The components in a LAN, computers (work and server nodes), NIC (Network Interface Cards) (computer/media communication), cabling (media), hubs (topology configuration), switches (data handlers), and routers (communication connectors) are readily available as off-the-shelf items. Their cost has dropped to a level that anyone can afford to buy them. Once installed, work in the seamlessly in the background without interference to users at any of the work nodes.

The one remaining ingredient is the network OS (Operating System) to handle the data that is generated on the network. All of the current OSs, UNIX, LINUX, Windows, Novell NetWare, and Mac OS, are network ready, meaning that the OS is capable of communicating with the OS on other machines that are suitably connected via the network components. The OSs contain the necessary protocols that allow communication through the network.

Computer networks provide one overall function. That function is to communicate in some manner with other computers that are connected together via some medium. The communication between these computers allows users to share data and resources. Data files created on one computer in the network can be shared with other computers. These data files can be anything that is digitally created, i.e., documents, spreadsheets, graphics, drawings, photos, databases, forms, or programs. Resource sharing concerns the physical and virtual devices that help users store, print, copy, send and receive the data. Shared resources greatly multiple the use of devices such as printers. Network shared printers can receive and print data from any computer (node) on the network. This is a cost savings in that each computer does not need a printer. Other shared resources include HDD (Hard Disk Drives). A large HDD on a server can be used by all the nodes connected to it for storage. Other shared resource devices include modems and fax machines. Shared resources can also be virtual. Application programs can reside on a server machine and be available to all users on the network. Databases can reside on a database server which is made available to multiple users. Virtual storage capacity can be made available to all users. Resource sharing usually results in a cost savings to the network owner.

Networks ease the cost of communicating with the outside world also. Having multiple computers at home or in an office connected in a network makes it easy to share the outside connection to the Internet or to another location. The network removes the necessity for dedicated POTS (Plain Old Telephone Service) lines to each machine. This is especially true with one of the digital (broadband) communication services. Adding a router or switch to a network allows one to share the communication connection between all the computers on the network. This is a real cost saving for the home or small office user.

There are two primary topology techniques used today in the layout of networks. They are token ring and Ethernet. Topology refers to the way the computers in the network are connected together. Ethernet has almost become the standard for SOHO. Most Ethernet networks follow the IEEE 802.3 standard. Ethernet data rates operate at 10BaseT (10 Mbps) and/or 100BaseT (100 Mbps). 10/100 Mbps hubs, switches, and routers are sold as off-the-shelf components and are well within the cost range of home or small office use. The Ethernet topology uses a star configuration with hubs and/or switches as the central data transmission point. In the star configuration, each computer node is connected via the cable to the hub or switch, which acts as the data transfer agent. Ethernet networks can be peer-to-peer or client-server based. Peer-to-peer networks consist of workstation computers, each of which must keep track of all the other computers in the network. In this configuration, all the computers are equal as to capability and can share resources such as printing and file storage. Most home networks are peer-to-peer configured.

In the client/server configuration, certain of the machines act as servers, providing resources to the other machines, which are the clients. Clients do the work and the server acts as the file and resource provider. Servers handle file storage, printing, communication, and application service among other functions. Servers usually have high performance CPUs, large RAM memory and HDD storage capacity. This configuration lends itself to the office environment, where several users may work on the same data files. The data is stored on the server, making it available to all who have need to use the data. Client/Server configurations have additional benefits in that the data is centrally located on one machine and can be secured and backed up easily.

How Does It Go Together?
Putting the components together comprises two distinct areas. One area is the hardware that physically makes the network and the second area is the software that makes the hardware function properly. The first hardware component is the computer. It must have a component that is the interface between it and the other computers. This is the network adapter or NIC, which is a communication device capable of handling the NOS calls for transmission through the cabling or media. The next component is the media or cable. This is the transmission line between the computers. The most common cable is UTP Cat 5 (Unshielded Twisted Pair CATegory 5) communication cable. This cable consists of four twisted pairs of wire that is arranged according to the IEEE 802.3 specification and carries the network signal from one computer to another. The cable and NICs usually are terminated with RJ 45 connectors and receptors. The third component is the hub or switch, which completes the star topology configuration of the network. If the network is a peer-to-peer configuration, then this is all of the hardware that is needed.

The hardware for the client/server configuration is essentially the same as the peer-to-peer, with the server being one more node on the network.

The second area concerns the software that makes everything work properly. Just as every computer must have an operating system – the set of computer instructions that manage its hardware and software applications – the LAN also requires a NOS (Network Operating System). The NOS manages all the data communication between the computers on the network. A key part of the NOS is the protocol that is used by each computer to communicate with others. The protocol is a very specific set of commands that guide the data through the computer levels from one node to another. The protocol standard that is being used today is the Internet protocol, TCP/IP. All of the current major NOSs have TCP/IP as either the major or one that can be selected.

The Microsoft Windows OS including Windows for Workgroups, Windows 95/98/ME, Windows NT/2000 are all network ready. Setup is required to make sure the computer talks to the NIC so that each computer can communicate with others in the network. Other NOS programs include UNIX, LINUX, Mac OS, Novell, and IBM OS/2. In fact, using the TCP/IP protocol stack, it is possible for each of these NOSs to communicate with the other over the Internet. And, the TCP/IP protocol is the standard of the Internet, making it easy to connect to the rest of the world from your network.

Networks that use Microsoft NT/2000 and Novell usually do so with servers added into the network mix. These NOSs are more sophisticated, providing for data manipulation and security, both within the network and outside it. The server handles the sophisticated features to make use of the network easier on users. The server waits for requests from the client computers to perform the functions requested. These are usually file storage and sharing, network printing control, or communications.

What Do The Routers Do?
Routers and other proxy servers are placed in the network mix to facilitate communication with the outside world. With the addition of bandwidth from the broadband providers such as cable company direct cable and telco DSL (Direct Subscriber Line), it becomes possible for individuals and small office users to simultaneously have two or more computers be on line at the same time. Routers are devices that determines the next network point to which a data packet should be forwarded toward its final destination. In the world of TCP/IP, the router can maintain its IP connection with the service provider while allowing more than one computer use the available bandwidth available from the service provider. Routers are usually located at the juncture of networks. In the case of a SOHO network, this juncture is at the SOHO network and the service provider network. This is a gateway to the Internet. Routers create and maintain tables of available transmission routes, their condition, and uses this information to determine the best route for a given data packet.

Today’s broadband routers incorporate technologies that move all network-to-Internet traffic through a single IP address. One of the technologies is IP NAT (Network Address Translation), which allows the IP addresses inside the router to all be sent and received through one external IP address. This is a security technique as well as the internal IP addressing scheme can be set as a non Internet transmitting address to the Internet. The only address seen from the outside is the one given or assigned to the external router port. The second technique that routers incorporate is DHCP (Dymanic Host Configuration Protocol), which provides each of the network nodes on the internal network to be assigned IP addresses from a single source. This makes setup of individual nodes easy to maintain. The major NOSs accepts DHCP for setup of IP addresses on nodes within the network. These IP addresses are usually set in the non-transmittable IP addressing scheme such as 192.168.1.1.

Switches are smart hubs and understand the network addressing scheme to send network traffic directly from point to point. Switches are much faster than hubs.

Conclusion
By now, it can be seen that the hardware side of network is no big deal. The components can be purchased off the shelf. The NIC drivers are easier to setup than in the past. Most of the operating systems from Microsoft, Novell, UNIX, LINUX, and Apple are network ready. Cabling has become easy to do as UTP Cat 5 RJ45 for Ethernet has become the off the shelf standard for SOHO.

There are advantages to networking more than one computer to leverage the use of resources. The number of printers, etc., can be reduced in a network through sharing. Data can be used by more than one user easily. Internet connections, especially broadband, can be shared by more than one computer, which is an advantage over the analog POTS modems.