Anatomy of a Router

I am of the opinion that all routers are female. Must be. Look
at the relatively high male to female tech ratio in IT. Gotta be the routers.
Obviously, I could be wrong, but a router's anatomy is interesting all the same.
Let's take a closer look.

The first thing you should know about a router is she has a lot in common
with the PC on your desk. Sure, it's got some neat toys but a router (Cisco
or otherwise) is nothing more than a very specialized network computer. Just
looking at the two, especially side by side, and they look very different.

Looks CAN be deceiving. OK, they don't have the same external
components but, on the functional level, routers and computers are very
similar. In fact, a server can be set up to act as a router. This goes back
to the early days of networking, when ordinary computers performed all
routing. The computers were, and still can be, equipped with at least two

NICs, each going out to a different segment. A routing program would
have to be loaded onto the computer and this program would operate alongside
all its other applications. Click

here for routing setup in Windows NT and

here for routing setup in Window 2000.

Another point of similarity between routers and computers are their boot
sequences.

Let's look at them:

Computer Boot Sequence

1) POST

2) System initialization, CMOS and BIOS check.

3) Load the Disk Operating System

4) Load configurations (config.sys)

5) Run programs at startup (autoexec.bat)

6) Load Windows

Router Boot Sequence


1) The router performs the POST.

2) The bootstrap searches for and loads the Cisco IOS software.

3) The IOS software looks in NVRAM for a valid configuration file.

4) If there is a valid configuration file in NVRAM, then this file will be
loaded and executed.

Not exactly the same but the similarities are there. Like a PC, a router has
unique hardware and an operating system. Both PC and router have a
CPU,
memory, and
input/output ports. Like a PC, a router boots by loading its OS into
memory, and reading a configuration file. Of course, the differences are
rather glaring. A router has no keyboard, mouse or monitor and must be
accessed via terminal or a PC acting as a terminal..

I don't want you to get bogged down in router compared to PC, except to
realize that they are similar and that a router is just a very specialized
network computer. Having said that, and just BTW, here are two excellent
articles on the computer boot sequence:


http://www.mossywell.com/boot-sequence/
http://www.qvctc.commnet.edu/pcguide/boot.html