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Lesson 2 Making connections
Objective Describe backbones and Network Access Points.

Describe Backbones and Network Access Points

Connect one computer to another and you have a network.
The Internet is a giant network of networks linking computers from all over the world. There are many kinds of networks, each defined by its communication protocol. On the Internet, computers can communicate across different platforms using a standardized addressing scheme. To review the Internet and the services it offers, click this sidebar. The basic elements of Internet communication are:
  1. Internet Service Providers (ISPs)
  2. Regional networks
  3. Network Access Points (NAPs)
  4. Backbones

Making Internet Connections

The Internet is a giant computer network linking computers from all over the world. For some users, the Internet is an infrastructure to access public and private networks. For other users, it is the essential bridge for the Web and email. The Internet comprises four essential parts:
  1. computers,
  2. networks,
  3. software, and
  4. users.

Parts of the internet consisting of computers and LAN
Parts of the internet consisting of computers and LAN

The Internet supports a wide range of services that are available to users. The basic Internet services are:
  1. Electronic mail (email)
  2. World Wide Web (the Web)
  3. Mailing lists and newsgroups
  4. Chat
  5. File Transfer Protocol

Internet Service Provider

When you send a message over the Internet from your home, you contact your Internet Service Provider (using a dial-up modem or a cable modem). Your Internet Service Provider either sends your message directly to a Network Access Point, from where it is placed onto the Internet's backbone, or onto a shared line if the target site is relatively local. A Network Access Point (NAP) is like an airline hub, it's where regional ISP's connect to the Internet backbone. The lines between Network Access Points, called backbones, are super-fast. An Internet Service Provider, or ISP, is a company that has a connection to the Internet and provides Internet access to others (individuals, as well as companies), usually for a fee. Today there are thousands of ISPs throughout the world. Examples of ISPs in the U.S. are Netcom, AOL, and Earthlink.
Regional Networks: ISPs pay a fee to connect to a regional network, which in turn connects to a national commercial backbone. However, some larger ISPs connect directly to one of the commercial backbones. In the United States some major regional networks are BARRNet in California, NEARNET in Northeastern U.S., and CICnet in the Midwest.

Network Access Points (NAPs)

Regional networks are connected to Network Access Points, or NAPs. A NAP is a major interconnection point: the airline-like hub described earlier in this lesson. NAPs reduce network lengths, provide routing flexibility, and produce bandwidth savings. Many regional ISPs interconnect directly with each other using leased lines for regional connections that do not require access to a NAP. The connection between NAPs and between some regional networks (and major ISPs) and NAPs takes place over high-speed pathways, or superlinks, called backbones. The information traveling through backbones is managed by routers. Routers direct the information to the appropriate backbone according to its destination, thus ensuring that it gets to where it's supposed to go and is not lost on the way. Commercial backbone providers include PSINet, UUNet, ANS/AOL, and Sprint.
The following diagrams illustrates NAPs and backbones.
Network Access Points in the Internet Backbone
Network Access Points in the Internet Backbone
The Internet backbone refers to the core network infrastructure that provides high-speed connectivity and routes data between different parts of the internet. The internet backbone is made up of several components, including:
  1. Network Access Points (NAPs): NAPs are physical locations where different internet service providers (ISPs) connect their networks to exchange traffic. NAPs are typically located in major cities and are managed by neutral third-party organizations.
  2. Internet Exchange Points (IXPs): IXPs are similar to NAPs, but they are usually smaller and located in more regional areas. IXPs allow ISPs and other network operators to exchange traffic with each other directly, rather than routing traffic through other networks.
  3. Tier 1 Network Service Providers: Tier 1 ISPs are large network operators that provide high-speed connectivity and routing between different parts of the internet. Tier 1 ISPs are interconnected with each other and do not pay for access to other networks.
  4. Tier 2 and Tier 3 Network Service Providers: Tier 2 and Tier 3 ISPs are smaller network operators that provide connectivity and routing services to customers and other networks. These ISPs typically purchase connectivity from Tier 1 ISPs or other network operators to provide internet access to their customers.
  5. Internet Service Providers (ISPs): ISPs are companies that provide internet access to end-users, such as individuals and businesses. ISPs may connect to the internet backbone directly or through a higher-level network operator.

These components work together to create a network of interconnected networks that provide high-speed connectivity and routing between different parts of the internet. The internet backbone is essential for the functioning of the internet, as it provides the underlying infrastructure that enables data to be transmitted and accessed across the globe.

The Internet backbone is composed of high-bandwidth lines interconnected with fast, high-capacity routers. Backbones can span large geographic areas. The backbone lines, generally installed by national long-distance telephone carriers or by the government, employ the highest speed transmission paths.

What are the Physical Characteristics of Network Access Points?

Network Access Points (NAPs) are physical locations where different Internet Service Providers (ISPs) connect their networks to exchange traffic. The physical characteristics of NAPs may vary depending on their size, location, and purpose, but here are some common characteristics:
  1. Data Centers: NAPs are often located in data centers, which are specialized facilities that house the equipment and infrastructure needed to support network connectivity. Data centers provide a controlled environment for the servers, routers, switches, and other networking equipment that is used to manage and direct internet traffic.
  2. High-Speed Connectivity: NAPs are designed to provide high-speed connectivity and low-latency connections between different networks. This is achieved through the use of high-speed fiber-optic cables, which can transmit data at very high speeds, and through the use of advanced networking equipment such as routers, switches, and load balancers.
  3. Redundancy and Resilience: NAPs are designed with redundancy and resilience in mind to ensure high levels of uptime and reliability. This may include redundant power supplies, backup generators, redundant networking equipment, and multiple connections to different network providers.
  4. Security: NAPs are designed with security in mind to protect against unauthorized access and cyber threats. This may include physical security measures such as access controls, surveillance cameras, and security personnel, as well as cybersecurity measures such as firewalls, intrusion detection systems, and antivirus software.
  5. Scalability: NAPs are designed to be scalable, so that they can support increasing levels of internet traffic as demand grows. This may involve adding additional networking equipment or upgrading existing equipment to handle higher data volumes.

Overall, the physical characteristics of NAPs are designed to support high-speed connectivity, redundancy, resilience, security, and scalability to ensure that internet traffic can be routed and transmitted quickly and reliably between different networks.
Network access points, or NAPs, tie together various ISPs and the national telecommunications companies.
Usability Testing

The Physical Structure of the Internet

The Internet has a loose structure whose topology is mainly a consequence of perceived commercial need being satisfied by a network service. The result is a broadly hierarchical structure, however, with some operators concentrating on providing core networks, others concentrating on connecting private users, and still others providing transit between users and the core.
Figure 3-2 illustrates a possible configuration. The core networks (called national service providers [NSP] in the United States) compete with each other to carry Internet traffic. ISPs high capacity links between their routers, capable of operating at gigabits per second and more. NSPs connect with each other in two ways:
  1. Through independent "network access points" (NAP). These are commercial operations and provide high bandwidth switching between networks. They are generally confined to a small geographical area (i.e. single building) and consist of high-speed networks such as gigabit Ethernet that host routers belonging to the NSPs. NAPs are sometimes called metropolitan area exchanges (MAEs).
  2. Through private "peering" arrangements. These are direct connections between routers belonging to the NSPs.

Figure 3-2: High-level Internet structure
Figure 3-2: High-level Internet structure. The networks shown may have complex structure internally. Each is run by a separate administration and is an autonomous system in Internet terminology.

In the next lesson, URLs and their function as IP addresses will be discussed.

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