Table 2.8: DB−25−to−DB−9 connector pinouts.

Switch IOSs

Three types of Cisco operating systems are in use:

∙Set/Clear command interface—Found on models of the Catalyst 2926, 2926G, 2948G, 2980G, 4000, 5000, 5500, 6000, and 6500 series of switches. They are called Set/Clear because most commands on the switches start with set, clear, or show.

∙Cisco IOS−based Command Line Interface—Most closely resembles a Cisco router’s IOS Command Line Interface. This interface is found on Catalyst 1900EN, 2820, 2900 XL, 8500, and 12000 series models.

∙Menu−driven—Found exclusively on the Catalyst 1900SE, 2820SE, 3000, 3100, and 3200 series switches.

You have to do very little in order to get a Cisco switch to work. By default, the Set/Clear command set switches and the Cisco CLI IOS interface switches have the following default attributes:

∙The prompt name is set to Console>.

∙No hostname is configured.

∙No passwords are set.

∙All ports default to VLAN1.

∙The console port has no IP information.

∙No contact name or location information is defined.

∙RMON is disabled.

∙SNMP traps are disabled.

∙SNMP community strings are set Public for read−only, Private for read−write, and Secret for read−write−all access.

∙VLAN Trunking Protocol (VTP) mode is set to Server.

∙No VTP domain or password is configured.

∙All VLANs are eligible for trunking.

∙Inter−Switch Link (ISL) defaults to Auto.

The IOS Configuration Modes

The CLI of IOS−based switches is similar to that of IOS−based routers. Commands can be recalled by using the up or down arrows or by using a combination of Ctrl or Esc sequences to perform certain editing functions in the command−line history buffers.

On an IOS−based switch, you can access many command modes to enter commands. Here are some of the more important modes:

∙EXEC mode—When you log in to a switch, you are automatically in User EXEC command mode. The EXEC commands are a subset of those available at the Privileged level. In general, EXEC commands allow you to test connectivity, perform basic tests, and list system information.

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