CCNA Guide to Cisco Networking Fundamentals Fourth Edition

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CCNA Guide to Cisco Networking Fundamentals
Fourth Edition

• Chapter 5
• Router and IOS Basics

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Objectives

• Describe the benefits of network segmentation
  with routers
• Understand the elements of the Cisco router user
  interface
• Configure the HyperTerminal program to interface
  with the Cisco router
• Describe the various router configuration modes

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Objectives (continued)

• Describe the various router passwords
• Understand the enhanced editing features of the
  Cisco IOS
• Compare router components to typical PC components

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Benefits of Routing

• Routers provide
• Packet filtering
• Connections between local networks
• Traffic control
• Wide area network (WAN) connections
• Routers operate at the Network layer of the OSI
  reference model
• Because of Network layer addressing, routers can
  direct packets to both local and remote segments

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Cisco Router User Interface

• Cisco Internetwork Operating System (IOS)
• Provides a command-line interface (CLI)
• Allows network operators to check the status of
  the router and network administrators to manage
  and configure the router
• You can access a router in several different ways
• Console port (also known as the console)
• Auxiliary port (AUX)
• Virtual terminals (VTY)
• Trivial File Transfer Protocol (TFTP) server

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Connecting via Terminal Programs

• When configuring the router through the console
  or AUX ports
• You must first make the physical connection
• Then, you can access the router through a
  terminal program
• Steps to configure HyperTerminal
• Open the HyperTerminal application
• Click File on the menu bar, and then click New
  Connection
• Enter a name for the connection

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Connecting via Terminal Programs (continued)

• Steps to configure HyperTerminal (continued)
• Configure how you will connect to the router via
  the Connect To dialog box
• If you are connecting to the router through the
  AUX port, you would provide the router phone
  number here
• If connecting to the router through the console
  port, click the Connect using list box and
  choose the COM port to which the RJ-45 to DB-9
  connector is attached
• Configure the following settings for the COM
  port Bits per second, 9600 Data bits, 8
  Parity, None Stop bits, 1 Flow control, None

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System Configuration Dialog

• If the router has not been configured previously,
  or if the startup file has been erased
• The Cisco IOS will prompt you to run the initial
  configuration dialog after the router boots
• The system configuration dialog presents a series
  of prompts that guide you through the initial
  configuration for the router

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User Interface

• The initial prompt consists of two parts
• The host name of the router followed by the
  greater than symbol (gt)
• Default routergt
• User EXEC mode (or user mode)
• When the prompt displayed is the greater than
  symbol
• Network operator can check router status and
  review several of the router settings

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User Interface (continued)

• The question mark activates context-sensitive
  Help on the Cisco router
• User mode does not allow you to configure the
  router
• To do this, you must go into the privileged EXEC
  mode
• To enter privileged EXEC, you can type the enable
  command at the user mode prompt
• Next, you may be prompted for a password
• Greater than symbol (gt) changes to a pound sign
  ()

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User Interface (continued)

• You can do a few things at this prompt
• Setup the setup command will cause the router to
  enter the system configuration dialog
• Copy configurations can be copied from TFTP
  servers to the router and therefore change the
  router configuration
• Erase configuration files as well as the entire
  IOS can be erased

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Configuration Modes

• Global configuration mode
• Accessed by typing configure terminal at the
  enable mode prompt
• Interface configuration mode
• Allows you to configure the Ethernet and serial
  interfaces on your router
• Line configuration mode
• Allows you to configure the virtual terminals,
  console, and AUX lines that let you access the
  router

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Configuration Modes (continued)

• Typing exit will take you back one level
• Typing end or pressing the CtrlZ keys will take
  you all the way back to the enable prompt
• Often, you can discover abbreviated commands by
  simply trying them
• The router will show you the point at which you
  entered an incorrect character

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Configuration Modes (continued)
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Plethora of Passwords
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Plethora of Passwords (continued)

• Enable Password and Enable Secret Password
  configuration
• You can set both passwords from the global
  configuration mode prompt
• Because it is encrypted, the enable secret
  password is more secure than the enable password
• You can type no enable secret and no enable
  password at the global configuration mode prompt
• To remove the enable secret and enable passwords

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Plethora of Passwords (continued)
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Plethora of Passwords (continued)

• Setting Line passwords
• Line passwords are the first line of defense
  against unauthorized intrusion into the router
• You can set passwords for each line used to
  configure the router
• Configure the console line password
• Enter line configuration mode
• You can also configure passwords on the five
  virtual terminal lines that exist on every router
• In much the same way as on the console port

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Plethora of Passwords (continued)
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Plethora of Passwords (continued)
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Plethora of Passwords (continued)
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Enhanced Editing

• By default, the router supports enhanced editing
  features that allow you to modify lengthy
  commands
• The enhanced editing commands let you jump to the
  beginning or end of a command line
• You can also jump forward or back, character by
  character, or word by word
• You can turn off the enhanced editing features by
  typing terminal no editing at either the user
  EXEC or the privileged EXEC prompts
• You can turn on terminal editing by typing
  terminal editing

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Enhanced Editing (continued)
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Command History

• Command history
• Allows you to retrieve previously typed commands
• You can see up to 10 previously typed commands by
  typing show history
• From either the user EXEC or privileged EXEC mode
• To modify the number of commands stored by the
  router, you can use the terminal command
• Up to 256 previous commands
• Type terminal history size n

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Configuring Router Identification

• Router host name
• Default host name is router
• To set the router host name, type hostname
  followed by the name that you want to set
• Configure a banner
• A banner is a message that you can configure to
  display each time someone attempts to log in to
  the router
• Enter global configuration mode by typing config
  t
• Then type banner motd, followed by a space and a
  delimiting character

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Configuring Router Identification (continued)
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Configuring Router Identification (continued)
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Configuring Router Identification (continued)

• Configure an interface description
• Use the description command
• The interface description helps you remember
  which network the interface services

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Configuring the Time and Date

• Use the clock set command in enable mode to
  configure the time
• You must be in global configuration mode to
  configure the time zone

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Router Components

• This section discusses the hardware elements of
  the router
• ROM
• Flash memory
• NVRAM
• RAM/DRAM
• Interfaces

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ROM

• Read-only memory (ROM)
• Loads the bootstrap program that initializes the
  routers basic hardware components
• Not modified during normal operations, but it can
  be upgraded with special plug-in chips
• The content of ROM is maintained even when the
  router is rebooted
• The ROM monitor firmware runs when the router is
  turned on or rebooted

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Flash Memory

• Flash memory
• A type of erasable, programmable, read-only
  memory (EPROM)
• Not typically modified during normal operations
• However, it can be upgraded or erased when
  necessary
• The content of flash memory is maintained even
  when the router is rebooted
• Flash memory
• Contains the working copy of the current Cisco
  IOS
• Is the component that initializes the IOS for
  normal router operations

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NVRAM

• Nonvolatile random access memory (NVRAM)
• A special type of RAM that is not cleared when
  the router is rebooted
• The startup configuration file for the router is
  stored in NVRAM by default
• This is the first file created by the person who
  sets up the router
• The Cisco IOS uses the configuration file in
  NVRAM during the router boot process

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RAM/DRAM

• Random access memory (RAM)
• Also known as dynamic random access memory (DRAM)
• A volatile hardware component
• Its information is not maintained in the event of
  a router reboot
• Changes to the routers running configuration
  take place in RAM/DRAM

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RAM/DRAM (continued)

• The IOS contains commands to view each of the
  routers components
• show running-config
• show memory
• show buffers
• show startup-config
• Copy running-config startup-config
• Abbreviated as Copy run start

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Interfaces

• A router can ship with a variety of configurable
  interfaces
• A common interface is Ethernet0
• Other types of interfaces include
• Token Ring
• Basic Rate Interface (BRI)
• Asynchronous Transfer Mode (ATM)
• Fiber Distributed Data Interface (FDDI)
• Channel Interface Processor (CIP) for Systems
  Network Architecture (SNA)
• High-Speed Serial Interface (HSSI)

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Summary

• Cisco routers use the Cisco IOS to provide an
  interface for network operators and
  administrators
• The first mode entered is user EXEC (routergt
  prompt) and the next mode is privileged EXEC
  (router prompt)
• In user EXEC, you can accomplish basic tasks
• To actually configure the router, privileged EXEC
  mode must be accessed
• The privileged EXEC mode is often called enable
  mode

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Summary (continued)

• The enable, enable secret, and VTY passwords are
  set during initial configuration if the system
  configuration dialog is used
• When configured, the enable secret password
  supersedes the enable password
• The components of a router include ROM, flash
  memory, NVRAM, RAM/DRAM, and interfaces
• ROM stores a limited version of the Cisco IOS and
  routines for checking the hardware during system
  boot

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Summary (continued)

• Flash memory stores the Cisco IOS that is loaded
  by default during system boot
• NVRAM stores the startup copy of the router
  configuration file that is loaded by default
  during system boot
• RAM/DRAM stores the working copy (running
  configuration) of the router configuration
• Interfaces provide connectivity to various types
  of LANs and WANs