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IP Subnetting: Practical Subnet Design and Address Determination Example
When educators ask students what
they consider to be the most confusing aspect in learning about networking,
many say that it is IP address subnetting. While subnetting isn't all
that difficult in concept, it can be a bit mind-boggling in part due
to the manipulations of binary numbers required. Many people understand
the ideas behind subnetting but find it hard to follow the actual steps
required to subnet a network.
For this reason, even though I
explained the concepts behind subnetting in detail in the previous section,
I felt it would be valuable to have another section that provides a
step-by-step look at how to perform custom subnetting. This section
divides subnetting into five relatively straight-forward stages that
cover determining requirements, making the design decision of how many
bits to use for subnet ID and host ID, and then determining important
numbers such as the subnet mask, subnet addresses and host addresses.
My focus in this section is on showing
the practical how of subnetting. The topics here work through
two examples using a Class B and a Class C sample network to show you
how subnetting is done, and I am explicit in showing how everything
is calculated. This means the section is a bit number-heavy.
Also, I try not to duplicate conceptual issues covered in the previous
section, though a certain amount of overlap does occur. Overall, if
you are not familiar with how subnetting works at all, you will want
that section first. I do refer to topics
in that section where appropriate, especially the summary
tables. Incidentally, I only cover conventional
subnetting here, not VLSM.
This section may serve as a useful
refresher or summary of subnetting for someone who is already familiar
with the basics but just wants to review the steps performed in subnetting.
Again, always bear in mind that subnetting is based on the older classful
IP addressing scheme, and today's Internet
Background Information: If you are not familiar with binary numbers, binary-to-decimal conversion and masking, and you didn't take my advice in preceding sections to brush up on these concepts using the background explanation of computational math, you really want to do that now.
Note: If in reading this section you find yourself wanting to do binary-to-decimal conversions or binary math, remember that most versions of Windows (and many other operating systems) have a calculator program that incorporates scientific functions.
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Table Of Contents - Contact Us
The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005
© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
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