• 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
    • Lab Activity Lab Exercise: Using Router show Commands This lab is to become familiar with the basic router show commands. Lab Activity e-Lab Activity: On by Default This lab is to view the basic configuration and interface details to see the router defaults. Web Links Cisco IOS Command Reference, Release 12.2 http://www.cisco.com/en/US/products/sw/ iosswrel/ps1835/products_product_ index09186a00800f2604.html#31928
    Content 3.1 Configuring a Router 3.1.5 Configuring a serial interface A serial interface can be configured from the console or through a virtual terminal line. To configure a serial interface follow these steps:
    1. Enter global configuration mode
    2. Enter interface mode
    3. Specify the interface address and subnet mask
    4. Set clock rate if a DCE cable is connected. Skip this step if a DTE cable is connected.
    5. Turn on the interface
    Each connected serial interface must have an IP address and subnet mask if the interface is expected to route IP packets. Configure the IP address using the following commands: Router(config)#interface serial 0/0
    Router(config-if)#ip address <ip address> <netmask> 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. On serial links that are directly interconnected, as in a lab environment, one side must be considered a DCE and provide a clocking signal. 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. However, some bit rates might not be available on certain serial interfaces depending of their capacity. By default, interfaces are turned off, or disabled. To turn on or enable an interface, the command no shutdown is entered. If an interface needs to be administratively disabled for maintenance or troubleshooting the command shutdown is used to turn off the interface. In the lab environment, the clockrate setting that will be used is 56000. 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 Lab Activity Lab Exercise: Configuring a Serial Interface In this lab, the student will configure a serial interface on the Lilongwe and DarEsSalaam routers so they can communicate. Lab Activity e-Lab Activity: Configuring a Serial Interface This lab is to access the router command-line interface and activate privileged level configuration options. Web Links Configuration http://www.cisco.com/en/US/products/hw/ modules/ps3129 /products_tech_ note09186a00800b1502.shtml#fifth
    Content 3.1 Configuring a Router 3.1.6 Executing adds, moves, and changes If a configuration requires modification, go to the appropriate mode and enter the proper command. For example, if an interface must be enabled, enter global configuration mode, enter interface mode, and issue the command no shutdown. To verify changes, use the show running-config command. This command will display the current configuration. If the variables displayed are not what was intended, the environment can be corrected by doing one or more of the following: To save the configuration variables to the startup configuration file in NVRAM, enter the following command at the privileged EXEC prompt: Router#copy running-config startup-config Lab Activity Lab Exercise: Making Configuration Changes This lab is to configure some basic router settings and bring interfaces up and down.
    Content 3.1 Configuring a Router 3.1.7 Configuring an Ethernet interface An Ethernet interface can be configured from the console or a virtual terminal line. Each Ethernet interface must have an IP address and subnet mask if the interface is expected to route IP packets. To configure an Ethernet interface follow these steps:
    1. Enter global configuration mode
    2. Enter interface configuration mode
    3. Specify the interface address and subnet mask
    4. Enable the interface
    By default, interfaces are turned off, or disabled. To turn on or enable an interface, the command no shutdown is entered. If an interface needs to be administratively disabled for maintenance or troubleshooting the command shutdown is used to turn off the interface. Lab Activity Lab Exercise: Configuring an Ethernet Interface This lab is to configure an Ethernet interface on the router with an IP address and a subnet mask. Lab Activity e-Lab Activity: Configuring an Ethernet Interface In this lab, the students will configure an Ethernet interface on the router. Web Links interface fastethernet Command Syntax Description http://www.cisco.com/en/US/products/sw/ iosswrel/ps1835/products_command_reference_ chapter09186a00800874b0.html#1017394
    Content 3.2 Finishing the Configuration 3.2.1 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. 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. In order to manage a network, there must be a centralized support standard. Configuration, security, performance, and other issues must be adequately addressed for the network to function smoothly. Creating standards for network consistency helps reduce network complexity, the amount of unplanned downtime, and exposure to events that may have an impact on network performance.
    Content 3.2 Finishing the Configuration 3.2.2 Interface descriptions An interface description should be used to identify important information such as a distant router, a circuit number, or a specific network segment. A description of an interface can help a network user remember specific information about the