PART 1
The Contemporary Internet

The complexity of routing problems and solutions is tied closely to the growth and evolution of the contemporary Internet. Thus, before delving into specifics about routing protocols, you will find it extremely useful to have some general perspective and background information. Such historical developments as the Route Arbiter project, Network Access Points, and Network Information Services, covered in Chapter 1, continue to have extremely practical implications for organizations that want to be connected to global networks. General and network topology issues associated with Internet service providers are introduced in Chapter 2. Concepts of addressing and Classless Interdomain Routing, which are needed to control the depletion of the IP address space, are covered in Chapter 3.

Chapter 1—Evolution of the Internet

Chapter 2—ISP Services and Characteristics

Chapter 3—Handling IP Address Depletion

This chapter covers the following key topics:

•  Origins of the Internet; the Internet Today
Very brief history of the early Internet, with emphasis on its implementors and users, and on how it has evolved in the last decade.

•  Network Access Points
Internet service providers must connect, directly or indirectly, with Network Access Points (NAPs); customers will need to know enough to evaluate how their providers connect to the NAPs.

•  Route Arbiter Project
Overview of concepts central to the rest of this book: Route servers and the Routing Arbiter Database. Route servers are architectural components of NAPs, Internet service providers, and other networks.

•  Regional Providers
Background on the current Internet layout with respect to regional connection service and goals.

•  Network Information Services
Description of information collected and offered by central and distributed Internet information services. Includes description of templates that customers and providers must fill out to get connected.

Chapter 1
Evolution of the Internet

The structure and makeup of the Internet has adapted as the needs of its community have changed. Today's Internet serves the largest and most diverse community of network users in the computing world. A brief chronology and summary of significant components are provided in this chapter to set the stage for understanding the challenges of interfacing the Internet and the steps to build scalable internetworks.

Origins of the Internet

The Internet started as an experiment in the late 1960s by the Advanced Research Projects Agency (ARPA, now called DARPA) of the U.S. Department of Defense. DARPA experimented with the connection of computer networks by giving grants to multiple universities and private companies to get them involved in the research.

In December 1969, the experimental network went online with the connection of a four-node network connected via 56 Kbps circuits. This new technology proved to be highly reliable and led to the creation of two similar military networks, MILNET in the U.S. and MINET in Europe. Thousands of hosts and users subsequently connected their private networks (universities and government) to the ARPANET, thus creating the initial "ARPA Internet." ARPANET had an Acceptable Use Policy (AUP), which prohibited the use of the Internet for commercial use. ARPANET was decommissioned in 1989.

By 1985, the ARPANET was heavily used and congested. In response, the National Science Foundation (NSF) initiated phase one development of the NSFNET. The NSFNET was composed of multiple regional networks and peer networks (such as the NASA Science Network) connected to a major backbone that constituted the core of the overall NSFNET.

In its earliest form, in 1986, the NSFNET created a three-tiered network architecture. The architecture connected campuses and research organizations to regional networks, which in turn connected to a main backbone linking six nationally funded super-computer centers. The original links were 56 Kbps.

The links were upgraded in 1988 to faster T1 (1.544 Mbps) links as a result of the NSFNET 1987 competitive solicitation for a faster network service, awarded to Merit Network, Inc. and its partners MCI, IBM, and the state of Michigan. The NSFNET T1 backbone connected a total of 13 sites that included Merit, BARRNET, MIDnet, Westnet, NorthWestNet, SESQUINET, SURANet, NCAR (National Center of Atmospheric Research), and five NSF supercomputer centers.

In 1990, Merit, IBM, and MCI started a new organization known as Advanced Network and Services (ANS). Merit Network's Internet engineering group provided a policy routing database and routing consultation and management services for the NSFNET, whereas ANS operated the backbone routers and a Network Operation Center (NOC).

By 1991, data traffic had increased tremendously, which necessitated upgrading the NSFNET's backbone network service to T3 (45 Mbps) links. Figure 1-1 illustrates the original NSFNET with respect to the location of its core and regional backbones.

Figure 1-1  NSFNET-based Internet environment.

As late as the early 1990s, the NSFNET was still reserved for research and educational applications, and government agency backbones were reserved for mission-oriented purposes. But new pressures were being felt by these and other emerging networks. Different agencies needed to interconnect with one another. Commerical and general-purpose interests were clamoring for network access, and Internet service providers (ISPs) were emerging to accommodate those interests, defining an entirely new industry in the process. Networks in places other than the U.S. had developed, along with interest in international connections. As the various new and existing entities pursued their goals, the complexity of connections and infrastructure grew.

Government agency networks interconnected at Federal Internet eXchange (FIX) points on both the east and west coasts. Commercial network organizations had formed the Commercial Internet eXchange (CIX) association, which built an interconnect point on the west coast. At the same time, ISPs around the world, particularly in Europe and Asia, had developed substantial infrastructures and connectivity. To begin sorting out the growing complexity, Sprint was appointed by NSFNET to be the International Connections Manager (ICM)—to provide connectivity between the backbone services in the U.S. and European and Asian networks. NSFNET was decommissioned in April 1995.