Chapter Summary

This chapter provides an overview of the functions and purposes of computer networks. Key among the functions of the network are increased communication, both in real-time and via email, sharing of hardware between multiple users, reduction in overall cost and support of multiple devices, and the ability to share files.

Two network models are identified in this chapter: peer-to-peer networking and client/server networking. Peer-to-peer networking is restricted to networks with few users and does not use a centralized server. Peer-to-peer networks are most commonly seen in home network environments and in small offices.

The client/server model is more common and familiar than the peer-to-peer model, especially in larger networks. The client/server model uses a dedicated server and offers many advantages over the peer-to-peer network model. Perhaps most notable of these advantages is the ability to centrally manage the network, although the cost and administration requirements are higher than those of peer-to-peer networks.

Networks have both physical and logical topologies. The physical topology refers to the way the network is physically laid out, including media, computers, and other networking devices such as hubs or MSAUs. The logical topology refers to how data is transmitted around the network. Common network topologies include star, ring, bus, and mesh. Each of these topologies offers distinct advantages and disadvantages and various levels of fault tolerance.

Access methods are the methods by which data is sent onto the network. Two of the most common access methods are CSMA/CD, which uses a collision detection and contention method, and token passing.

The IEEE defines several LAN standards, including 802.2 (the LLC layer), 802.3 (Ethernet), 802.5 (Token Ring), and 802.11b (wireless). Each of these standards identifies specific characteristics, including the network's media, speed, access method, and topology.