mode are limited to those that change terminal settings, perform basic tests, and display system information. Figure describes the show commands that are available in User EXEC mode. The enable command is used to change from User EXEC mode to Privileged EXEC mode. Privileged EXEC mode is also recognized by its prompt, which ends in a pound-sign character (#). The Privileged EXEC mode command set includes those commands allowed in User EXEC mode, as well as the configure command. The configure command allows other command modes to be accessed. Because these modes are used to configure the switch, access to Privileged EXEC mode should be password protected to prevent unauthorized use. If the system administrator has set a password, then users are prompted to enter the password before being granted access to Privileged EXEC mode. The password does not appear on the screen, and is case sensitive.
Content 6.2 Configuring the Switch 6.2.1 Verifying the Catalyst switch default configuration When powered up for the first time, a switch has default data in the running configuration file. The default hostname is Switch. No passwords are set on the console or virtual terminal (vty) lines. A switch may be given an IP address for management purposes. This is configured on the virtual interface, VLAN 1. By default, the switch has no IP address. The switch ports or interfaces are set to auto mode , and all switch ports are in VLAN 1. VLAN 1 is known as the default management VLAN. The flash directory by default, has a file that contains the IOS image, a file called env_vars, and a sub-directory called html. After configuring the switch, it may contain a config.text file, and a VLAN database. The flash directory has no VLAN database file, vlan.dat, and shows no saved configuration file, config.text. The IOS version and the configuration register settings can be verified with the show version command. In this default state, the switch has one broadcast domain and can be managed or configured through the console port using the CLI. The Spanning-Tree Protocol is also enabled, and allows the bridge to construct a loop-free topology across an extended LAN. For small networks, the default configuration may be sufficient. The benefits of better performance with microsegmentation are obtained immediately. Lab Activity Lab Exercise: Verifying Default Switch Configuration In this lab, the student will investigate the default configuration of a 2900 series switch. Lab Activity e-Lab Activity: Basic Switch Operation In this lab, the student will look at the configuration of a 2950 switch. Web Links Features, default Settings, and Descriptions http://www.cisco.com/univercd/cc/td/doc/ product/lan/ cat2950/2950_wc/ scg/ scg_mgmt.htm#xtocid111203
Content 6.2 Configuring the Switch 6.2.2 Configuring the catalyst switch A switch may already be preconfigured and only passwords may need to be entered for the user EXEC, enable, or privileged EXEC modes. Switch configuration mode is entered from privileged EXEC mode. In the CLI, the default privileged EXEC mode is Switch#. In User EXEC mode the prompt will be Switch>. The following steps will ensure that a new configuration will completely overwrite any existing configuration: Security, documentation, and management are important for every internetworking device. A switch should be given a hostname, and passwords should be set on the console and vty lines. To allow the switch to be accessible by Telnet and other TCP/IP applications, IP addresses and a default gateway should be set. By default, VLAN 1 is the management VLAN. In a switch-based network, all internetworking devices should be in the management VLAN. This will allow a single management workstation to access, configure, and manage all the internetworking devices. The Fast Ethernet switch ports default to auto-speed and auto-duplex. This allows the interfaces to negotiate these settings. When a network administrator needs to ensure an interface has particular speed and duplex values, the values can be set manually. Intelligent networking devices can provide a web-based interface for configuration and management purposes. Once a switch is configured with an IP address and gateway, it can be accessed in this way. A web browser can access this service using the IP address and port 80, the default port for http. The HTTP service can be turned on or off, and the port address for the service can be chosen. Any additional software such as an applet, can be downloaded to the browser from the switch. Also, the network devices can be managed by a browser based graphical user interface (GUI). Lab Activity Lab Exercise: Basic Switch Configuration In this lab, the student will configure a switch with a name and an IP address. Lab Activity e-Lab Activity: Basic Switch Configuration In this lab, the student will configure a 2950 switch. Web Links Using the Command-Line Interface http://www.cisco.com/univercd/cc/ td/doc/product/lan/ cat2950/12111ea1/ scg/swcli.htm
Content 6.2 Configuring the Switch 6.2.3 Managing the MAC address table Switches learn the MAC addresses of PCs or workstations that are connected to their switch ports by examining the source address of frames that are received on that port. These learned MAC addresses are then recorded in a MAC address table. Frames having a destination MAC address that has been recorded in the table can be switched out to the correct interface. To examine the addresses that a switch has learned, enter the privileged EXEC command show mac-address–table. A switch dynamically learns and maintains thousands of MAC addresses. To preserve memory and for optimal operation of the switch, learned entries may be discarded from the MAC address table. Machines may have been removed from a port, turned off, or moved to another port on the same switch or a different switch. This could cause confusion in frame forwarding. For all these reasons, if no frames are seen with a previously learned address, the MAC address entry is automatically discarded or aged out after 300 seconds. Rather than wait for a dynamic entry to age out, the administrator has the option to use the privileged EXEC command clear mac-address-table. MAC address entries that an administrator has configured can also be removed using this command. Using this method to clear table entries ensures that invalid addresses are removed immediately. Lab Activity Lab Exercise: Managing the MAC Address Table In this lab, the student will create a basic switch configuration and manage the MAC table. Lab Activity e-Lab Activity: Managing the MAC Address Tables In this lab, the student will observe and clear the MAC address table. Web Links Managing the MAC Address Table http://www.cisco.com/univercd/cc/ td/doc/product/ lan/cat2950/12111ea1/ scg/swadmin.htm#xtocid65
Content 6.2 Configuring the Switch 6.2.4 Configuring static MAC addresses It may be decided that it is desirable for a MAC address to be permanently assigned to an interface. The reasons for assigning a permanent MAC address to an interface include: To set a static MAC address entry for a switch: Switch(config)#mac-address-table static <mac-address of host> interface FastEthernet <Ethernet numer> vlan To remove this entry use the no form of the command: Switch(config)#no mac-address-table static <mac-address of host> interface FastEthernet <Ethernet number> vlan