Cisco Router IOS

• Carries network protocols and functions
• Connects high-speed traffic between devices
• Adds security to control access
• Provides scalability for growth
• Supplies reliability

Connecting To A Cisco Router


Cisco 2811


Cisco 1841


Bringing up a Router

Boot-up process:

1: POST
2: Looks for the Cisco IOS from Flash memory
3: IOS loads & looks for a valid configuration;
startup-config
stored in nonvolatile RAM (NVRAM)
4: If a valid config is not found in NVRAM: setup mode


Logging into the Router

User mode:
Router>
Used mostly to view statistics

Privileged mode:
Router#
Used to view & change router configuration


Overview of Router Modes

Global changes:

config terminal or config t
Changes made to running-config (DRAM)
To change the startup-config (NVRAM)

config memory or config mem

Note: Any configuration changes need to be placed into RAM. Typing config mem or config net (from a TFTP host) will append the current running-config


Editing & Help Features


Enhanced Editing Commands



Router Command History


Gathering Basic Routing Information


Administrative Functions

The administrative functions that you can configure on a router and switch are

• Hostnames
• Banners
• Password
• Interface descriptions

Hostnames & Descriptions

Hostnames
Router(config)#hostname todd
todd(config)#

Descriptions
Atlanta(config)#int e0
Atlanta(config-if)#description Sales Lan


Banners

Purpose

Types

• exec
• incoming
• login
• motd

Delimiting character


Setting the Passwords

5 passwords:

1st two used to set your enable password
Used to secure privileged mode; Router>enable

Other three are used to configure a password in user mode via:

• console port
• auxiliary port
• Telnet

Passwords
Enable passwords
Router(config)#enable password cisco
Router(config)#enable secret cisco

Auxiliary Password
Console Password
Telnet Password

Encrypting Your Password
Router(config)#service password-encryption


Interface Descriptions

Setting descriptions on an interface is helpful to the administrator and, like the hostname, only locally significant. The description command is a helpful one because you can, for instance, use it to keep track of circuit numbers.

Here’s an example:
Atlanta(config)#int e0
Atlanta(config-if)#description Sales Lan
Atlanta(config-if)#int s0
Atlanta(config-if)#desc Wan to Miami circuit:6fdda4321

You can view the description of an interface either with the show running-config command or the show interface command.


Router Interfaces

Bringing up an Interface
no shutdown
shutdown
show interface

Configuring an IP Address on an Interface
Router(config)#int e0
Router(config-if)#ip address 172.16.10.2 255.255.255.0
Router(config-if)#no shut

Serial Interface Commands
clock rate & bandwidth (entered in kilobits)


Viewing, & Saving Configurations

Viewing & Saving Configurations
running-config saved in DRAM
startup-config saved in NVRAM
copy run start
sh run
sh start
erase startup-config


Verifying Your Configuration

• show running-config
• show startup-config
• ping
• show cdp nei detail
• trace
• telnet

Verifying with the show interface command
Router#show interface ?

Verifying with the show ip interface command
Router#show ip interface
Router#show ip interface brief
Router#show controllers