Lecture Notes For CCNA

Chapter 3 - IOS

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Login

Aux port with modem, console, or telnet

User / priveleged mode

exec= cisco ios command interpreter

Privelged needed to view config

Console

Enter to start

User password or straight to router> prompt

enable to get to priveleged mode .. enter password

disable to exit ...

n? shows all comands that start n etc.

clock set h:mmss dd mm yyyy

Advanced editing

terminal no editing to turn off, terminal editing to turn on

Control A = start of line

Control E = end of line

Control F or -> = right (forward

Control B or <- = left (back)

Control P or ^ = repeat last= previous command

Control N or v = repeat most recent command

Esc B = back 1 word

Esc F = Fwd 1 wors

show history - lists buffer

terminal history size - sets buffer size

tab key completes entry, eg sh run [tab] gives show running-config

Memory types

ROM, RAM, Flash, NVRAM

startup-config

in nvram.  accessed on boot and copied to dram

show startup-config

sh start

running-config

copied from nvram on startup

config [t]erminal updates the file.

copy running-config startup-config

copy run start

show running-config

sh run

cisco ios

Held in flash

sh flash to see size & free flash mem

CDP - Cisco Discovery Protocol

Cisco proprietary protocol

If SNAP runs at data link layer then devices can communicate even if different net layers as long as directly connected  - SNAP does not route.

Starts as default in IOS 10.3+

Data link broadcast allows it to find neighbouring routers running CDP

Can display other router's stats about protocols, eg IP / IPX

show cdp to see update and holdtime frequency.

cdp timer sets frequency (secs)

cdp holdtime

sh cdp [entry],[interface],[neighbors],[traffic]

sh cdp entry xxxxx where xxxxx is other router name

sh cdp int - encapsulation, timers etc.

sh cdp entry * shows all known cdp routers

sh cdp neighbor detail gives entry info. aswell as summary

sh cdp neighbor gives device id, local int, holdtime, capability, platform, port id.

EXEC mode

All run from router# prompt (not config t)

show startup-config

show running-config

copy run start

copy start run

erase startup-config - erase nvram settings to defaults!

reload - restarts router

setup - starts initial config. dialog

Continue with config dialog Y/N

control-c aborts config.

Passwords

enable secret

one way password for IOS 10.3 up.

precedence over enable password

set with enable secret within config t

enable

when no secret password or for older software

manually encrypted - setup in setup mode

set with enable password within config t

Keep different to secret - will warn not to set same but will not work if the same!

VTY - virtual terminal password

Telnet access

setup in setup mode

line vty 0 4 - specifies 0 - 4 are telnet sessions

to change pword:

config t

line vty 0 4

login

password xxxxxx

^z

no login means no password over telnet

line vty n  to setup different password for line n

Auxilliary password

for Aux modem access.

Set manually

config t

line aux 0

login

password xxxxx

^z

Console password

used with direct access to console port

config t

line con 0

login

password xxxxx

^z

Banners

banner exec

shown to user after login on telnet

banner incoming

Reverse telnet sessions show this but not exec

baner login

shows message before login command

banner motd #   where # send character (choose any)

first message shown on connection to router

banner motd #

This is the banner text for router xyz

#

end

Router ID

hostname [routername]

interfaces

2500 : serial0, serial1, ethernet0,tokenring0,fddi0

in config mode can use s0,s1,e0,t0,f0

Catalyst 5000 / other modular

numbered as type slot/port, eg e4/2

7000 / 7500

Has Versatile Int Proc cards

1/2 slots per port

type slot/port number adaptor/port, eg w2/0/1

shutdown - changes amin state of int, down

no shutdown - turns admin back on

description - adds text description to an interface (eg circuit nums)

hosts table

Setting up hosts entries

config t

ip host [name] [ip] [port for telnet]

ip host feathers 10.0.0.5 23

sh hosts

shows default domain, list of hosts, dns servers

Router startup ios commands

sh interface

general, inc ip, subnet mask

eth is up, line protocol is down

hardware, logical addresses

encapsulations, stats, errors etc.

sh ip interface

ip paramaters on an int.

Usability status - if hardware is working then int is up

if both ends of comms link are up then line protocol is up

sh protocol

displays all protocols and addresses running

sh ip protocol

shows routing protocols, eg rip, igrp etc

filters, period of update, routing type, which routes known

Cisco autoinstall procedure

Gets Ip thrugh BootP or RARP

Another router available with helper address fowards UDP TFTP broadcast to a TFTP server.

Helper also used to forward DHCP requests

New sends out BootP request & gets first address it is given

Uses TFTP server or DNS to resolve ip to hostname

TFTP send file named network-confg containing new hostname

network-confg file contains commands for all routers???

Requests config file from TFTP server called hostname-confg

If file doesn't exist TFTP server send generic file router-config

This file is used as running-config by router

SETUP routine

Get to this with either:

setup command within priv mode

write erase, erase startup-config then reboot

nvram invalid. posibly due to write errors - if new router, erased, or corrupt

Use Ctrl C to abort, enter initial config [yes] = enter

Would you like to see current interface summary [yes]=enter

list of interfacs. OK? column =no if no valid config

this proves the post found all the interfaces

Router name

enable secret password

enable password

vty password

snmp network management [yes]

configure ip [yes]

configure igrp routing [yes]

configure rip routing [no]

configurin interface paramaters:

int eth0:, is this int in use? [yes]

config ip on this int [yes]

ip addr: x.x.x.x

no. of bits in subnet field [0]

depends upon class.  eg class b, 8 bits = 255.255.255.0

int ser0:, is this in use? [yes]

config ip on this int.

ip addr x.x.x.x

bits in subnet field [0]

int ser1: is this in use [yes] : n

Use this configuration? [yes/no] :y - saves to nvram

Copy config files

config net - loads from tftp server to running ram only.

host or net config file [host]

ip addr of host

name of config file [router-confg]

confirm config [enter]

copy run tftp

backs up running config to tftp

enter ip addr

name of config file to write [host-confg]

confirm [enter]

copy tftp run

as above

copy tftp star

copy star tftp

Boot settings

Flash stores ios

copy flash tftp

lists files in flash

enter ip of tftp server

enter source filename

enter dest filename [enter] = same name

copy to server [y/n]

copy tftp flash

warning - routing stops, telnet stops

proceed enter to confirm

lists flash memory files

enter IP of TFTP server

source filename

dest filename [enter] for same#

erase flash before writing [enter] to confirm

contains file.  are you sure [enter] to confirm

copy xxx fom tfp into flash sure [y/n]

[e] erasing. [!] downloading.  May take 20 mins or more.

Reboots system

Use this to upgrade ios

boot command to choose multiple boot images:

enter in config mode, notconfig-in

boot system TFTP ios_filename tftp_ip_address

boot system flash

boot system TFTP filename 10.0.0.5

boot system rom

Will drop down to next in list if first not available - eg if flash corrupt then try tftp, if that fails try rom image.

IOS 11.3 oes not allow boot system rom, boot system flash bootflash

Manual config

config [network] or [terminal] or [memory]

config on own prompts for one of above

config mem

copies startup config to running config

config net

copies tftp image to running config

config t

(config)

int e0

(config-if)

description LAN link xyz etc.

ip address x.x.x.x subnet.s.s.s

no shutdown

int s0

description WAN link xyz

no shutdown

exit

(config)

hostname RouterABC

enable password xxxxx

enable secret yyyyy

line con 0

(config-line)

login

password vvvvvv

exit

(config)

line vty 0 4

(config-line)

login

password zzzzz

(config)

banner motd #

login message

more message

#

^z

DTE / DCE cable

if two routers connected directly by ser. then need clock

config t

int s0

clock rate 56000 [300-8000000]

bandwidth 56

int s1

clock rate 56000

bandwidth 56 [kbitsps]