IOS on Switches

All Cisco switches use either IOS or CatOS as the user interface. IOS-enabled switches include the 2900XL, 2950, 3550, and 1900 series devices. These devices use the same IOS interface that routers use, with a few slight differences.

On the 1900 series (which is at the end of its product lifecycle), you must take an extra step to get to the IOS interface, navigating through a menu prompt. You press K to get to the IOS interface. For example:

 Catalyst 1900 Management Console
 Copyright (c) Cisco Systems, Inc. 1993-1998
 All rights reserved.
 Enterprise Edition Software
 Ethernet Address: 00-B0-64-A7-85-00

 PCA Number: 73-3121-04
 PCA Serial Number: FAB040231K4
 Model Number: WS-C1924-A
 System Serial Number: FAB0403V0KG
 Power Supply S/N: PHI03430376
 PCB Serial Number: FAB040231K4,73-3121-04
 -------------------------------------------------

 1 user(s) now active on Management Console.

 User Interface Menu

 [M] Menus
 [K] Command Line

 Enter Selection: K


 CLI session with the switch is open.
 To end the CLI session, enter [Exit].

 switch1>

Many higher-end Catalyst series switches (4000, 5000, 5500, 6000, 6500) still run the CatOS (Catalyst OS). This interface is only vaguely similar to IOS. Like IOS, CatOS has an enable mode and show commands. However, that's where the similarities end. The CatOS uses set commands to configure the router. For example:

 switch> (enable) set system name switch2
 switch2> (enable) set ip route 0.0.0.0/0.0.0.0 172.16.1.3
 switch2> (enable)

As you can see, the enable mode is a bit different. However, most of the commands will be familiar although their syntax and naming is totally different in most places. The good news is that Cisco is working on IOS capability for the newer models of CatOS switches. For example, the 6500 series can be configured with your choice of either CatOS or IOS. (You can easily guess which choice I would make.)