Selecting the Network Type: Client/Server or Peer to Peer

In the next section, you'll have the opportunity to see how you can justify your decision to go with client/server or peer to peer.

As discussed, two important issues relating to choosing the type of network are scale and cost. A small office with little or no expansion will not need to deploy an expensive network server and run a Network Operating System (NOS) so that only a few users can share a few files and a printer. With this thought in mind, let's discuss client/server or server-based networking. We then take a look a peer-to-peer networking.

Client/Server Networking

Client/server networking entails two basic operations that are provided by a centralized server: authentication and support services. Workstations on the network don't require services from other workstations on the network. The service architecture of the network resides on one or more redundant, protected, regularly maintained, and backed up servers. These servers are dedicated to specific tasks: file services, Internet/wide area network (WAN) connectivity, remote access, authentication, backend distributed applications, and so forth.

In other words, workstations connected to a "pure" client/server network see only servers-they never see one another. A client/server network is a one-to-many scheme, with the server being the one and the workstations being the many. This architecture is the model used by large commercial websites, such as Amazon. The client is a small graphical front end that's delivered fresh from the server each time it's opened and a large server architecture at the back end that handles ordering, billing, and authentication. No user of Amazon knows another user is currently online-there's no interaction between users, just between the servers and the client system.

The client/server model is useful for large businesses that have to manage their computer users' computer resources efficiently. In a pure client/server environment, a great deal of the software that clients use at their workstations is stored on a server hard drive rather than on users' own hard drives. In this configuration, if a user's workstation fails, it is relatively easy to get the user back online quickly by simply replacing the computer on the desktop. When the user logs back in to the network, she'll have access to the applications needed to work.

The TCP/IP-based technology of the Internet has changed the accepted definition of client/server somewhat, with the focus being on distributed applications, where a "thin" client (such as a web page application running in a browser) works in tandem with a much larger server. The advantages of this model stem from the application's capability to run in a browser. Because browsers are universal-that is, they can run on Windows machines, Macs, UNIX boxes, and other systems-applications can be distributed quickly and effectively. Only the copy at the server needs to be changed for a web-enabled application, because the changes will be distributed when users open the new page.

A client/server architecture is appropriate if one or more of the following conditions apply to your situation:

• Your network user population is large, perhaps more than 20 computers. On a larger network, it might not be wise to leave resources entirely decentralized as you would on a peer-to-peer network, simply because there's no way to control the data and software on the machines. However, the size of the company's user base shouldn't be the only criteria. Indeed, size might be irrelevant, if the users are working on independent projects with little or no data sharing.
• Your network requires robust security. Using secure firewalls, gateways, and secured servers ensures that access to network resources is controlled. However, and once again, installing a firewall in the router that connects your LAN to the Internet may be all you need for security. In this situation, your company doesn't need a dedicated security server. Even more, the individual workstations will be running their own security software and performing virus scans periodically.
• Your network requires that the company's data be free from the threat of accidental loss. This means taking data stored on a server and backing it up from a central location.