2. CISCO ROUTER IOS
oThe Cisco IOS (Internetwork Operating System) was
created to deliver network services and enable networked
applications. It runs on most Cisco routers.
oSome of the important things that the Cisco router IOS
software is responsible for include
o Carrying network protocols and functions.
o Connecting high-speed traffic between devices.
o Adding security to control access and stop unauthorized
network use.
o Supplying network reliability for connecting to network
resources.
3. CISCO ROUTER
Router uses to connect: -
Subnet with another Subnet (By LAN
Interface).
LAN with another LAN (By WAN Interface).
LAN with WAN (By WAN Interface).
WAN with another WAN (By WAN Interface).
Router Consist of External Components
(Interfaces) and Internal Components
6. CONNECTING TO A CISCO ROUTER
You can connect to a Cisco router to configure
it, verify its configuration, and check statistics.
There are Three ways to do that: -
Console Session.
Auxiliary Session.
Telnet Session can’t use this method after router has
taken valid IP address.
9. BRINGING UP A ROUTER
When you first bring up a router, it will
takes this Boot Sequence: -
Perform POST (Power On Self Test) which is
small program stored in ROM to check
router components.
Load IOS image from Flash memory and
decompress it into RAM.
Display the information from POST.
Running Valid Configuration (Startup Conf).
If no configuration router will go into Setup
mode.
11. MEMORY TYPES
RAM
Used to store working tables as well as
running IOS image
ROM
Stores a bootable IOS image that provides
basic functionality as well as a barebones
interface called the ROM Monitor (ROMMON)
Flash Memory
Stores the full function IOS image and is the
default location for IOS at boot
NVRAM
Stores startup configuration file
14. CONFIGURATION FILE
The configuration is a text file that
contains configuration commands that are
executed at startup
When the router boots a copy of the config
in NVRAM (startup-config) is executed to
establish the initial configuration
Configuration commands entered while
the router is running are entered into the
temporary configuration stored in RAM
(running-config)
16. SYNTAX OF THE COPY COMMAND
Copy From-Location To-Location
Where:
From- and To-Location - {tftp|running-config|startup-config}
tftp – a trivial ftp server located somewhere on the network
17. ENTERING THE CONFIGURATION
Setup Mode
If no configuration exists when the router
boots, it enters setup mode
Router hasn‟t been configured before
Someone used the „Erase Startup-Config‟ then
rebooted
NVRAM was damaged
Setup mode is a question and answer process
that can be used to create basic configurations
Command Line Interface (CLI)
Configuration commands entered at command
prompt then saved to NVRAM
18. SETUP MODE
Setup Mode allows configuration of:
Interface summary
Router hostname
Passwords
SNMP
Various network protocols
DECnet, Appletalk, IP, IPX
Routing protocols
Interfaces
When finished setup mode gives the user
the option of copying the configuration to
NVRAM and RAM
21. COMMAND LINE INTERFACE
Most Cisco devices use a command line
interface
Commands can be entered and edited
before they are executed by hitting the
enter key
Commands can be abbreviated as long as
they are not ambiguous
e.g. Show Interface => sh int
22. COMMAND LINE INTERFACE
If a command has an error the command will be repeated
and a “^” will mark the location of the error
access-list 110 permit host 1.1.1.1
^
%Invalid input detected at „^‟ marker.
23. COMMAND HISTORY
Up and Down arrows scroll through command history
Also ctrl+p (up) and ctrl+n (down)
Command history commands
Show history – shows commands in history
Show terminal – shows terminal configurations and terminal history
size (default = 10)
Terminal history size – changes history buffer size up to a max of 256
24. GETTING HELP
Typing ? at any point will cause IOS to show
what options exist at that point
Just ? on a line will list all commands available in
that mode
Typing one letter followed by ? will show all
commands that begin with the letter
Adding ? after a command will show what arguments
are available for the command
26. CONNECTING TO THE ROUTER
Console
Connect directly to console port and use a terminal
program like Windows Hyperterminal or Linux‟s
Minicom
AUX
The auxiliary port is port you can attach a modem to
Can also be used as a backup connection dial on
demand circuit
TTY
Can use Telnet to connect to TTY once router has
been configured initially
Most routers have 5 TTY connections
32. INTERFACES ON EXPANSION CARDS
Interfaces on add in expansion cards include the
slot number followed by a slash then the
interface number
The first FastEthernet interface on a card in the first
slot would be FastEthernet 0/0
On 7500 series routers three values are required
(slot/port-adapter/port) so it would be
FastEthernet 0/0/0 for example
33. LOOPBACK INTERFACES
Loopback interfaces are internal interfaces and
treated like other interfaces
Loopback interfaces are never shutdown
Loopback interfaces are useful when you need an
interface that will never go down
34. INTERFACE CONFIGURATION MODE
Use the Interface command in configuration or
interface configuration mode to enter
configuration mode
Router(config)#interface e0
Router(config-if)#interface Lo0
Router(config)#interface s0/1
35. BRINGING UP AN INTERFACE
By default, all interfaces (except loopback
interfaces) are in administrative shutdown mode
To activate the interface use the no shutdown
command in the interface configuration mode
36. ASSIGNING AN IP ADDRESS
IP addresses are assigned in interface
configuration mode
Router#config t
Router(config)#interface s0
Router(config-if)#ip address 129.130.32.1 255.255.224.0
Router(config-if)#no shutdown
Router(config-if)#exit
37. SETTING THE CLOCK RATE
On serial connections the DCE must set a
clock rate to synchronize communication
In the lab the 2501 that is a router is a DCE
because the cable attached is a DCE cable so the
clock rate must be set on this router
The 2501 that is a Frame Relay switch is also a
DCE but you do not configure this one
Router(config)#int s0
Router(config-if)#clockrate 2000000
38. SETTING THE SERIAL
ENCAPSULATION
We‟ll discuss this in more detail later in the
semester but the data link layer protocol must be
set for the Frame Relay link using the
encapsulation command
Router(config)#interface s0
Router(config-if)#encapsulation frame-relay
40. PRIVILEGED MODE PASSWORDS
Enable password
Enable password <password>
Enable password is shown in clear text
Not used if enable secret password is set
Enable secret password
Enable secret <password>
Enable secret password is encrypted
41. USER MODE PASSWORDS
Console
Line console 0
Login
Password <password>
Auxiliary
Line aux 0
Login
Password <password>
Telnet
Line vty 0 4
Login
Password <password>
Enter configuration mode
Require login
Set password
Most routers have 5 telnet
lines. This command sets
all five.
42. ENCRYPTING PASSWORDS
User mode passwords are normally stored
in the configuration file in clear text
To encrypt them use the following
sequence of commands
service password-encryption
line console 0
login
password <password>
no service password-encryption
43. IOS COMMANDS TO KNOW
Enable/disable
Enable secret/password
Config
Editing commands
Show history
Show terminal
Terminal history size
Line
How to require login and set password for
console, vty and aux
44. IOS COMMANDS TO KNOW
Service password-encryption
Banner
Interface
Shutdown
Know the interfaces commands for ethernet,
fast ethernet, serial, token ring and loopback
Description
Hostname
Show running/startup-config
Copy <running-config/startup-config,tftp>
<running-config/startup-config,tftp>
45. IOS COMMANDS TO KNOW
Show interface
Show controllers
Clock rate
Ip address
Show Version
Show flash