Introduction to the Cisco IOS

1

• Introduction to the Cisco IOS

2
Topics

• Using the Cisco Internetwork Operating System
  (IOS)
• Configuring IP addresses, subnet masks, and
  gateway addresses
• Administrative router functions

3
Cisco IOS

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

4
Cisco Router Ports
5
Router Startup

• Boot process
• 1 POST checks hardware and, if present, loads
  the Cisco IOS stored in Flash memory
• 2 After IOS is loaded, startup-config is looked
  for in NVRAM
• if startup-config is located it is copied to
  running-config in RAM
• If not, the router goes into setup mode

6
Router Setup Mode

• Initial Configuration Dialog
• Step-by-step configuration using the command-line
  interface
• can be bypassed
• A pre-written configuration file can be
  transferred instead using HyperTerminal

7
Logging into the Router

• User mode Login first
• at Routergt prompt
• Used mostly to view statistics
• Privileged mode Login second
• at Router prompt
• Administrator mode
• used to view change router configuration

8
Router Modes

• User
• Privileged
• Configuration
• Global configuration mode
• Type config t to start
• Changes are made to running-config in DRAM
• These changes become permanent if copied to
  startup-config in NVRAM
• Interface configuration mode
• type interface abbreviation to start
• Enter from Global configuration mode

9
Configuration

• CLI Prompts - gt, , (config)
• Interfaces S0, S1, E0, F0
• Sub-interfaces F0/0, F0/1
• Line Commands
• Routing Protocol Configurations

10
Help Features

• To view list of features for a given mode
• Enter ?
• Part of a command and ?
• A command history is also saved as you enter
  commands

11
Keyboard Editing Commands
12
More Keyboard Editing Commands
13
Router Command History
14
Gathering Basic Routing Information

• Use the show version command to view information
  relevant to router capacities

15
Configurable Administrative Functions

• Hostnames
• Banners
• Password
• Interface descriptions

16
Hostnames Descriptions

• Hostnames
• Router(config)hostname todd
• todd(config)
• Descriptions
• Atlanta(config)int e0
• Atlanta(config-if)description Sales Lan

17
Banners

• Purpose display info or warnings
• Types
• exec
• incoming
• login
• motd
• Delimiting character

18
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

19
Interface Descriptions

• Optional
• Locally significant
• Administrator defined
• Example
• Atlanta(config)int e0
• Atlanta(config-if)description Sales Lan
• Atlanta(config-if)int s0
• Atlanta(config-if)desc Wan to Miami
  circuit6fdda4321
• View with show running-config or show interface
  commands

20
Router Interfaces

• Use no shutdown command to enable an Interface
• Configuring an IP Address
• Router(config)int e0
• Router(config-if)ip address 172.16.10.2
  255.255.255.0
• Router(config-if)no shut
• Serial Interfaces require bandwidth settings
• clock rate and bandwidth commands (entered in
  kilobits)

21
Viewing, Saving Configurations

• Viewing Saving Configurations
• running-config
• saved in DRAM
• startup-config
• saved inNVRAM
• relevant Commands
• copy run start
• sh run
• sh start
• erase startup-config

22
Verifying Your Configuration

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

23
Other Verification Methods

• Verifying with the show interface command
• Routershow interface ?
• Verifying with the show ip interface command
• Routershow ip interface
• Routershow ip interface brief
• Routershow controllers