Backbone Backbone Router Router Internet, Intranet, Extranet Figure 8.2 Network components Chapter 8 The Internet and IP Infrastructures set of telecommunications protocols-the IP family (see Figure 8.3). The term client is often used to refer to a computer on a network that takes advantage of the services offered by a server. It also refers to a user running the client side of a client/server application. The term server describes either a computer or a software- based process that provides services to network users or Web services to Internet users. Networks connect servers and clients, allowing them to share information and computing resources. Network equipment includes cable and wire, network adapt- ers, hubs, switches, and various other physical connectors. In order for a network to be connected to the Internet, the network must send and retrieve data by using TCP/IP and related protocols. Networks can also be connected to form their own internets: Site-to-site connections are known as intranets, internal networks that are generally composed of LANs interconnected by a wide area network (WAN) that uses IP; and connections between partnering organizations, using IP, are known as extranets. The Internet is a complex, highly redundant collection of more than 10,000 interconnected autonomous systems, composed of telecommunications circuits connected with internetworking equipment, including routers, bridges, and switches. The level of redundancy varies, depending on how the autonomous sys- tems are connected. In an environment consisting of several network segments with different protocols and architectures, the network needs a device that not only knows the address of each segment but also can determine the best path for send- Figure 8.3 An internetwork Internet Basics ing data and filtering broadcast traffic to the local segment. The Internet moves data by relaying traffic in packets from one computer network to another. If a par- ticular network or computer (i.e., router) is down or busy, the network is smar