3.3 Important Cisco IOS Features
3.3.3 Show commands on a set command-based switch

To view configurations on a set command-based switch, use the show command. Figures annotate a simple Supervisor module configuration file displayed through the show config command. Some configuration lines are editorially deleted because they are redundant and needlessly take up space. The remaining portion of the file enables you to see the general organization of the configuration file.

Note in Figures that the file collates in logical sections. First, the Catalyst switch writes any globally applicable configuration items such as passwords, Simple Network Management Protocol (SNMP) parameters, system variables, and so forth. Then, it displays configurations for each module installed. Note that the module configuration files refer to spanning tree and VLAN assignments. Further, it does not display any details about other functions within the module. For example, a route switch module (RSM) is installed in module 5 of this switch. Although this is a router module, it attaches to a virtual bridge port internally. The Catalyst switch displays the bridge attachment parameters, but not the RSM configuration lines. To see module-specific configurations, you need to access them with the command session module_number followed by the appropriate show command for the module.

Other show commands display item-specific details. For example, to look at the current configuration for the in-band (sc0) interface, out-of-band management Ethernet (me1) interface, and SLIP (sl0) interface, use the show interface command, as demonstrated in Figure .

Another useful show command displays the modules loaded in your switch (see Figure ). The output in Figure displays details about the model number and description of the modules in each slot. The second block of the output tells you what Media-Access-Control (MAC) addresses are associated with each module. Notice that the Supervisor module reserves 1024 MAC addresses. Many of these addresses support spanning-tree operations, but other processes are also involved. Module 3, the 24-port Ethernet module, reserves 24 MAC addresses, one for each port. These addresses also support spanning tree because they are the values used for the port ID in the spanning tree convergence algorithm. The third block of the display offers details regarding the Supervisor module.