config-if)#
cisco router configuration no ip addr 195.176.118.253 255.255.255.0
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storing the configuration on a host
requires: `tftpd’ on a unix host; destination file must exist before the file is written and must be world writable...
copy run tftp K-rtr#copy run tftp Remote host []? 195.176.118.42
Name of configuration file to write [K-rtr-confg]? /usr/local/tftpd/K-rtr-confg Write file /usr/local/tftpd/K-rtr-confg on... host 195.176.118.42? [confirm] Building configuration...
Writing /usr/local/tftpd/K-rtr-confg !![OK] cisco router configuration NTW2000 / track 2 # 16
restoring the configuration from a host
use ‘tftp’ to pull file from unix host, copying to running config or startup K-rtr#copy tftp start Address of remote host [255.255.255.255]? 195.176.118.42
Name of configuration file [K-rtr-confg]?
Configure using K-rtr-confg from 195.176.118.42? [confirm] Loading K-rtr-confg from 195.176.118.42 (via Ethernet0): !
[OK - 1005/128975 bytes] [OK] K-rtr# reload cisco router configuration NTW2000 / track 2 # 17
getting help
IOS has a built-in help facility; use “?” to get a list of possible configuration statements “?” after the prompt lists all possible commands: router#?
“
router#show ip ?
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getting help
“
configure connect this is different (space before “?”): router#conf ?
memory Configure from NV memory network Configure from a TFTP network host overwrite-network Overwrite NV memory from TFTP...
getting help
this also works in configuration mode: router(config)#ip a?
accounting-list accounting-threshold accounting-transits address-pool alias as-path router(config)#int e0 router(config-if)#ip a?
access-group accounting address cisco router configuration NTW2000 / track 2 # 20
getting help
can “explore” a command to figure out the syntax: router(config-if)#ip addr ?
A.B.C.D IP address router(config-if)#ip addr 169.222.64.1 ?
A.B.C.D IP subnet mask router(config-if)#ip addr 169.222.64.1 255.255.255.0 ?
secondary Make this IP address a secondary address
router(config-if)# cisco router configuration NTW2000 / track 2 # 21
getting lazy help
TAB character will complete a partial word router(config)#int
router(config)#interface et
router(config)#interface ethernet 0 router(config-if)#ip add
router(config-if)#ip address ... 195.176.118.1 255.255.255.0
not really necessary; partial commands can be used: router#conf t router(config)#int e0 router(config-if)#ip addr 195.176...
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getting lazy
command history IOS maintains short list of previously typed commands up-arrow or ‘ ^P ’ recalls previous command down-arrow or ‘^N’ recalls next command line editing left-arrow, right-arrow moves cursor inside command ‘^D’ or backspace will delete character in front of cursor cisco router configuration NTW2000 / track 2 # 23