Subnetting

Todd Lammle

• Publisher: Sybex
• Year: 2017
• ISBN:
  9781119472766
• Edition: 1
• Topic: Informatik
• Subtopic: Zertifizierungsleitfäden in der Informatik

Master the fundamental concept at the heart of professional networking

Subnetting is the aspiring network professional's guide to the concepts and practices at the core of the field. By dividing a single physical network into smaller subnetworks, you gain greater control of performance, access, and security. While the concept is simple, the actual practice is complex—yet it is an essential skill for networking professionals, and a major skill tested on the CCENT and CompTIA Network+ exams. This book shows you everything you need to know about constructing IP addresses, VSLM, and route summarization to help you build your skill set on a strong foundation.

The IPv4 address has 32 bits available, which can be divided into host ID and network ID; the number of bits assigned to the network ID determines the balance between total subnetworks and devices allowed—the trick is determining the most efficient balance for a particular network. Subnetting allows you to borrow bits from the host to allow for more networks, and subnet masks are used to determine switching and routing priority. This book delves into the mechanisms and practices you need to know, including networking fundamentals, rules of IP addresses, supernetting, variable length subnet mask, IPv6, and more:

• Master the fundamental topic at the heart of the Cisco Certified Entry Networking Technician and CompTIA Network+ certifications
• Improve network performance using subnetworks to avoid high-usage "clogs"
• Utilize network partitioning to confine breaches or viruses and improve security
• Construct efficient solutions to problems of allocation and range

With clear guidance from an industry expert and a practical perspective geared toward real-world situations, Subnetting offers an outstanding introduction to this essential foundational concept.

Easy Subnetting

I’ll open this book by telling you how to subnet an IP network—an indispensably crucial skill that’s central to mastering networking in general! Forewarned is forearmed, so prepare yourself because being able to subnet quickly and accurately is pretty challenging and you’ll need time to practice what you’ve learned to really nail it. So be patient and don’t give up on this key aspect of networking until your skills are seriously sharp. I’m not kidding—this book is so important you should really just graft it into your brain!

So be ready because we’re going to hit the ground running and thoroughly cover IP subnetting from the very start. And though I know this will sound weird to you, you’ll be much better off if you just try to forget everything you’ve learned about subnetting before reading this book—especially if you’ve been to an official Cisco or Microsoft class! I think these forms of special torture often do more harm than good and sometimes even scare people away from networking completely. Those that survive and persevere usually at least question the sanity of continuing to study in this field. If this is you, relax, breathe, and know that you’ll find that the way I tackle the issue of subnetting is relatively painless because I’m going to show you a whole new, much easier method to conquer this monster!

After working through this book, and I can’t say this enough, after working through the extra study material at the end as well, you’ll be able to tame the IP addressing/subnetting beast—just don’t give up! I promise that you’ll be really glad you didn’t. It’s one of those things that once you get it down, you’ll wonder why you used to think it was so hard!

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To find up-to-the minute updates for this book, please see www.lammle.com/ccna or the book’s web page at www.sybex.com/go/ccna.

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Subnetting Basics

Take a look at the network that’s shown in Figure 1.

Figure 1 One network

You’re probably aware that having one large network is not a good thing. But how would you fix the out-of-control problem that Figure 1 illustrates? Wouldn’t it be nice to be able to break up that one, huge network address and create four manageable networks from it? You betcha it would, but to make that happen, you would need to apply the infamous trick of subnetting because it’s the best way to break up a giant network into a bunch of smaller ones. Take a look at Figure 2 and see how this might look.

Figure 2 Multiple networks connected together

What are those 192.168.10.x addresses shown in the figure? Well that is what this ...