TUGAS DATA LINK CONTROL PROTOKOL

Architecture, history, standards, and trends
Today, the Internet and World Wide Web (WWW) are familiar terms to
millions of people all over the world. Many people depend on applications
enabled by the Internet, such as electronic mail and Web access. In addition,
the increase in popularity of business applications places additional emphasis
on the Internet. The Transmission Control Protocol/Internet Protocol (TCP/IP)
protocol suite is the engine for the Internet and networks worldwide. Its
simplicity and power has lead to its becoming the single network protocol of
choice in the world today. In this chapter, we give an overview of the TCP/IP
protocol suite. We discuss how the Internet was formed, how it developed
and how it is likely to develop in the future.
1.1 TCP/IP architectural model
The TCP/IP protocol suite is so named for two of its most important protocols:
Transmission Control Protocol (TCP) and Internet Protocol (IP). A less used
name for it is the Internet Protocol Suite, which is the phrase used in official
Internet standards documents. We use the more common, shorter term,
TCP/IP, to refer to the entire protocol suite in this book.
1.1.1 Internetworking
The main design goal of TCP/IP was to build an interconnection of networks,
referred to as an internetwork, or internet, that provided universal
communication services over heterogeneous physical networks. The clear
benefit of such an internetwork is the enabling of communication between
hosts on different networks, perhaps separated by a large geographical area.
The words internetwork and internet is simply a contraction of the phrase
interconnected network. However, when written with a capital "I", the Internet
refers to the worldwide set of interconnected networks. Hence, the Internet is
an internet, but the reverse does not apply. The Internet is sometimes called
the connected Internet.
The Internet consists of the following groups of networks:
• Backbones: Large networks that exist primarily to interconnect other
networks. Currently the backbones are NSFNET in the US, EBONE in
Europe, and large commercial backbones.
• Regional networks connecting, for example, universities and colleges.
4 TCP/IP Tutorial and Technical Overview
• Commercial networks providing access to the backbones to subscribers,
and networks owned by commercial organizations for internal use that
also have connections to the Internet.
• Local networks, such as campus-wide university networks.
In most cases, networks are limited in size by the number of users that can
belong to the network, by the maximum geographical distance that the
network can span, or by the applicability of the network to certain
environments. For example, an Ethernet network is inherently limited in terms
of geographical size. Hence, the ability to interconnect a large number of
networks in some hierarchical and organized fashion enables the
communication of any two hosts belonging to this internetwork. Figure 1
shows two examples of internets. Each is comprised of two or more physical
networks.