Evolution of TCP/IP technology is i

Evolution of TCP/IP technology is intertwined with evolution of the global Internet
for several reasons. First, the Internet is the largest installed TCPhP internet, so many
problems related to scale arise in the Internet before they surface in other TCPIIP internets. Second, funding for TCP/IP research and engineering comes from companies and
government agencies that use the operational Internet, so they tend to fund projects that
impact the Internet. Third, because most researchers use the global Internet daily, they
have immediate motivation to solve problems that will improve service and extend
functionality.
With millions of users at tens of thousands of sites around the world depending on
the global Internet as part of their daily work environment, it might appear that the Internet is a completely stable production facility. We have passed the early stage of
development in which every user was also an expert, and entered a stage in which few
users understand the technology. Despite appearances, however, neither the Internet nor
the TCPhP protocol suite is static. Groups discover new ways to use the technology.
Researchers solve new networking problems, and engineers improve the underlying
mechanisms. In short, the technology continues to evolve.
The purpose of this chapter is to consider the ongoing evolutionary process and examine one of the most significant engineering efforts: a proposed revision of IP. When
the proposal is adopted by vendors, it will have a major impact on TCP/TP and the global Internet.
600 The Future Of TCP/IP (IF'v6) Chap. 33
33.2 Why Change?
The basic TCPKP technology has worked well for over two decades. Why should
it change? In a broad sense, the motivation revising the protocols arises from changes
in underlying technologies and uses.
New Computer And Communication Technologies. Computer and network
hardware continues to evolve. As new technologies emerge, they are incorporated into the Internet.
New Applications. As programmers invent new ways to use TCPAP, additional
protocol support is needed. For example, the emphasis on IP telephony has led
to investigations of protocols for real-time data delivery.
Increases In Size And Load. The global Internet has experienced many years of
sustained exponential growth, doubling in size every nine months or faster. In
1999, on the average, a new host appeared on the Internet every two seconds.
Traffic has also increased rapidly as animated graphics and video proliferate.
33.3 New Policies
As it expands into new countries, the Internet changes in a fundamental way: it
gains new administrative authorities. Changes in authority produce changes in adrninistrative policies, and mandate new mechanisms to enforce those policies. As we have
seen, both the architecture of the connected Internet and the protocols it uses are evolving away from a centralized core model. Evolution continues as more national backbone networks attach, producing increasingly complex policies regulating interaction.
When multiple corporations interconnect private TCP/IP internets, they face similar
problems as they try to define policies for interaction and then develop mechanisms to
enforce those policies. Thus, many of the research and engineering efforts surrounding
TCPnP continue to focus on finding ways to accommodate new administrative groups.
33.4 Motivation For Changing IPv4
Version 4 of the Internet Protocol (IPv4) provides the basic communication
mechanism of the TCPnP suite and the global Internet; it has remained almost unchanged since its inception in the late 1970st. The longevity of version 4 shows that
the design is flexible and powerful. Since the time IPv4 was designed, processor performance has increased over two orders of magnitude, typical memory sizes have increased by over a factor of 100, network bandwidth of the Internet backbone has risen
by a factor of 7000, LAN technologies have emerged, and the number of hosts on the
?Versions I through 3 were never formally assigned, and version number 5 was assigned to the ST protocol.
Sec. 33.4 Motivation For Changing 1-4 6 0 1
Internet has risen from a handful to over 56 million. Furthermore, because the changes
did not occur simultaneously, adapting to them has been a continual process.
Despite its sound design, IPv4 must be replaced soon. Chapter 10 describes the
main motivation for updating IP: the imminent address space limitations. When IP was
designed, a 32-bit address space was more than sufficient. Only a handful of organizations used a LAN; fewer had a corporate WAN. Now, however, most medium-sized
corporations have multiple LANs, and most large corporations have a corporate WAN.
Consequently, even with careful assignment and NAT technology, the current 32-bit IP
address space cannot accommodate projected growth of the global Internet beyond the
year 2020.
Although the need for a larger address space is the most immediate motivation,
other factors contributed to the new design. In particular, to make IP better suited to
real-time applications, thought was given to supporting systems that associate a datagram with a preassigned resource reservation. To make electronic commerce safer,
the next version of IP is designed to include support for security features such as authentication.