Investigating Your Network s Facilities

Investigating Your Network's Facilities

If you tour an average network, you can't help but discover that many different types of equipment and a variety of related software are in use. If you inventory all the components in a network, you can use that data to figure out what's attached to your network and what functions various devices perform on your network.

The infrastructure that makes networking possible is made up of the equipment that hooks computers into a network, the cables or other networking media that ferry information between computers, and the hardware and software used to create and control a network. You may also call the collection of connections, cables, interfaces, and other equipment glue because these elements bind computers into a working network.

The three phases of networking

Network software falls into one of three categories: host/terminal, client/server, and peer-to-peer. Each category reflects a certain type of networked communication.

• Host/terminal networks are based on an old-fashioned model for networking, even if they don't use old-fashioned stuff. In this network's original version, users access information using a device called a terminal , which consists of nothing more than a screen, a keyboard, and a network connection. All the software runs on a powerful computer called a host , which resides elsewhere on the network. The lowly terminal doesn't do anything more than provide a way for users to access remote data and applications (which is why such devices are also known as dumb terminals ). In more modern versions, PCs can act like terminals by using terminal emulation software , which the PC uses to access a host. The PC still provides some local smarts and access to local word-processing software, spreadsheets, and so on. In fact, Windows Server 2003 supports host/terminal capabilities through a facility called Terminal Server.

• A client/server network consists of a collection of smart machines. One or more of these machines acts as a server and has lots of storage space, a powerful processor, and networking software so it can handle requests for services from other machines. The other machines that interact with the server are called clients . Sometimes, client/server networks are also called server-based networks to emphasize the server's key role. Windows Server 2003 provides a foundation for the client/server network, which is the subject of this book. However, Novell NetWare and UNIX servers also play similar roles on modern networks.

• On a peer-to-peer network , any machine that can be a client can also act as a server. Unlike client/server networks, no special purpose machine acts as a server. On a peer-to-peer network, all machines are more or less alike in capability and in the services they offer. If you use the built-in networking included in Windows XP Professional, Windows 2000 Professional, Windows NT Workstation, or Windows 95, 98, SE, or Me, you're using this type of networking software.

 

Workstations for everyone!

One of networking's primary advantages is that a network takes what you do at your desk - and we bet you usually call it "work" - and lets you do what you do more efficiently by allowing you to interact with remote resources and data. This means you can access a file on a server as if it's part of your own disk drive, send a job to a printer elsewhere on the network as if it were hooked directly to your machine, and so on. Sharing resources remains the most highly touted benefit of networking because it connects your desktop computer to file stores, printers, applications, and information resources that would otherwise be inaccessible or too expensive to add to every desktop computer.

The terms network client, desktop computer , and workstation are all used more or less synonymously in the networking world. No matter what you call them, these machines are where users do the bulk of their work (and perhaps some play at odd moments).

REMEMBER 

A desktop is also the area of a computer that displays the program icons and the wallpaper.

One of the key goals that drives networking is to interconnect all the desktops in an organization, whether they run a DOS, Windows, UNIX, Linux, or Macintosh operating system, so that they can communicate and share resources. Some of the resources shared by workstations include large disk arrays, expensive color or laser printers, CD-ROM jukeboxes, and high-speed Internet connections (all of which would be too expensive to connect to every desktop machine).

On most networks, the ratio of desktop machines to users is pretty close to one-to-one. In other words, each user has access to a workstation attached to the network, even if that user is not the only person who works on that machine. Because workstations are where requests for services originate, such machines are known as network clients, or more simply, as clients .

When you call such a machine a workstation , you emphasize its capability to support an individual user more or less independently. When you call such a machine a client , you focus on its connection to the network. Whatever you call it, it's a machine that sits on your desk and is connected to a network.

A server is always at your service

Networking is about obtaining access to shared services. Because networks are useless unless you can do something with them, access to services is what networking is all about.

On modern networks, servers provide the capabilities necessary to obtain access to resources or to do things. For example, when you send a print job to a networked printer, you can assume that, somewhere in the background, a print server is handling the job. Likewise, when you request a file from a network drive, a file server is probably involved. When you poke around in the network directory - you guessed it! - a directory server is pulling the strings. For every service, some type of server handles and responds to requests. Sometimes, a single server provides many services; at other times, a server provides only a single service.

KEY CONCEPT 

Computers that provide services to clients are generically called servers . A server's job is to listen for requests from clients for whatever service or services it offers, and to satisfy any valid requests for its services. In fact, validating service requests is an important part of what servers do - you wouldn't want just anyone to be able to print the salaries for everyone in your company just because a user asks a print server to do so. You want that server to verify that Bob is allowed to access that file before you let him print it! Throughout this book, you find out more about such validations and other key aspects of what it takes for a server to provide services.

The common path of networking

A common pathway must exist between any computer that requests services and any computer whose job it is to satisfy such requests. Just as you need a highway to drive from one city to another, you need a pathway over which your computer can send and receive data. On a network, that's the job of the media that tie all the various pieces together.

Look around and observe the types of cables and connections used on your network. Get a sense of the structure of your network so you can tell which highways the users use - from the side roads that only the folks in the accounting or shipping department use to the main road that all users use.

When you observe how all the pieces fit together - workstations, servers, and media - you get a reasonably complete view of your network. Figure 1-1 depicts a simple network diagram that shows these purely physical elements of a network. Notice that clients (desktop machines) outnumber servers, and that media tie all the pieces together. Networking follows the law of supply and demand, so the more clients you have, the more (or bigger) servers you'll need - and the more work will get accomplished!

Figure 1-1: A typical network with clients, a server, and infrastructure (or network media).