Semester 2 Module 3 Configuring a Router

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Semester 2 Module 3 Configuring a Router

• Yuda college of business
• James Chen
• ydjames_at_ydu.edu.tw

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Outline

• Configuring a Router
• Finishing the Configuration

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CLI command modes

• All command-line interface (CLI) configuration
  changes to a Cisco router are made from the
  global configuration mode.
• Other more specific modes are entered depending
  upon the configuration change that is required,
  but these specific modes are all subsets of the
  global configuration mode.
• Note The prompt changes to indicate that the
  router is now in global configuration mode.

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• These are just a few of the modes that can be
  entered from global configuration mode
• Interface mode
• Line mode
• Router mode
• Subinterface mode
• Controller mode

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• Typing exit from one of these specific
  configuration modes will return the router to
  global configuration mode.
• Pressing Ctrl-Z leaves the configuration modes
  completely and returns the router to privileged
  EXEC mode.

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Configuring a router name

• A router should be given a unique name as one of
  the first configuration tasks.
• This task is accomplished in global configuration
  mode using the following commands
• Router(config)hostname Tokyo
• Tokyo(config)
• As soon as the Enter key is pressed, the prompt
  changes from the default host name (Router) to
  the newly configured host name, which is Tokyo in
  the example.

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Configuring router passwords

• Passwords
• virtual terminal lines
• console line
• privileged EXEC mode

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• The following commands are used to set an
  optional but recommended password on the console
  line
• Router(config)line console 0
• Router(config-line)password ltpasswordgt
• Router(config-line)login

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• The following commands are used to set the
  password on the VTY lines
• Router(config)line vty 0 4
• Router(config-line)password ltpasswordgt
• Router(config-line)login

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• The enable password and the enable secret are
  used to restrict access to the privileged EXEC
  mode.
• The enable password is only used if the enable
  secret has not been set.
• It is recommended that the enable secret always
  be set and used because it is encrypted while the
  enable password is not encrypted.

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• These are the commands that are used to set the
  enable passwords
• Router(config)enable password ltpasswordgt
• Router(config)enable secret ltpasswordgt

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• This command is used to encrypt passwords in
  configuration output
• Router(config)service password-encryption
• The service password-encryption command applies a
  weak encryption to all unencrypted passwords.
• The enable secret ltpasswordgt command uses a
  strong MD5 algorithm for encryption.

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Examining the show commands

• There are many show commands that can be used to
  examine the contents of files in the router and
  for troubleshooting.
• In both privileged EXEC and user EXEC modes, the
  command show ? provides a list of available show
  commands.

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• show interfaces Displays all the statistics for
  all the interfaces on the router. To view the
  statistics for a specific interface, enter the
  show interfaces command followed by the specific
  interface and port number. For example
• Routershow interfaces serial 0/1
• show controllers serial Displays
  information-specific to the interface hardware
• show clock Shows the time set in the router
• show hosts Displays a cached list of host names
  and addresses
• show users Displays all users who are connected
  to the router

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• show history Displays a history of commands
  that have been entered
• show flash Displays information about flash
  memory and what IOS files are stored there
• show version Displays information about the
  router and the IOS that is running in RAM
• show ARP Displays the ARP table of the router
• show protocol Displays the global and interface
  specific status of any configured Layer 3
  protocols
• show startup-configuration Displays the saved
  configuration located in NVRAM
• show running-configuration Displays the
  configuration currently running in RAM

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Configuring a serial interface

• To configure a serial interface follow these
  steps
• Enter global configuration mode
• Enter interface mode
• Specify the interface address and subnet mask
• Set clock rate if a DCE cable is connected. Skip
  this step if a DTE cable is connected.
• Turn on the interface

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• Configure the IP address using the following
  commands
• Enter global configure terminal configuration
  mode by entering the command.
• Router(config)interface serial 0/0
• Router(config-if)ip address ltip addressgt
  ltnetmaskgt

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• Serial interfaces require a clock signal to
  control the timing of the communications.
• In most environments, a DCE device such as a CSU
  will provide the clock.
• By default, Cisco routers are DTE devices but
  they can be configured as DCE devices.

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• The clock is enabled and speed is specified with
  the clock rate command.
• The available clock rates in bits per second are
  1200, 2400, 9600, 19200, 38400, 56000, 64000,
  72000, 125000, 148000, 500000, 800000, 1000000,
  1300000, 2000000, or 4000000.

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• By default, interfaces are turned off, or
  disabled.
• To turn on or enable an interface, the command no
  shutdown is entered

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• The commands for setting a clock rate and
  enabling a serial interface are as follows
• Router(config)interface serial 0/0
• Router(config-if)clock rate 56000
• Router(config-if)no shutdown

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Executing adds, moves, and changes

• If a configuration requires modification, go to
  the appropriate mode and enter the proper
  command.
• To verify changes, use the show running-config
  command.
• To save the configuration variables to the
  startup configuration file in NVRAM, enter the
  following command at the privileged EXEC prompt
• Routercopy running-config startup-config

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Configuring an Ethernet interface

• To configure an Ethernet interface follow these
  steps
• Enter global configuration mode
• Enter interface configuration mode
• Specify the interface address and subnet mask
• Enable the interface
• By default, interfaces are turned off, or
  disabled.
• To turn on or enable an interface, the command no
  shutdown is entered.

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Outline

• Configuring a Router
• Finishing the Configuration

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Importance of configuration standards

• It is important for standards to be developed for
  configuration files within an organization.
• This allows control of the number of
  configuration files that must be maintained, how
  the files are stored, and where the files are
  stored.

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• A standard is a set of rules or procedures that
  are either widely used or officially specified.
• Without standards in an organization, a network
  could be in chaos should an interruption in
  service occur.

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Interface descriptions

• A description of an interface can help a network
  user remember specific information about the
  interface, such as what network the interface
  services.
• The description is meant solely as a comment
  about the interface.

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Configuring interface description

• Procedure steps
• Enter global configure terminal configuration
  mode by entering the command.
• Enter specific interface mode (for example
  interface Ethernet 0) interface ethernet 0.
• Enter the command description followed by the
  information that is to be displayed. For example,
  XYZ Network, Building 18.
• Exit interface mode back to privileged EXEC mode
  by using the command ctrl-Z.
• Save the configuration changes to NVRAM by using
  the command copy running-config startup-config.

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Login banners

• A login banner is a message that is displayed at
  login and is useful for conveying messages that
  affect all network users, such as notices of
  impending system shutdowns.
• Login banners can be seen by anyone.
• Therefore, careful attention should be used in
  the wording of a banner message. Welcome is an
  invitation for anyone to enter a router and is
  probably not an appropriate message.

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Configuring message-of-the-day (MOTD)

• A message-of-the-day (MOTD) banner can be
  displayed on all connected terminals.
• Enter global configuration mode to configure a
  message-of-the-day (MOTD) banner.
• Use the banner motd command, followed by a space
  and a delimiting character, such as the pound
  sign ().
• Add a message-of-the-day (MOTD) followed by a
  space and the delimiting character again.

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• Follow these steps to create and display a
  message-of-the-day
• Enter global configuration mode by using the
  command configure terminal.
• Enter the command banner motd The message of
  the day goes here .
• Save changes by issuing the command copy
  running-config startup-config.

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Host name resolution

• Host name resolution is the process that a
  computer system uses to associate a host name
  with an IP address.
• A list of host names and their associated IP
  addresses is called a host table.

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Configuring host tables

• The procedure to configure the host table
• Enter global configuration mode in the router.
• Enter the command ip host followed by the name of
  the router and all IP addresses associated with
  the interfaces on each router.
• Continue entering until all routers in the
  network are entered.
• Save the configuration to NVRAM.

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Configuration backup and documentation

• Management of device configuration includes the
  following tasks
• Listing and comparing configuration files on
  running devices
• Storage of configuration files on network servers
  
• Performing software installations and upgrades
• Configuration files should be stored as backup
  files in the event of a problem.
• Configuration files can be stored on a network
  server, on a TFTP server, or on a disk stored in
  a safe place.
• Documentation should be included with this
  offline information.

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Copying, editing, and pasting configurations

• The copy running-config tftp command can be used
  to store the current configuration on a network
  TFTP server.
• To do so, complete the following tasks
• Step 1 Enter the copy running-config tftp
  command.
• Step 2 Enter the IP address of the host where the
  configuration file will be stored.
• Step 3 Enter the name to assign to the
  configuration file.
• Step 4 Confirm the choices by answering yes each
  time.

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• A configuration file stored on one of the network
  servers can be used to configure a router.
• To do so, complete the following tasks
• Enter configuration mode by entering the copy
  tftp running-config command
• At the system prompt, select a host or network
  configuration file.
• At the system prompt, enter the name of the
  configuration file or accept the default name.

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