TCP / IP

Todd Lammle

• Éditeur: Sybex
• Année: 2017
• ISBN:
  9781119472704
• Édition: 1
• Sujet: Informatik
• Sous-sujet: Zertifizierungsleitfäden in der Informatik

The most up-to-date, in-depth guide for TCP/IP mastery

TCP/IP is the ultimate guide to the glue that holds the Internet together. When two computers "talk" to one another, they do it through Transmission Control Protocol/Internet Protocol. Networking professionals working toward any of the CCNA-Specialty certifications must have a firm understanding of this key technology, and must stay up to date on evolving practices as new technologies emerge. Whether you're preparing for the CompTIA Network+ exam, the Cisco CCENT ICND1 exam, or just want to learn how to install, troubleshoot, and operate networks, this book tells you everything you need to know to work effectively with TCP/IP.

Expert discussion details the latest on Web protocols and new hardware, including timely information on how TCP/IP secures connectivity for blogging, vlogging, photoblogging, and social networking. From installation and configuration to intranets, extranets, virtual private networks, security measures and more, this book provides the depth and breadth of information that every aspiring networking professional needs.

• Understand the de facto standard transmission medium for computer-computer communications
• Install and configure TCP/IP and its applications on clients and servers
• Use encryption, authentication, digital certificates, signatures, and other critical security measures
• Learn the most up-to-date methods for handling new voice and mobile technologies, and more

Step-by-step instructions and clear explanations by an industry expert and networking guru bring TCP/IP down to earth and provide much-needed clarity on an essential topic. Whether or not you're preparing for certification, TCP/IP is critical knowledge for anyone working with networks, and continuous innovation means that the learning never stops. TCP/IP is an indispensable resource, packed with the latest information on this central networking concept.

Chapter 1
Introduction to TCP/IP

The Transmission Control Protocol/Internet Protocol (TCP/IP) suite was designed and implemented by the Department of Defense (DoD) to ensure and preserve data integrity as well as maintain communications in the event of catastrophic war. So it follows that if designed and implemented correctly, a TCP/IP network can be a secure, dependable and resilient one. In this chapter, I’ll cover the protocols of TCP/IP, and throughout this book, you’ll learn how to create a solid TCP/IP network with Cisco routers and switches.

We’ll begin by exploring the DoD’s version of TCP/IP, then compare that version and its protocols with the OSI reference model that we discussed earlier.

Once you understand the protocols and processes used at the various levels of the DoD model, we’ll take the next logical step by delving into the world of IP addressing and the different classes of IP addresses used in networks today.

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Subnetting is so vital, it will be covered in its own chapter, Chapter 2, “Easy Subnetting.”

Because having a good grasp of the various IPv4 address types is critical to understanding IP addressing, subnetting, and variable length subnet masks (VLSMs), we’ll explore these key topics in detail, ending this chapter by discussing the various types of IPv4 addresses.

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

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Introducing TCP/IP

TCP/IP is at the very core of all things networking, so I really want to ensure that you have a comprehensive and functional command of it. I’ll start by giving you the whole TCP/IP backstory, including its inception, and then move on to describe the important technical goals as defined by its original architects. And of course I’ll include how TCP/IP compares to the theoretical OSI model.

A Brief History of TCP/IP

TCP first came on the scene way back in 1973, and in 1978, it was divided into two distinct protocols: TCP and IP. Later, in 1983, TCP/IP replaced the Network Control Protocol (NCP) and was authorized as the official means of data transport for anything connecting to ARPAnet, the Internet’s ancestor. The DoD’s Advanced Research Projects Agency (ARPA) created this ancient network way back in 1957 in a cold war reaction to the Soviet’s launching of Sputnik. Also in 1983, ARPA was redubbed DARPA and divided into ARPAnet and MILNET until both were finally dissolved in 1990.

It may be counterintuitive, but most of the development work on TCP/IP happened at UC Berkeley in Northern California, where a group of scientists were simultaneously working on the Berkeley version of UNIX, which soon became known as the Berkeley Software Distribution (BSD) series of UNIX versions. Of course, because TCP/IP worked so well, it was packaged into subsequent releases of BSD Unix and offered to other universities and institutions if they bought the distribution tape. So basically, BSD Unix bundled with TCP/IP began as shareware in the world of academia. As a result, it became the foundation for the tremendous success and unprecedented growth of today’s Internet as well as smaller, private and corporate intranets.

As usual, what started as a small group of TCP/IP aficionados evolved, and as it did, the US government created a program to test any new published standards and make sure they passed certain criteria. This was to protect TCP/IP’s integrity and to ensure that no developer changed anything too dramatically or added any proprietary features. It’s this very quality—this open-systems approach to the TCP/IP family of protocols—that sealed its popularity because this quality guarantees a solid connection between myriad hardware and software platforms with no strings attached.

TCP/IP and the DoD Model

The DoD model is basically a condensed version of the OSI model that comprises four instead of seven layers:

• Process/Application layer
• Host-to-Host layer or Transport layer
• Internet layer
• Network Access layer or Link layer

Figure 1.1 offers a comparison of the DoD model and the OSI reference model. As you can see, the two are similar in concept, but each has a different number of layers with different names. Cisco may at times use different names for the same layer, such as both “Host-to-Host” and Transport” at the layer above the Internet layer, as well as “Network Access” and “Link” used to describe the bottom layer.

Figure 1.1 The DoD and OSI models

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When the different protocols in the IP s...