The Internet Today
The decommissioning of the NSFNET had to be done in specific stages to ensure continuous connectivity to institutions and government agencies that used to be connected to the regional networks. Today's Internet infrastructure is a move from a core network (NSFNET) to a more distributed architecture operated by commercial providers such as UUNET, Qwest, Sprint, and thousands of others, connected via major network exchange points, as well as direct network interconnections. Figure 14 illustrates the general form of the Internet today.
Figure 1-4. The General Structure of Today's Internet
Figure 1-4. The General Structure of Today's Internet
The contemporary backbone of the Internet is a collection of service providers that have connection points called POPs (points of presence) over multiple regions. Its collection of POPs and the infrastructure that interconnects them form a provider's network. Customers are connected to providers via access or hosting facilities in a service provider's POP. These customers can be service providers themselves. The prevalent service models employed by ISPs today are discussed in more detail in Chapter 2, "ISP Services and Characteristics."
Providers that have POPs throughout the U.S. are commonly referred to as national providers. Providers that cover specific regions, or regional providers, connect themselves to other providers at one or more points. To enable customers of one provider to reach customers connected to another provider, traffic is exchanged at public Network Access Points (NAPs) or via direct interconnections. The term ISP (Internet service provider) is commonly used to refer to anyone who provides Internet connectivity service, whether directly to the end user, or to other service providers. The term NSP (Network Service Provider) was traditionally used to refer to backbone network providers. However, NSP is now used much more loosely to refer to any service provider that has a presence at the NAPs and maintains a backbone network.
NSFNET Solicitations
NSF has supported data and research on networking needs since 1986. NSF also supported the goals of the High Performance Computing and Communications (HPCC) Program, which promoted leading-edge research and science programs. The National Research and Education Network (NREN) Program, which is a subdivision of the HPCC Program, called for gigabit-per-second (Gbps) networking for research and education to be in place by the mid-1990s. All these requirements, in addition to the April 1995 expiration deadline for the Cooperative Agreement for NSFNET Backbone Network Services, led NSF to solicit for NSFNET services.
As discussed, the first NSF solicitation, in 1987, led to the NSFNET backbone upgrade to T3 links by the end of 1993. In 1992, NSF wanted to develop a follow-up solicitation that would accommodate and promote the role of commercial service providers and that would lay down the structure of a new and more robust Internet model. At the same time, NSF would step back from the actual operation of the core network and focus on research aspects and initiatives. The final NSF solicitation (NSF 93-52) was issued in May 1993.
The final solicitation included four separate projects for which proposals were invited:
• Creating a set of NAPs where major providers interconnect their networks and exchange traffic.
• Implementing a Routing Arbiter (RA) project to facilitate the exchange of policies and addressing of multiple providers connected to the NAPs.
• Finding a provider of a high-speed Backbone Network Service (vBNS) for educational and government purposes.
• Transitioning existing and realigned networks to support interregional connectivity by connecting to NSPs that are connected to NAPs, or by directly connecting to NAPs themselves. Any NSP selected for this purpose must connect to at least three of the NAPs.
Each of these solicitations is covered as a major section in this chapter.
Continue reading here: What Is a NAP
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