Lesson 1

When you think about an infrastructure, you think about a framework or a foundation. After all, infra- means within and structure is a foundation. An infrastructure supports or holds something together. The Internet is similarly held together by an infrastructure, a basic framework of technologies. This module discusses the core components of the Internet infrastructure, methods for establishing Internet connections, and ways to troubleshoot connectivity problems.
By the end of this module, you will be able to:

1. Explain the OSI (Open System Interconnection) model
2. Describe the core components of the Internet infrastructure and how they relate to each other
3. Describe the uses of hardware and software network connection devices
4. Describe the various Internet bandwidth technologies
5. Describe the purposes, functions, and features of various types of servers
6. Troubleshoot problems with Internet connectivity using various diagnostic tools

In the next lesson, you will learn about the OSI network architecture model.

Every computer that is connected to the Internet is part of a network. For example, you may use a cable modem to connect to an (ISP) Internet Service Provider and at work, you may be part of a (LAN) local area network. Most likely you still connect to the Internet using an ISP that your company has a contract with. When you connect to your ISP, you become part of their network and the ISP may then connect to a larger network and become part of their network. Hence, the Internet is simply a network of networks.
Most large communication companies have their own dedicated backbones connecting various regions. In each region, the company has a (POP) Point of Presence, and this POP is a place for local users to access the network of the company through a dedicated line. What is interesting here is that there is no overall controlling network. Instead, there are several high-level networks connecting to each other through (NAPs )Network Access Points.