Connecting and Logging In to a Switch

Connecting and Logging In to a Switch
The new range of Cisco switches—the 2950 and 3550—run a version of IOS. This makes configuring
the switch very similar to configuring a router. The 4000 series is still set based, which
means you use the command set to configure the router. Throughout the rest of this book, we’ll
show you commands for these switches.
As a general guideline, you would be expected to use the 2950 as an access layer switch
(because of its cheap per-port cost) and then utilize the more powerful 3550 at the distribution
layer. Although these are only rough guidelines, the 3550 does support an internal routing
option, which gives it the additional features essential in a modern distribution switch, and the
2950 has a number of different port types and densities, which provide relatively cheap connections
for desktop PCs.
There are two types of operating systems that run on Cisco switches:
IOS based You can configure the Catalyst 2950 and 3550 switches from a command-line
interface (CLI) that is almost identical to the one used on Cisco routers. The only differences are
some of the commands, which are switch-specific.
Set based Uses older, set-based CLI configuration commands. The current Cisco switches that
use the set-based commands are the 4000 and the 6000 series.
The shelf life of CatOS—the set-based operating system installed on older
switches such as the 4000, 5000, and 6000 series—is now very short. Although
Cisco has not publicly stated that it is not included in the current exam, my feeling
is that questions on CatOS will become fewer until they gradually disappear.
I have left CatOS configuration examples and questions in this revision of
the book because you may come across them either during the exam or “in the
wild,” but I would advise you to check the Cisco website regularly for information
regarding its demise.