A network is a group of computers, printers, and other electronic devices that communicate back and forth using a set of rules. These devices can be connected by various types of cable, radio waves, or infrared light. Over mediums such as these, network users are able to exchange documents and data with each other, print to the same printers, and generally share any hardware or software that is connected to the network. Each computer, printer, or other peripheral device that is connected to the network is called anode. Networks can have tens, thousands, or even millions of nodes.
In order to work properly, networks must be built according to certain rules. Cabling, for example, has to be under a certain length and must be installed properly to ensure proper network performance. The set of rules that governs how a network is put together is called its topology. The most common topology in use today is called Ethernet, which consists of computers and peripherals cabled together in specific ways. Ethernet is relatively inexpensive, easy to set up and use, and can be very fast.
Ethernet has evolved through three standardized “phases.” Each of these evolutionary changes has dramatically improved network performance. These Ethernet networking systems are named according to how fast they can move information. Speed is expressed in megabits per second (or Mbps). A bit represents an “on” or “off” condition, and eight bits are used to represent a single character.
Standard Ethernet, or 10Base-T operates at 10 Mbps, which is sufficient for low-bandwidth applications such as email and transferring small files across the network. Fast Ethernet, or 100Base-T operates at 100 Mbps, making it appropriate for applications which require more speed, such as transferring medium-sized files over the network, or running video on a few computers at the same time. Although many Fast Ethernet devices available today are designed to accommodate both standard and Fast Ethernet, the original standard Ethernet equipment is not able to handle the newer Fast Ethernet technology.
The most recent development in Ethernet technology is Gigabit Ethernet (GbE), sometimes called 1000Base-T, which operates at 1000 Mbps, or 1 Gigabit per second (1 Gbps). Gigabit Ethernet is the first version of Ethernet that allows many computers on a network to run video, multimedia, and heavy graphics software such as CAD/CAM applications and streaming media. And GbE equipment available today can often accomodate Standard and Fast Ethernet, as well as GbE.
If you are building your first network, think through which of the users on your network will requre standard, Fast, and Gigabit Ethernet before you begin shopping around for network hardware and software. Users who will not be using video, multimedia, or heavy graphics software might be satisfied with standard Ethernet. However, since 100Base-T equipment has now become more economical than even 10Base-T, it is recommended that 100Base-T be your minimum performance choice. Additionally, you should consider “future proofing” your network by providing higher-speed capability where you expect it to be needed in the future.
As networks have become more robust, the cable used in the network has also improved. For Ethernet networks, unshielded twisted-pair (UTP) cabling has become a standard. UTP cabling is copper cabling in which “pairs” of color-coded wires are used. The UTP cabling most often used in networks contains four pairs of wire. Typically, each pair is twisted together with a different number of twists per foot than any of the other pairs in the cable. This prevents the signals being carried on each pair from interfering with the signals of the other pairs.
The UTP cables most commonly used in Ethernet networks are Category 3 cable for 10Base-T and Category 5 cable for Fast Ethernet. With the advent of Gigabit Ethernet, the networking industry has scrambled to develop a cable — Category 5e — which can handle the additional stresses of sending data at Gigabit speeds. The most workable solution to emerge, however, has been the development of Gigabit Ethernet devices that can send data reliably over Category 5 cable. (See more about Gigabit over Cat 5.)
Another cabling standard is fiber optic cable. Fiber optic cable, while more expensive than copper cabling, has the advantage of being able to carry data much further than can copper. Fiber optic cable is ideal for carrying data between buildings, even up to 10 Km in some cases, compared to copper’s 100 meter limit. (See more about fiber.)
Which type of cabling is best for you? While standard Ethernet can be run on Cat 3, it is a good idea to “future proof” your network with Cat 5 cable. To keep costs at a minimum, reserve fiber for cable runs that are beyond what copper can do.
A network computer is connected to the network cabling with a network interface card, (also called a “NIC”, “nick”, or network adapter). Some NICs are installed inside of a computer: the PC is opened up and a network card is plugged directly into one of the computer’s internal expansion slots. Older computers have 16-bit slots, often called ISA slots. For these slots, a 16-bit ISA NIC is needed. Faster computers, like high-speed 486s and Pentiums, often have 32-bit, or PCI slots. These PCs require 32-bit PCI NICs to achieve faster networking speeds. The newest computers sometimes have 64-bit PCI slots, and can use either 32-bit or 64-bit PCI NICs. Either 32-bit or 64-bit NICs are appropriate for speed-critical applications like desktop video, multimedia, publishing, and databases.
Switches and Hubs
The last piece of the networking equipment needed to get started is the central connection point, usually a switch. Hubs have often been used in this application, but are becoming less frequently used due to their limitations.
In simplest terms, switches are boxes that are used to connect groups of PCs at a central location via network cabling. Today switches are available that can handle standard, Fast, and/or Gigabit Ethernet.
If you’re networking a small group of computers together, you can probably get by with a 10/100Base-T switch, some Cat 5 cables, and a handful of network adapters. Larger networks with more users than can be serviced by a single switch or hub will link multiple switches together, and then each switch, in turn, may connect a group of computers together using network cabling.
A plan of this kind allows you to build networks of tens, hundreds, or thousands of nodes.