|
Items in cart [0] |
Questions? Call 888-624-8373 |
PAPERBACK + PDF PAPERBACK PDF BOOK PDF CHAPTERS Free Resources |
||||||||||||||||
|
||||||||||||||||
|
|
|||||||||||||||
| ||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 29
Infroduclion and ConI~x!
WHAT IS THE INTERNET?
The Internet is a diverse set of independent networks, interlinked to
provide its users with the appearance of a single, uniform network. Two
factors shield the user from the complex realities that lie behind the illu-
sion of seamlessness: the use of a standard set of protocols to communi-
cate across networks and the efforts of the companies and organizations
that operate the Internet's different networks to keep its elements inter-
connected.
The networks that compose the Internet share a common architecture
(how the components of the networks interrelate) and software protocols
(standards governing the interchange of data) that enable communication
within and among the constituent networks.] The nature of these two
abstract elements architecture and protocols is driven by the set of
fundamental design principles adopted by the early builders of the
Internet. Because an appreciation of these principles is important to un-
derstanding what makes the Internet what it is, several of them are dis-
cussed at length below. Those who design and operate the Internet gen-
erally characterize the Internet in terms of these principles, which is not
surprising given that the Internet derives from work done by researchers
.
1Some would argue that the term "Internet" embraces the entire interconnected data
world rather than just the IP-based infrastructure. That broader definition includes net-
works using other protocols that interface with the IP-based Internet.
29
OCR for page 30
30
THE INTERNET'S COMING OF AGE
in computer science and engineering fields that rely on abstraction as a
technique for managing the complexity of what computer scientists study
or build.
The success of the abstracted interface through which users encoun-
ter the Internet contributes to the Internet illusion. Software such as Web
browsers makes use of names for things attached to the Internet-
www.example.com, for instance that hide the nature of the networks to
which both they and the user are connected. This, of course, has enor-
mous advantages for users, who need not worry about the complexities of
the networks they are making use of. Making things appear simple,
however, can lead to unmet expectations. For example, a user who at-
tempts but repeatedly fails to connect to a Web site say, www.example.
com will look to the Internet service provider (ISP) to resolve the prob-
lem. However, the odds are good that the computer named
www.example.com will turn out not to be attached to the network of the
user's provider. The provider, in fact, may not have a direct connection to
the provider servicing www.example.com and may not be able to even
tell the user what the problem is, where the problem is located, and the
likelihood of its happening again. If a user considers connecting to that
site to be mission-critical, such a response is likely to be very frustrating.
Advances in technology and services can, however, improve the quality
of the illusion substantially, as can a better understanding by users of
how the Internet is constructed. We will return to the technological,
economic, and policy issues surrounding interconnection in Chapter 3.
One consequence of the Internet illusion is that the ordinary Internet
user is likely to assume that a connection to the Internet via a given
provider of Internet services amounts to a direct connection to the totality
of the Internet. But in reality, the user has only contracted for Internet
service with one of a number of ISPs enterprises that provide Internet
connectivity to end users or other ISPs. Each ISP controls and operates
only a fraction of the global network system. To reach all of the end
destinations, content, or services that a user wishes to reach, an Internet
service provider may have to forward the user's communication through
several other networks, none of which it controls. Interconnections are
made largely though network links that are bilaterally coordinated be-
tween ISPs.
It is important to distinguish between the publics Internet, which is
2"Public" is used here in the same sense it has in the context of the public telephone
network. It does not denote public ownership; it denotes instead a network to which
anyone can connect and in which any customer can exchange traffic with any other. The
line between private and public is not always sharp; in particular, the physical networks
they use are not necessarily distinct.
OCR for page 31
INTRODUCTION AND CONTEXT
31
normally what is meant when "Internet" is written with a capital I, and
the Internet's core technologies (standard protocols and routers), which
are frequently called "IP technology" in reference to the key protocol
used on the Internet. Throughout this report, these terms Internet and
IP will be used in this way. The public Internet is distinguished by
global addressability (any device connected to the Internet can be given
an address and each address will be unique) and routing (any device can
communicate with any other). In practice, however, as a consequence of
interventions imposed by ISPs and local network managers such as the
deployment of firewalls and other technologies for filtering communica-
tions traffic not all data are allowed to pass to all devices and not all
devices are assigned public addresses. IP technologies are also employed
in private networks that have full, limited, or even no connectivity to the
public Internet; the distinction between public and private blurs because
to the extent that private networks acquire connections to the Internet,
they by definition become part of it.
If one looks at the elements that physically make up the Internet, one
sees two categories of objects. The networks that make up the Internet are
composed of communications links, which carry data from one point to
another, and routers, which direct the communications flow between links
and, ultimately, from senders to receivers. Communications links may
use different kinds of media, from telephone lines to cables originally
deployed for use in cable television systems to satellite and other wireless
circuits. Internal to networks, especially larger networks in more devel-
oped parts of the world, are links that can carry relatively large amounts
of traffic, typically via optical fiber cables. The largest of these links are
commonly said to make up the Internet's "backbone," though this defini-
tion is not precise and even the backbone is not monolithic.3 Links closer
to users, especially homes and small businesses, typically have connec-
tions with considerably less capacity. Large organizations, on the other
hand, tend to have high-capacity links. Over time the effective capacity of
links within the network has been growing. Links to homes and small
businesses the so-called "last mile" have until recently, with the emer-
gence of cable modem, digital subscriber line (DSL), and other technolo-
gies, been largely constrained to the relatively low speeds obtainable us-
ing analog modems running over conventional phone lines. Analog
modems remain the dominant mode of home access.
3There is no easy way to specify which networks comprise the Internet backbone. For
instance, in some countries a rather modest link may serve as the local backbone. Nor do
all connections between providers take place through the backbone there is no assurance
that any particular data packet will flow through any part of the Internet backbone.
OCR for page 32
32
THE INTERNET'S COMING OF AGE
Routers are computer devices located throughout the Internet that
transfer information across the Internet from a source to a destination.
Routing software performs several functions. It determines the best rout-
ing paths, based on some set of criteria for what is best, and directs the
flow of groups of data (packets) through the network. Path determina-
tion at each step along the way depends on information that each router
has about the paths from its location to neighboring routers as well as to
the destination; routers communicate to one another some of this path
information. A number of routing algorithms that determine how routers
forward packets through the network are in use; routing protocols medi-
ate the interchange of path information needed to carry out these algo-
rithms.
The Internet can be divided into a center, made up of the communica-
tions links and routers operated by Internet service providers, and edges,
made up of the networks and equipment operated by Internet users. The
line between center and edge is not a sharp one. Users who connect via
dial-up modems attached to their computers clearly sit at the very edge.
In most business settings as well as in an increasing number of homes,
LANs sit between the ISP and the devices that the Internet connects.
These LANs, and the routers, switches, and firewalls contained within
them, sit near the edge, generally beyond the control of the ISP,4 but not at
the very edge of the network.
Software applications running on these computing devices today,
typically PCs use Internet protocols to establish and manage informa-
tion flows that support applications over the Internet. Much as a common
set of standard protocols lies at the core of the Internet, common stan-
dards and a common body of software are features of many applications,
the most common being those that make up the World Wide Web (the
Web). The Web adds its own protocols for information exchange that
build on top of the fundamental Internet protocols, and it also provides a
standard way of presenting information, be it text or graphics. More
specialized software, which also makes use of the Internet's basic proto-
cols and frequently is closely linked to Web software, supports such ap-
plications as real-time audio or video streaming, voice telephony, text
messaging, and a whole host of other applications. In light of the promi-
nence of the Web today, Web-based applications and the content and
services provided by them are sometimes viewed as synonymous with
the Internet; the Internet, however, is a more general-purpose network
over which the Web is layered.
4Though ISPs do sometimes provide firewalls for their customers.
OCR for page 33
INTRODUCTION AND CONTEXT
33
Following usage from the telecommunications industry, the essential
physical components communications links and routers of the
network (including links that are parts of other networks, such as the
telephone lines used by dial-up modems or DSL or the high-capacity
fiber-optic cables shared among Internet, other data, and voice communi-
cations services) can be referred to as "facilities." Internet service provid-
ers use these facilities to provide connectivity using the Internet proto-
cols. What is done with the facilities and basic connectivity comes under
the heading "services." These services, which include such things as
access to content (e.g., viewing Web sites, downloading documents, or
listening to audio), electronic commerce (e.g., shopping, banking, and bill
paying), or telephony, are enabled by both devices and software in the
hands of users and service providers. Some services are enabled merely
by installing software on user computers, while others rely on functional-
ity implemented in computers and software attached to the Internet by a
third party. In either case, the general-purpose nature of the Internet has
meant that there does not have be any arrangement between the Internet
service provider and the provider of a particular service. While this state-
ment generally holds true today, we are seeing the emergence of excep-
tions to it in the form of application-specific delivery networks (e.g.,
Akamai) that employ devices located throughout the network, generally
near the edges. Chapter 3 discusses these trends and their implications
for the future development of the Internet.
A multitude of businesses are based on selling various combinations
of these elements. For instance, many Internet service providers (ISPs)
integrate connectivity with content or services for their customers. Some
ISPs rely in part or in toto on access facilities (e.g., dial-up modem pools)
owned and operated by other providers, while others operate most or all
of these facilities themselves. Also, ISPs may opt to own and operate their
own communications links, such as fiber-optic cables, and networks or
they may run Internet services over links and networks owned and oper-
ated by other communications companies (just as companies have resold
conventional voice telephony services for years).
The tale is well told about how, over the past decade, the Internet
evolved from a novel, but still developing, technology into a central force
in society and commerce,5 and the committee will not belabor the point
here. Suffice it to say that the transformations resulting from the Internet
along with expectations for continued growth in its size, scope, and influ-
5see, for example, computer science and Telecommunications Board ~csTsy, National
Research Council. 1996. The Unpredictable Certainty: Information Infrastructure Through
2000. Washington, D.C.: National Academy Press.
OCR for page 34
34
THE INTERNET'S COMING OF AGE
ence, have given rise to widespread interest and concern on the part of
government and society. A more realistic and better-informed appraisal
of Internet issues has become imperative now that governments at all
levels seek to control its evolution and use and dedicated issue-advocacy
groups have begun to proliferate. This report, written by a group of
experts in a number of areas technologies, operation, and management
of the Internet; associated communications infrastructures, such as the
public switched telephone network; and related policy and social issues-
is intended to explain key trends in the Internet's evolution and their
implications for policy. It focuses on trends that are often misunderstood
or incompletely treated by the mass media and it highlights specific areas
of policy that warrant more or better consideration. The remainder of this
chapter characterizes the Internet's special design attributes and outlines
several key trends in facilities and services.
SUCCESS BY DESIGN-
ABSTRACT FEATURES AND PRINCIPLES
Why has the Internet been so successful? Much of the answer lies in
the combination of two factors functionality and lower costs. The new
functionality stems from the Internet's unique design principles and fea-
tures that make connection, interconnection, and innovation in both fa-
cilities and services relatively easy. The Internet's characteristics have
also made it possible to use the underlying communications infrastruc-
ture more efficiently, thereby setting a lower price point for the commu-
nications it enables. Both factors have generated a pattern of innovation
in Internet technologies and uses.
Its relatively rapid responsiveness to users and other design attributes
distinguish the Internet from other parts of the information infrastruc-
ture, such as the public switched telephone network (PSTN) or the televi-
sion networks (cable and broadcast). The design of those other networks
is more focused on the center, and greater functionality is located within
the networks. They have been more centrally developed and managed
and historically have limited what users can do with them. In contrast, as
detailed below, the Internet's design is effectively neutral to what services
operate across the network. This enables a relatively unrestricted set of
applications to run over it without the need for changes to be made within
the network.
Much of the design of the Internet can be traced to the principles
adopted by the research community that undertook its early develop-
ment. These principles and the resulting architecture have been codified
in research papers and in a special set of documents describing the
Internet's design known as requests for comments (RFCs), a name reflect-
OCR for page 35
OCR for page 36
OCR for page 37
OCR for page 38
OCR for page 39
OCR for page 42
OCR for page 43
OCR for page 44
OCR for page 45
OCR for page 46
OCR for page 47
OCR for page 48
OCR for page 49
OCR for page 50
OCR for page 51
OCR for page 52
Representative terms from entire chapter:
internet service
INTRODUCTION AND CONTEXT
35
ing the interactive and iterative nature of Internet technology develop-
ment. Especially notable are the articulation of the end-to-end arguments
and RFC 1958.7
These and other documents embody some value judgments and re-
flect the fundamental political and ethical beliefs of the scientists and
engineers who designed the Internet: the Internet architecture reflects
their desire for as much openness, sharing of computing and communica-
tions resources, and broad access and use as possible. For example, the
value placed on connectivity as its own reward favors gateways and in-
terconnections over restrictions on connectivity but the technology can
be used permissively or conservatively, and recent trends show both.
Another value underlying the design is a preference for simplicity over
complexity.
These values have been advanced through the architectural view
embodied in voluntary standards set by such bodies as the Internet Engi-
neering Task Force (IETF),8 which has been the dominant standards-
setting body. Within this body, there has been open competition between
compatible implementations. Other standards-setting bodies have also
contributed to the establishment of key standards. One such body is the
World Wide Web Consortium, which has worked on standards related to
the Web. Another is the International Telecommunication Union (ITU).
To date, Internet standards generally tend to be developed on a per-
ceived-need basis and respond to technological developments; they also
continue to be linked to the activities of the network research community.
The design values of the Internet have been reinforced by the envi-
ronment in which the Internet was developed. In its early years as a
cooperative research project, it was isolated from some of the stresses and
strains associated with commercial marketplace interactions. Today the
IETF, like other organizations associated with the Internet, must respond
to the economic forces of a robust marketplace. Whether and how the
traditional Internet design values will be maintained is an important issue
for the future of the Internet.
6See J.H. Saltzer, D.P. Reed, and D.D. Clark. 1984. "End-to-End Arguments in System
Design," ACM Transactions on Computer Systems 2~4~:277-288, November.
7Internet Architecture Board. 1996. Architectural Principles of the Internet, Brian Carpenter,
ea., Request for Comments (RFC) 1958, June. Available online at
36
THE INTERNET'S COMING OF AGE
The Internet's "Hourglass" Architecture
As an open data network,9 the Internet can operate over different
underlying technologies, including those yet to be introduced, and it can
support multiple and evolving applications and services. In this layered
architecture, bits are bits and the network does not favor by its design or
effectiveness any particular class of application.l° Evidence of this open-
ness lies in the fact that the Internet's essential design predated a number
of communications technologies (e.g., LANs, ATM, and frame relay) and
applications and services (e.g., e-mail, the World Wide Web, and Internet
radio) in use today and that within the Internet all of these technologies
and services, both new and old, can coexist and evolve. The shape of an
hourglass inspired its selection as a metaphor for the architecture the
minimal required elements appear at the narrowest point, and an ever-
increasing set of choices fills the wider top and bottom, underscoring how
little the Internet itself demands of its service providers and users.ll
As a consequence of this hourglass-shaped architectural design, inno-
vation takes place at the edge of the network, through software running
on devices connected to the network and using open interfaces. By con-
trast, the PSTN was designed for very unintelligent edge devices tele-
phones and functions by means of a sophisticated core that provides
what are termed "intelligent facilities." Edge-based innovation derives
from a fundamental design decision made very early in the development
of the Internet and embodied in what is called the end-to-end argument in
systems design.l2 Aimed at simplicity and flexibility, this argument says
that the network should provide a very basic level of service data trans-
port and that the intelligence the information processing needed to
provide applications should be located in or close to the devices at-
tached to the edge of the network.
Underlying the end-to-end argument is the idea that it is the system
9Computer Science and Telecommunications Board (CSTB), National Research Council.
1994. Realizing the Information Future: The Internet and Beyond. Washington, D.C.: National
Academy Press.
10The layering principle is a powerful one and appears in other contexts. One sees oper-
ating system application interfaces such as those provided by Windows or Unix that allow
a large number of application programs to run on diverse computing platforms as well as
bus protocols (e.g., PCI or USB) that allow a large number of peripheral devices to work
with a variety of different computing platforms.
1lSome caution is needed in interpreting the hourglass metaphor. The narrow "waist" at
the middle of the hourglass is a metaphor for the minimally specified choice of technology
at this point and is not intended to convey any sense of a choke point or bottleneck.
12This was first expressed in J.H. Saltzer, D.P. Reed, and D.D. Clark. 1984. "End-to-End
Arguments in System Design," ACM Transactions on Computer Systems 2~4~:277-288.
INTRODUCTION AND CONTEXT
37
or application, not the network itself, that is in the best position to imple-
ment appropriate protection. If the network or network provider tries to
take on this task it is likely to implement something that is too heavy-
handed and performance-inhibiting for some applications and too light
for others. Both the sender and receiver are held ultimately responsible
for assuring the reliability of communications services (e.g., making sure
that what is received is complete and in order), so as to protect end users
against the vagaries of the networks that lie between them.l3 End systems
are also responsible for protecting themselves an end system must be
able, for example, to authenticate the sender of a message requesting, say,
the deletion of a file located on the system.l4
The original architects of the Internet made a key design decision to
use the principle of layering to separate applications from the underlying
transport infrastructure of the Internet. By hiding the realities of how the
Internet is constructed for instance, the topology of the network or the
physical configuration of its elements, how routing is performed within
the network, or how particular data transport services are implemented-
the architecture enables people to write applications that run over it with-
out having to possess any knowledge of these realities. In fact, without
using specialized diagnostic tools, there is very little way for application
software that makes use of the Internet to discover the detailed character-
istics of the underlying networks. In general, even a poorly designed
application can be added in a few sites at the edge of the network without
putting the network at risk; this is how new applications can be experi-
mented with, tested, and improved.
This manifestation of the Internet illusion discussed above has been
key to the explosion of new services and software applications of the
Internet. The combination of a standardized interface to the network and
the location of intelligence at the edges means that developers can write
and field new devices or new software without any coordination with
network operators or users or any changes in the underlying transport
130ne counterexample is denial-of-service attacks at the network level (i.e., "storms" of
IF packets sent to a network or router), which can be argued to deserve remedy within the
network itself.
140ne can think of the result of combining the end-to-end argument and the hourglass
architecture in another way. By providing an unreliable datagram delivery service in which
the network attempts to deliver a given datagram (piece of information) but does not guar-
antee such delivery, the Internet makes minimal assumptions about the characteristics of
the underlying transmission networks and passes a minimal set of functions up to higher
levels of the protocol. This design allows complex networks of connectivity to be overlaid
across a highly diverse collection of communications elements.
38
THE INTERNET'S COMING OF AGE
network. Nor do new applications or changes need to be deployed all at
once. Even though many developers of network applications do not un-
derstand or appreciate the technical and management challenges con-
fronting those who build and operate Internet networks, they are still able
to succeed in developing all kinds of popular new applications.
Thus, not only do we see PCs and larger computer systems attached
to the Internet, we now see televisions (e.g., WebTV), telephones, per-
sonal digital assistants (PDAs), and other devices being attached as well;
the future is likely to see many other devices emerge (e.g., music appli-
ances directly connected to the Internet). Of course, not all such applica-
tions represent improvements (and many will fade away over time), but
the Internet supports rapid feedback and the evolution of new and im-
proved features and function, both of which are associated with the
Internet's culture of cumulative knowledge building.
The corollary to ease of innovation at the Internet's edges is that
innovation at the center of the network is difficult and can be very slow
because building new features into the network requires the coordinated
actions of many providers and users. The problem is exemplified by the
difficulties of deploying new network-level features such as enhanced
quality of service or IP multicast (both discussed further in Chapter 2~.
This is not to say that an increasing number of sophisticated things
are not being implemented inside the Internet to optimize the delivery of
various services. For example, algorithms for filtering and load balancing
are found in some routers because they provide benefits in terms of ser-
vice quality for certain traffic (perhaps at the cost of raw switching speed).
Web caching entails adding devices throughout the network to improve
network performance. Such caching is achieved by moderating or redi-
recting specific types of network traffic in ways that can avoid congestion
by making use of temporary local copies of frequently accessed informa-
tion. Also, businesses that are building applications that require a great
deal of network capacity or low-latency delivery of information require-
ments not met very well on today's Internet are coping by building their
own application-specific delivery networks, which employ devices lo-
cated throughout the edges of the network as a work-around. Installation
requires cooperation (and may require colocation) with particular ISPs.
These technologies are controversial from an architectural and robustness
standpoint as they disturb the end-to-end model. Robustness implica-
tions are discussed in Chapter 2 and architectural implications are dis-
cussed in Chapter 3.
INTRODUCTION AND CONTEXT
39
The Robustness Principle
1ne robustness principle is arguably the single most enabling char-
acteristic of the Internet.l6 It was initially adopted for the ARPANET in
order to accommodate the unpredictably changing topologies anticipated
for defense applications (i.e., dynamic network reconfiguration) and then
for the Internet in order to accommodate interconnecting a diverse set
networks built by multiple implementors out of components using mul-
tiple implementations (i.e., heterogeneity of devices and technologies).
In accommodating both requirements, the Internet accommodates decen-
tralized management, growth, and accordingly evolution.
In practice, this robustness principle has taken several forms. One
way of viewing robustness is that the rule for interpreting standards
(and other specifications) that are not quite as precise as they might be in
a perfect world should be for the sender to take the narrowest interpreta-
tion (i.e., the intersection of all possible interpretations) and for the re-
ceiver to be prepared for the broadest possible interpretation (i.e., the
union of all possible interpretations).l7 Robustness also entails conserva-
tive and careful design at the transport level that is able to deal with a
15The robustness being discussed here should not be confused with the same term used
elsewhere in this report, especially Chapter 2, where it denotes lack of vulnerability to
failures or attack.
16This principle was written down by Jon Postel in the 1979 Internet protocol specifica-
tion: "In general, an implementation must be conservative in its sending behavior, and
liberal in its receiving behavior" don Postel. August 1979. Internet Experiment Note (IEN)
111 (the IP specification), p. 22~. The same text appears in September 1981, in RFC 791,
p. 23, and a variant appears in the TCP specification, under the heading "robustness prin-
ciple": "TCP implementations should follow a general principle of robustness: be conser-
vative in what you do, be liberal in what you accept from others" (Information Sciences
Institute, University of Southern California. 1980. DOD Standard Transmission Protocol, RFC
761, January. Available online at ~. A conservative
approach in Internet protocol design appeared earlier in Internet Engineering Note 12.
However, that paper falls short of enunciating a "robustness principle." See Lawrence L.
Garlick, Raphael Rom, and Jonathan B. Postel. 1977. Issues in Reliable Host-to-Host Proto-
cols. Internet Engineering Note (IEN) 12. Augmentation Research Center, Stanford Re-
search Institute, Menlo Park, Calif., June 8. Available online from
42
THE INTERNET'S COMING OF AGE
about monthly charges. The level of charge may vary according to pro-
vider promises of service quality. Other factors affecting price include the
ISP's dependence on advertising as a source of revenue, the bundling of
sales of equipment and Internet service (e.g., "free PC" deals), and the
bundling of Internet access with content and special services. Business
clients of ISPs follow a variety of pricing models, frequently based on
usage. Pricing for interconnection within the Internet itself that is, the
charges that ISPs pay to other ISPs also follows a variety of pricing
models, ranging from flat (traffic-insensitive) rates for interconnection to
barter arrangements with peers; these models are in flux. Notably, un-
like the PSTN, very few pricing models are based on either distance or the
exact volume of traffic carried. Interconnection prices are often privately
negotiated rather than based on fixed rates. Internet interconnection con-
trasts with the PSTN, where terms for interconnection and financial settle-
ment are well established and the subject of regulation.
· Low barriers to entryfor innovation. Consistent with the "Criteria for
an Open Data Network," the Internet is designed to be open from the
standpoint of users, service providers, and network providers, and as a
result it has been open to change in the associated industry base as well as
in the technologies they supply and use. A wide range of applications
and services, some leveraging the commonality of IP and others addition-
ally leveraging standards layered on top of IP, most notably the Web
interface, have flourished. As that industry base grows and matures,
questions arise about whether innovation will face other kinds of entry
barriers.
· Tippy markets. The Internet is the epitome of a network market. By
definition, participation in a large network market is more rewarding; the
larger the network, the larger the number of users. A small initial advan-
tage in market share, often associated with being first, can snowball into a
large advantage. These snowball effects are amplified on the Internet by
the ease and negligible cost of distributing software through the network,
which can promote much faster change than is typical for a product with
physical distribution on a scale of months or a couple of years rather
than several years or a decade. The desire to tip the market, seen in many
competitive markets, is epitomized by the struggle to build a leadership
position in streaming audio and video. This tippiness of the Internet
marketplace suggests a pattern of highly concentrated markets and mar-
ket leaders who greatly outdistance their competitors an outcome that
2)Computer Science and Telecommunications Board (CSTB), National Research Council.
1994. Realizing the Information Future: The Internet and Beyond. Washington, D.C.: National
Academy Press.
INTRODUCTION AND CONTEXT
43
would be at odds with the historic expectation of heterogeneity in tech-
nology implementation. Indications are, however, that these positions of
leadership are unstable. At least sometimes, a sufficient investment of
resources or other circumstances can allow newcomers to trump the in-
cumbents and tip the market in another direction.22 In recent years, for
example, Microsoft acquired much of the market for Web browsers, a
market that was once dominated by Netscape Communications. Whether
these patterns prove enduring and sustainable remains to be seen.
The Internet has been well served by an insistence that there is often
more than one "right" answer to a question. Its designers argue that no
single technology solves all the problems well, or even well enough, so
that no single technology should be considered as the sole solution. Thus,
when there is a common standard, there are frequently multiple indepen-
dent implementations of it. No single vendor has cornered the market in
good technology, and when one has gotten close to a monopolistic posi-
tion, the traditional Internet community has been critical of the situation
because of its potential for inhibiting continued innovation. It is not that
developing proprietary extensions or protocols to implement optional
features (which can generally coexist with standard protocols) is a prob-
lem per se. Rather, a monopolistic position would preclude the signifi-
cant benefits of having the essential elements of the infrastructure (hard-
ware or software) exist in multiple, independent implementations,
available from multiple vendors. Competition has served the Internet
well.
Internet Organizations
Several private, nonprofit organizations play critical roles with re-
spect to the Internet. These include the Internet's principal standards-
setting bodies: the Internet Engineering Task Force (IETF), the Internet
Architecture Board (IAB), and the Internet Engineering Steering Group
(IESG). Along with the ever-growing number of other organizations in-
volved in setting Internet standards, they are grappling with a growing
number and diversity of stakeholders and with the ever-larger commer-
cial stakes associated with the outcomes of their work. Another class of
organizations deals with operational issues: for example, the North
American Network Operators Group (NANOG) provides a forum for
troubleshooting and exchanging technical and operational information.
22For an overview of network economics, see Hal Varian and Carl Shapiro. 1998. Informa-
tion Rules: A Strategic Guide to the Network Economy. Boston, Mass.: Harvard Business School
Press.
44
THE INTERNET'S COMING OF AGE
Most visible recently has been ICANN, a newly formed body that has
assumed overall responsibility for managing the Internet's addresses and
names. Its work has received considerable attention and been the subject
of vigorous debate as address and name management become more con-
tentious and controversial activities. And, while the Internet Corporation
for Assigned Names and Numbers (ICANN) was not established to take
on the broader mission of Internet governance, it has not been able to
avoid some international governance questions in the course of its work,
leading observers to see its potential to play a larger role in the ambigu-
ous arena of Internet governance. Regional address registries have re-
sponsibility for managing the pool of addresses delegated to each region
of the world.
KEY TRENDS IN INTERNET DEVELOPMENT
The Internet has already gone through several iterations. New rout-
ing protocols have been deployed in bounded administrative domains,
for example, and replaced with other protocols as technology has ma-
tured. IP addresses at one time had to be given out in blocks of fixed size,
whereas today they are assigned in blocks defined by demonstrated needs.
What has worked over a period of some 25 years has been continual,
generally gradual change, characterized in most cases by continued inter-
operation between newer and older hardware and software. Sudden
revolutionary changes for instance, the sudden phasing out of one pro-
tocol in favor of another have not worked as well.23 For this reason, it is
unrealistic to believe that major infrastructure components, whether hard-
ware or software, can be changed without a significant period of coexist-
ence and interoperation. The history of the Internet argues for an expec-
tation of change from time to time and for design choices that at each step
include the ability to transition to the next step.
Advancing the Internet is about improvements in three areas: (1) the
nature and business of supplying network facilities; (2) Internet connec-
tivity; and (3) applications, content, and services. One of the things that is
special about the Internet is that its architecture allows an Internet busi-
ness to separate these three areas or to combine them in different ways.
23One notable "flag day" transition occurred in the ARPANET on January 1, 1983, when
all hosts had to simultaneously convert from NCP to TCP. The transition, which came at a
time when the Internet was far smaller, nonetheless required careful advance planning
(Barry M. Leiner et al. 1998. A Brief History of the Internet. Version 3.1, February 20.
Available online from ~.
INTRODUCTION AND CONTEXT
45
Growth in Backbone Capacity
The heart of the Internet grows through the interactions of ISPs and
major equipment manufacturers (principally router vendors and commu-
nications circuit suppliers). Increased capacity speed, performance, and
the accommodation of more users and more connections is the watch-
word. In terms of fundamental communications, ever-increasing exploi-
tation of optical fiber facilities has been the trend. Growth in Internet
traffic (by a factor of roughly 2 every year) has been outstripping growth
of computing speed (by the Moore's law factor of 2 every 18 months).24
To maintain this trend, equipment manufacturers are constantly chal-
lenged to improve the performance of communications equipment nearly
twice as fast as the PC and PC-component manufacturers improve PCs.
For staying on this curve, the equipment industry is highly dependent on
the help of innovations from both industry- and government-funded re-
search (the latter comes chiefly from the Defense Advanced Research
Projects Agency (DARPA) and the National Science Foundation (NSF)~.
It is generally believed that given current technology and some sus-
tained research support, equipment manufacturers should be able to con-
tinue to improve performance in the time frames required to keep on this
performance trajectory. In 2005, if current trends persist, the fastest link
will be roughly 2 terabits per second (Tbps), requiring routers that can
move data at 100 Tbps rates internally, and 5 years later, links will be
approaching the 100 Tbps level. At that point, routers that can handle
petabits (1000 Tb) per second will be required, and the requirement for
extremely fast routers becomes a major challenge. Some predict that all-
optical networking unlike the networks today, which combine optical
fiber with routers based on electronics will provide a solution. How-
ever, the channel switching speeds of today's optical technologies are far
slower than the speeds of today's routers, suggesting that optical
switching's importance may come from automating and speeding up the
management of aggregated traffic flows.25
24See Lawrence G. Roberts. 2000. "Beyond Moore's Law: Internet Growth Trends."
Computer 33~1~:117-120.
25One thing that appears crucial is further development of optical multiplexing. One
particular technique, known as wavelength division multiplexing (WDM), allows one to
pack a great deal of data into a single fiber by using multiple lasers operating at different
colors in parallel (it is much harder to use one laser to signal at very high bandwidths). One
approach will be the use of link management techniques, whereby routers aggregate traffic
to different destinations, so that traffic is placed onto a switched flow, bypassing intermedi-
ate routers. These large aggregates, not individual packets, would be switched optically.
To switch a packet, the existing router technology works well. In this approach, different
colors would be configured on a timescale of minutes to days to carry these aggregates
from source to destination routers, bypassing intermediate routers and switches.
46
THE INTERNET'S COMING OF AGE
Growth and Diversification of the ISP Market
The several thousand Internet service providers differ widely in size,
type of service they provide, and type of interconnection they have with
other service providers. As the market has grown in overall size, it has
evolved to comprise both very large players the tier 1 providers that
constitute the Internet's backbone and the large, consumer-oriented ISPs-
and many smaller players that focus on particular segments of the mar-
ket. Some serve particular markets (e.g., consumers or businesses) while
others provide such specialized services as hosting Web servers for other
companies. Peering, transit, and other interconnection arrangements-
which have both technical and economic dimensions have played a vi-
tal role in enabling the interlinking that defines the Internet, and several
issues related to these arrangements and their evolution are covered in
Chapter 3.
Upgrading the Local Access Infrastructure
Today most home users access the Internet through narrowband con-
nections made by modems using the public switched voice network. This
approach has led to fairly ubiquitous access services from multiple pro-
viders that offer very similar pricing and features. Such access achieves
relatively low data rates compared to what the telephone company's cop-
per loops can provide and does not provide the continuous connectivity
that Internet protocols were designed to take advantage of. The approach
required little investment in new access infrastructure and could make
use of the existing voice infrastructure fairly straightforwardly.
Now, however, dial-up access, with its low bandwidth and need to
complete a telephone connection each time access is desired, is increas-
ingly seen as limited, though it remains the least common denominator
for residential service today. At the same time, a range of new applica-
tions that require higher bandwidth and/or continuous connectivity are
being developed.
Broadband access enables services that, because they require high
capacity and limited delay, cannot be provided via dial-up access to the
Internet; it also makes many existing services much faster and more re-
sponsive. Broadband also enables multiple applications to be run, such as
simultaneous telephony and Web browsing. Software or music down-
loads that require minutes or hours over a dial-up connection take as little
as a few seconds via a broadband connection. Another benefit of broad-
band Internet connections is that, rather then requiring a phone call and
connection to be set up, they can be online all the time. This has two
significant implications. Routine monitoring tasks can easily occur con-
INTRODUCTION AND CONTEXT
47
sinuously (e.g., notifying users that they have new mail), and network
interactions can take place immediately (without waiting the minute or
two required to establish a dial-up connection), reducing the overhead
required to retrieve information or conduct a transaction. Looking up a
telephone number online, for example, instead of in a phone book, is a
viable option when one does not need to wait for an Internet connection
to be established; similarly, other activities become possible with better
connectivity. While these advantages are compelling, it remains easier at
this early stage of deployment to posit likely benefits than to quantify
with confidence actual consumer demand.
While the wireline and wireless telephone companies still dominate
the provision of voice services and broadcast entertainment still uses ra-
dio signals delivered over the airwaves or via cable, delivery of voice,
video, and other services over the Internet is emerging. As an increasing
number of users have broadband Internet connections, it is reasonable to
project that the use of various IP-based telephony services is likely to
increase substantially and that video applications will probably grow as
well. A number of services that compete with existing broadcasting and
entertainment businesses are emerging that are likely to increase in use,
including Internet delivery of music and Internet "radio" broadcasting.
Another emerging trend is the use of distributed, peer-to-peer applica-
tions (Napster and its offspring, particularly those that operate without
any centralized server facility) to exchange content among Internet users,
capabilities that harken back to the early days of the Internet, which was
designed to support peer-to-peer connectivity. These developments will
have several implications, including a change in the value consumers
place on Internet access (especially broadband service) and potential
stresses on the Internet itself.
As an increasing number of people become familiar with broadband
and its implications, the rate and patterns of broadband deployment as
well as the types of services being offered have become the subject of
public debate today, with congressional and multilevel regulatory scru-
tiny in the United States and political activity by organizations represent-
ing consumer and industry perspectives.
Deployment is a nontrivial undertaking; it will require billions of
dollars in investment to deploy broadband pervasively. Broadband tech-
nologies are being deployed at varying rates by a number of companies.
Cable companies are deploying two-way hybrid fiber/coax infrastruc-
tures capable of providing high-speed Internet services. Both incumbent
and competitive local exchange carriers are also investing in broadband
access, primarily through a family of DSL technologies, which leverage
existing copper wiring to provide high-speed Internet services. As with
cable, the solution of leveraging copper plant is generally considered an
48
THE INTERNET'S COMING OF AGE
interim step on the path to providing very high bandwidth connections to
the home using fiber-optic cable, although the time line for this is both
uncertain and likely to vary according to local circumstances.
Because two major facilities for broadband cable and the incumbent
local exchange carrier's copper loops are owned by incumbent players
in regulated industries and the third option today wireless depends in
part on spectrum allocation, deployment issues are tightly coupled to
both the interests of incumbents and the evolution of the regulatory re-
gimes that apply to these players. Thus, for example, cable's move into
Internet access and telephony have led to increasing political activity and
government scrutiny of the terms and conditions of its Internet service
offerings and associated competitive conduct.
The 1996 Telecommunications Act26 sought to promote competition
and consumer choice as key enablers of high-quality, affordable broad-
band local access to the Internet. Efforts to enhance consumer choice fall
into two general classes: facilities-based competition and unbundling of
network elements through regulation. Facilities-based competition is
competition among multiple access providers each of which operates its
own infrastructure. In such a regime, competition would exist, for ex-
ample, between the copper pair infrastructure owned by the local ex-
change carriers, the hybrid fiber/coax infrastructure being deployed by
cable operators, and wireless services. The premise of facilities-based
competition is that a multiplicity of facilities-based providers and their
heterogeneous business models will keep any one provider from domi-
nating and creating a bottleneck for innovation and control of content on
the Internet.
Another approach to ensuring consumer choice included in the 1996
act is to use regulation to unbundle the elements of the incumbent carrier's
networks, thereby enabling the entry of competitors. For example, in-
cumbent local exchange carriers are required to resell their copper lines to
subscribers the so-called "local loops" to other telecommunications
providers, allowing these entrants to offer competitive voice service or
other services such as DSL over these lines. More recently, there have
been calls for various forms of unbundling of the cable infrastructure, an
idea generally referred to as "open access" (Box 1.1~. The architecture of
the Internet fundamentally supports unbundling the issues that arise
with respect to unbundling include what particular approaches work tech-
nically in the context of particular access technologies, as well as a com-
plex set of economic and policy issues.
26Telecommunications Act of 1996, Public Law No. 104-104,110 Stat. 56 (1996~.
INTRODUCTION AND CONTEXT
49
Growing Role for Wireless Services
At the same time as cable and DSL technologies are starting to be
deployed, there have been considerable interest and investment in build-
ing competitive Internet access via high-speed wireless networks. One
can also expect the development and deployment of wireless services to
provide mobile access. Deployment has benefited from FCC efforts to
open up radio-frequency spectrum for such services, and it remains con-
tingent on the ability to make spectrum available and to resolve issues
related to the siting of transmission towers in local communities. Addi-
tionally, new satellite ventures are planning to deploy broadband com-
50
THE INTERNET'S COMING OF AGE
munications delivered from space; these will be a boon to sparsely popu-
lated areas where any sort of terrestrial infrastructure deployment is prob-
lematic.
In addition to providing access in competition with wired technolo-
gies or access where terrestrial infrastructure is not cost-effective, wireless
Internet can be expected to play a key role for a wide range of mobile
applications. There are many instances, such as when a user is in a car or
in a public space, where being connected through a wire is simply not a
practical option. IP connectivity in such situations could lead to all sorts
of new applications (and businesses), some of which have not yet been
thought of and which might turn out to be as popular as normal e-mail or
Web surfing itself. The popularity of the i-mode phone service provided
in lapan by DoCoMo shows the potential for rapid adoption of wireless
data services elsewhere.
Voice and Data Services
Many industry analysts predict that the rapid growth of data net-
works, particularly the Internet, will result in voice traffic increasingly
being carried using IP technology (voice over IP or IP telephony). While
the time frame for completing such a transition is unclear today, it is clear
that many service providers, equipment manufacturers, and customers
are moving in this direction. The public switched telephone network
(PSTN) is itself evolving to a more data-centric architecture, and the land-
scape of equipment suppliers is also rapidly changing. As use of these
services grows, they will have significant impacts on the traditional, regu-
lated voice service providers and may provoke calls for IP telephony to be
subject to regulation akin to that in place for circuit-switched voice ser-
vices. Chapter 4 examines these issues, as well as the more general ques-
tion of what happens when Internet-based services compete with other
communications industries.
Rise in the Use of Single-Purpose Devices
Today the majority of devices connected to the Internet are general-
purpose computers. Most users access the Internet through general-pur-
pose computers that are used for a multitude of tasks, and the servers
used by providers of content and services over the Internet are also gener-
ally based on general-purpose computing systems. However, single-pur-
pose devices offer several advantages for both uses. First, a carefully
designed, single-purpose device can often be made much less inexpen-
sively, with prices more in line with prices of other consumer electronics
devices than those of general-purpose computers. Second, single-pur-
pose devices are likely to have fewer failure modes and harmful interac-
INTRODUCTION AND CONTEXT
51
lions with other devices. Third, single-purpose devices lend themselves
to simpler interfaces and greater ease of use.27
For those providing content and applications over the Internet, pos-
sible single-purpose devices include network-attached file servers and
specialized audio or video servers. For end users, a single-purpose device
running a standard protocol can interact with any service that supports
that protocol (e.g., consumers wishing to listen to music could use simple
devices that stream audio or simple stand-alone music players that down-
load music).
Looking ahead, it is reasonable to project that networked systems will
include a diverse set of embedded systems in homes and commercial
settings, and computers used in other infrastructures, such as electric
power, will also be networked. International Data Corporation, for ex-
ample, has forecast that the number of devices connected to the Internet
will more than double every year for the foreseeable future and that non-
PC devices will account for nearly half of Internet devices shipped by
2002.28 Acknowledging the limitations of market research, it is nonethe-
less reasonable to plan for their widespread use.
Such a future can have several significant implications for the Internet
infrastructure. Widespread use will, for example, increase the draw on
the IP address space. The existence of large numbers of more specialized
devices aimed at narrower applications also may put pressure on the
Internet model of using a single, standard protocol (as illustrated by the
introduction of the Wireless Access Protocol as a solution for the mobile,
wireless space). Finally, because they could be used for passive monitor-
ing, deployment of a large number of smaller networked devices also
raises privacy concerns, including the question of informed consent.
FUTURE EVOLUTION AND SUCCESS
Reflecting its widespread deployment and adoption,29 substantial
commercial investment,30 and broad societal awareness, the Internet has
become a mainline piece of the communications infrastructure. Expan-
27Conversely, a proliferation of single-purpose devices, especially in the absence of stan-
dardized interfaces, could complicate the user's experience.
28International Data Corporation (IDC). 1999. Death of the PC-Centric Era (IDC Executive
Insights). Boston, Mass.: IDC. Available online at
52
THE INTERNET'S COMING OF AGE
sion into the foreseeable future appears inevitable, and new technologies
and new applications that leverage these technologies and new opportu-
nities will continue to emerge. The Internet's design principles and the
values that underlie these principles have been critical to the spectacular
success of the Internet. However, from today's vantage point of relative
maturity, there are questions that need to be asked about the underlying
structures that have brought us to this point the looseness of the
Internet's internal coordination mechanisms, of the process by which
Internet standards are developed, and of the interconnection arrange-
ments that tie it together and questions about the Internet's scalability
and reliability. Because of the prominence of the Internet, as well as its
potential for disruptive effects on both business and society, there are
pressures for government to act in these and many other areas related to
the Internet. Thus far, telecommunications regulators have been reluc-
tant to intervene. Government involvement with the operation of the
Internet has largely been limited to places where it was already involved,
such as transitioning the administration of the Domain Name System, or
places where Internet and more traditional telecommunications issues
overlap, such as within the PSTN local exchanges. On the other hand,
there have been both regulatory attention and legislative activity aimed at
consumer protection, such as protection of personal privacy and protec-
tion against junk e-mail or spam, as well as measures aimed at content
and conduct over the Internet (e.g., the Communications Decency Act
and gambling) and measures aimed at enhancing Internet-based applica-
tions, such as legislation governing digital signatures.
Underlying this hands-off approach has been the belief that the
Internet will continue to expand, mature, and evolve and that interven-
tion could threaten that success. Indeed, indications are that much of this
evolution can be expected to occur naturally, without recourse to reme-
dial action by government or other players. However, the technical and
policy challenges alluded to above raise questions about whether existing
mechanisms are up to the task of supporting increasing demands and
pressures and what the role of government should and should not be. In
addressing these questions, this report seeks to distinguish the issues that
will probably be self-resolving from those whose resolution will require
greater attention and/or new approaches.
at Austin (Anitesh Barua et al. 1999. Measuring the Internet Economy: An Exploratory Study,
Technical report. Austin, Tex.: Center for Research in Electronic Commerce, Graduate School
of Business, University of Texas. Available online at ), which
found that the revenue of companies in the Internet infrastructure business (ISPs, including
backbone providers, network hardware and software companies, manufacturers of com-
puters and servers, suppliers of security products, and manufacturers of optical fibers and
associated hardware) totaled nearly $115 billion annually in 1998.
