Section 1.4. Summary

1.4. Summary

This chapter established a conceptual foundation for realizing all upcoming chapters. First, we clearly identified and defined all basic key terms in networking. We showed a big-picture view of computer networks in which from one side, connecting mainframe servers can be connected to a network backbone, and from the other side, home communication devices are connected to a backbone network over long-distance telephone lines. We illustrated how an Internet service provider (ISP) controls the functionality of networks. ISPs have become increasingly involved in supporting packet-switched networking services for carrying all sorts of data, not just voice, and the cable TV industry.

The transfer of data in packet-switched networks is organized as a multilevel hierarchy, with digital messages fragmented into units of formatted messages, or packets. In some circumstances, such as local area networks, packets must be modified further, forming a smaller or larger packet known as a frame. Two types of packet-switched networks are networks using connectionless protocol, in which no particular advanced connection is required, and networks using connection-oriented protocol, in which an advance dedication of a path is required.

A packet size can be optimized. Using the percentage of link utilization used by data, _d , as a main variable, we showed that the optimized packet size and the optimized packet delay depend on _d . The total delay of packet transfer in connectionless networks is significantly smaller than for connection-oriented networks, owing mainly to inclusion of signaling components in connection-oriented networks.

The next two chapters present an overview of the software and hardware foundations of our networking infrastructure. Chapter 2 provides some detail about communication protocols, and Chapter 3 introduces the devices used to construct a computer network.