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cisco router configuration basics

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overview router configuration controls the operation of the router: interface address and netmask routing information (static or dynamic) booting and startup ... – PowerPoint PPT presentation

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Title: cisco router configuration basics

1
cisco router configuration basics
2
overview

router configuration controls the operation of
the router
interface address and netmask
routing information (static or dynamic)
booting and startup information
security (passwords)

3
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

4
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

5
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

6
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

7
interface configuration

ip address and netmask configuration, using
interface commands (interactive configuration
example, showing prompts)
routerconfig 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

8
There are two modes on a cisco router

normal mode
routergt
enable mode
routergt enable
router config terminal

9
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

10
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

11
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

12
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

13
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

14
interactive configuration

can use direct serial connection to console port,
or
telnet to vtys (virtual terminals), or
modem connection to aux port
in every case, changes are made (almost)
immediately, to the running configuration

15
interactive configuration

enter configuration mode, using configure term
prompt gives a hint about where you are
routerconfigure 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) no ip addr 195.176.118.253
255.255.255.0

16
storing the configuration on a host

requires tftpdon a unix host destination file
must exist before the file is written and must be
world writable...
copy run tftp
K-rtrcopy 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

17
restoring the configuration from a host

use tftp to pull file from unix host, copying
to running config or startup
K-rtrcopy 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

18
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?
ltpartial commandgt ? lists all possible
subcommands, e.g.
routershow ?
routershow ip ?

19
getting help

ltpartial commandgt? shows all possible command
completions
routercon?
configure connect
this is different (space before ?)
routerconf ?
memory Configure from NV memory
network Configure from a TFTP
network host
overwrite-network Overwrite NV memory from
TFTP... network host
terminal Configure from the terminal
ltcrgt

20
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

21
getting help