This chapter provides an overview of several network concepts. The topics of this chapter are:
A network can be defined as two or more connected computers that share data or other resources.
Networking can also be defined as:
Some example of kinds of networks are given in the text.
Networks originated with mainframes, which were typically used from terminals that had no computing power of their own. This kind of computing follows the centralized model. All computing is actually done at a central location (the mainframe) not at the terminals. There are several problems with this model: all processing is done at one place, increasing the computing power of the network is expensive, and the programs that run on these networks tend to be expensive custom made programs.
Some critical terms appear in the chapter:
If entities on a network act as peers, then this is Peer-to-Peer Networking. If entities act in strictly defined roles, as either servers or clients, but not as peers, then this is Server-Centric Networking. Most PC networks are this type. A third term, Enterprise Network, is used to describe a network with some characteristics of each of the other two types.
Most new networks follow a client/server model, which is also a distributed computing model. Clients typically perform some or most of the processing on the network, while servers provide services like data storage, instead of providing all the computing power. Client/server networks are typically easier to upgrade, both on the client side and on the server side.
The text mentions two other phrases, used to describe other computing models. Two-tier computing describes a client at the first tier that only formats information for display, and a server at the second tier that performs processing and data storage. Three-tier computing adds a tier in between the client and the server. The new second tier computer accepts a request from the first tier, and turns it into a request that the third tier computer can understand.
The word workstation is used to describe a computer that acts as a client in a client/server network. It may be a computer with a lot of processing power, which increases the ability of users on such a network to work faster and better.
A third kind of networking is referred to as both web-based networking and as collaborative computing. It is not explained in the text. Collaborative computing can only be done by networking. In this scenario, two or more computers share processing tasks, which they cannot do unless they are in a network. An example is the use of multiple computers to analyze radiotelescope data for the Search for Extraterrestrial Intelligence. The software to do so is currently available from the University of California at Berkeley. A more recent example is the Grid.org Research Program, which uses multiple computers for medical research.
A Local Area Network (LAN) covers a small area, like a building or a campus. A Metropolitan Area Network (MAN) covers a city, linking computers at various locations. A Wide Area Network (WAN) covers an area larger than a MAN. This may be a network between cities or countries. A Virtual Local Area Network (VLAN) is a subset of a LAN. It will not be physically separate from the rest of the LAN, but it will work as though is it a different LAN.
A Network Operating System is used to make a network possible, and to manage the network. Several network operating systems are listed, each of which can exist on a hybrid network:
The chapter lists several functions that servers can perfrom on a network. Some of the important ones are:
Topology is the study of shapes and configuration. Physical
topology is the way a network is wired (or wireless-ed?) together.
Networks configurations typically fall into one of several configurations:
The last topic in the chapter is the role of planning in network design. The idea here is that a good plan takes all the needs of the network into account before the network is built. A good design results from good planning. A bad design will result from lack of planning, and from lack of understanding of networking priciples.