Understanding Cisco Networking Technologies, Volume 1

Volume 1 Exam 200-301

Todd Lammle

• Éditeur: Sybex
• Année: 2019
• ISBN:
  9781119659037
• Édition: 1
• Sujet: Computer Science
• Sous-sujet: Certification Guides in Computer Science

Leading Cisco authority Todd Lammle helps you gain insights into the new core Cisco network technologies

Understanding Cisco Networking Technologies is an important resource for those preparing for the new Cisco Certified Network Associate (CCNA) certification exam as well as IT professionals looking to understand Cisco's latest networking products, services, and technologies. Written by bestselling author and internationally recognized Cisco expert Todd Lammle, this in-depth guide provides the fundamental knowledge required to implement and administer a broad range of modern networking and IT infrastructure.

Cisco is the worldwide leader in network technologies—80% of the routers on the Internet are Cisco. This authoritative book provides you with a solid foundation in Cisco networking, enabling you to apply your technical knowledge to real-world tasks. Clear and accurate chapters cover topics including routers, switches, controllers and other network components, physical interface and cabling, IPv6 addressing, discovery protocols, wireless infrastructure, security features and encryption protocols, controller-based and software-defined architectures, and more. After reading this essential guide, you will understand:

• Network fundamentals
• Network access
• IP connectivity and IP services
• Security fundamentals
• Automation and programmability

Understanding Cisco Networking Technologies is a must-read for anyone preparing for the new CCNA certification or looking to gain a primary understanding of key Cisco networking technologies.

Chapter 1
Internetworking

Welcome to the exciting world of internetworking! This chapter is essentially an internetworking review, focusing on how to connect networks together using Cisco routers and switches. As a heads up, I’ve written it with the assumption that you have at least some basic networking knowledge.

Let’s start by defining exactly what an internetwork is: You create an internetwork when you connect two or more networks via a router and configure a logical network addressing scheme with a protocol such as IP or IPv6.

I’m also going to dissect the Open Systems Interconnection (OSI) model and describe each part of it to you in detail because you really need comprehensive knowledge of it. Understanding the OSI model is key to the solid foundation you’ll need to build upon with the more advanced Cisco networking knowledge gained down the line.

The OSI model has seven hierarchical layers that were developed to enable different networks to communicate reliably between disparate systems. Since this book is centering upon all things CCNA, it’s crucial for you to understand the OSI model as Cisco sees it, so that’s how I’ll be presenting the seven layers to you.

To find your included bonus material, as well as Todd Lammle videos, practice questions and hands-on labs, please see www.lammle.com/ccna.

Internetworking Basics

Before exploring internetworking models and the OSI model’s specifications, you need to grasp the big picture and the answer to this burning question: Why is it so important to learn Cisco internetworking anyway?

Networks and networking have grown exponentially over the past 20 years, and understandably so. They’ve had to evolve at light speed just to keep up with huge increases in basic, mission-critical user needs (e.g., the simple sharing of data and printers) as well as greater burdens like multimedia remote presentations, conferencing, and the like. Unless everyone who needs to share network resources is located in the same office space, which is increasingly rare, the challenge is to connect relevant networks so all users can share the wealth of whatever services and resources are required, on site or remotely.

Figure 1.1 shows a basic local area network (LAN) that’s connected using a hub, which is basically just an antiquated device that connects wires together. Keep in mind that a simple network like this would be considered one collision domain and one broadcast domain. No worries if you have no idea what I mean by that because we’ll go over that soon. I’m going to talk about collision and broadcast domains enough to make you dream about them!

Figure 1.1 A very basic network

Things really can’t get much simpler than this. And yes, though you can still find this configuration in some home networks, even many of those as well as the smallest business networks are more complicated today. As we move through this book, I’ll just keep building upon this tiny network a bit at a time until we arrive at some really nice, robust, and current network designs—the types that will help you get your certification and a job!

But as I said, we’ll get there one step at a time, so let’s get back to the network shown in Figure 1.1 with this scenario: Bob wants to send Sally a file, and to complete that goal in this kind of network, he’ll simply broadcast that he’s looking for her, which is basically just shouting out over the network. Think of it like this: Bob walks out of his house and yells down a street called Chaos Court in order to contact Sally. This might work if Bob and Sally were the only ones living there, but not so much if it’s crammed with homes and all the others living there are always hollering up and down the street to their neighbors just like Bob. Nope, Chaos Court would absolutely live up to its name, with all those residents going off whenever they felt like it—and believe it or not, our networks actually still work this way to a degree! So, given a choice, would you stay in Chaos Court, or would you pull up stakes and move on over to a nice new modern community called Broadway Lanes, which offers plenty of amenities and room for your home plus future additions all on nice, wide streets that can easily handle all present and future traffic? If you chose the latter, good choice…so did Sally, and she now lives a much quieter life, getting letters (packets) from Bob instead of a headache!

The scenario I just described brings me to the basic point of what this book and the Cisco certification objectives are really all about. My goal of showing you how to create efficient networks and segment them correctly in order to minimize all the chaotic yelling and screaming going on in them is a universal theme throughout my Cisco series books. It’s just inevitable that you’ll have to break up a large network into a bunch of smaller ones at some point to match a network’s equally inevitable growth, and as that expansion occurs, user response time simultaneously dwindles to a frustrating crawl. But if you master the vital technology and skills I have in store for you in this series, you’ll be well equipped to rescue your network and its users by creating an efficient new network neighborhood to give them key amenities like the bandwidth they need to meet evolving demands.

And this is no joke; most of us think of growth as good and it can be. But as many experience daily when commuting to work, school, etc., it can also mean your LAN’s traffic congestion can reach critical mass and grind to a halt! Again, the solution to this problem begins with breaking up a massive network into a number of smaller ones—something called network segmentation. This concept is a lot like planning a new community or modernizing an existing one. More streets are added, complete with new intersections and traffic signals, plus post offices are built with official maps documenting all those street names and directions on how to get to each. You’ll need to effect new laws to keep order to it all and provide a police station to protect this nice new neighborhood as well. In a networking neighborhood environment, all of this infrastructure is managed using devices like routers, switches, and bridges.

So let’s take a look at our new neighborhood now…. Because the word has gotten out, many more hosts have moved into it, so it’s time to upgrade that new high-capacity infrastructure that we promised to handle the increase in population. Figure 1.2 shows a network that’s been segmented with a switch, making each network segment that connects to the switch its own separate collision domain. Doing this results in a lot less yelling!

Figure 1.2 A switch can break up collision domains.

This is a great start, but I really want you to make note of the fact that this network is still one, single broadcast domain, meaning that we’ve really only decreased our screaming and yelling—not eliminated it. For example, if there’s some sort of vital announcement that everyone in our neighborhood needs to hear about, it will definitely still get loud! You can see that the hub used in Figure 1.2 just extended the one collisio...