ABSTRACT
Computer networks include a myriad of different physical elements, performing different functions. From the point of view of routing, computer networks comprise three types of physical elements: end devices, switching equipment, and communication media. Switching equipment is usually differentiated based on the type of addressing information used to make forwarding decisions. The Internet uses IP addresses to identify, at a worldwide level, the reachable network interfaces. Moreover, the application processes running on hosts are identified through the type of transport protocol used in the communication between them and their port numbers. The Internet addressing architecture includes the DNS service for mapping host names and URLs to IP addresses. An important classification of IP addresses is according to the number of interfaces they identify when used as destination addresses: unicast addresses identify a single interface, multicast addresses identify a group of interfaces, and broadcast addresses identify all interfaces.
