cisco ios

INTRODUCTION TO IOS AND CISCO ROUTERS By Anil Kumar Vishwakarma MCA,MCTS,CCNA CISCO ROUTER IOS o The Cisco IOS (Intern...

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INTRODUCTION TO IOS AND CISCO ROUTERS By Anil Kumar Vishwakarma MCA,MCTS,CCNA

CISCO ROUTER IOS o The Cisco IOS (Internetwork Operating System) was created to deliver network services and enable networked applications. It runs on most Cisco routers.

o Some of the important things that the Cisco router IOS software is responsible for include o o o o

Carrying network protocols and functions. Connecting high-speed traffic between devices. Adding security to control access and stop unauthorized network use. Supplying network reliability for connecting to network resources.

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

INTERNAL COMPONENT

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.

COMPUTER CONSOLE CONNECTION

MODEM CONNECTION

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.

MEMORY ARCHITECTURE

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

MEMORY TYPES

RAM (Working Memory)

Flash (IOS)

NVRAM (Startup Config)

ROM (Basic IOS)

CONFIGURATION AND IOS IMAGES

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)

SAVING A CONFIGURATION

Copy startup-config running-config RAM (Running-Config) Merged

Replaces NVRAM (Startup-Config)

Copy running-config startup-config

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

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

SETUP MODE  Setup     

Interface summary Router hostname Passwords SNMP Various network protocols 

 

Mode allows configuration of:

DECnet, Appletalk, IP, IPX

Routing protocols Interfaces

 When

finished setup mode gives the user the option of copying the configuration to NVRAM and RAM

VIEWING CONFIGURATIONS

Show {running-config|startup-config}

THE CLI AND GETTING HELP

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

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.

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 

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 

CONNECTING TO THE ROUTER

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

IOS MODES

IOS MODES Telnet

Aux

Console

User Mode

Router> enable

disable

Privileged (Enable) Mode

Router#

IOS CONFIGURATION MODES Privileged Mode

Router# Config terminal (config t)

Router (Router rip)

Configuration Mode

Router Configuration Mode

Router(config)#

Router(config-router)#

Interface (interface ethernet 0) Interface Configuration Mode

Router(config-if)#

ROUTER INTERFACES

INTERFACES  LANs   

Ethernet (Ethernet 0, E0, E1, etc.) FastEthernet (FastEthernet 0, F0, F1, etc.) Token Ring (TokenRing 0, TO0, TO1, etc.)

 WANs 

Serial 0, S0, S1, etc.

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

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

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 

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

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

SETTING THE CLOCK RATE  On

serial connections the DCE must set a clock rate to synchronize communication Router(config)#int s0 Router(config-if)#clockrate 2000000





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

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

PASSWORDS

PRIVILEGED MODE PASSWORDS 

Enable password Enable password  Enable password is shown in clear text  Not used if enable secret password is set 



Enable secret password Enable secret  Enable secret password is encrypted 

USER MODE PASSWORDS 

Console Line console 0 Login Password



Auxiliary Line aux 0 Login Password



Enter configuration mode Require login

Set password

Telnet Line vty 0 4 Login Password

Most routers have 5 telnet lines. This command sets all five.

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 no service password-encryption

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

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

IOS COMMANDS TO KNOW Show interface  Show controllers  Clock rate  Ip address  Show Version  Show flash 

Thank You