Ethernet Networks
Most people think of Ethernet when they think of networks because Ethernet was one of the first and most popular network technologies. The components you need for an Ethernet LAN are network interface cards (NICs) for your computers, Ethernet cabling and a central hub.
There are several Ethernet standards or protocols which support different speeds and use different types of cables. One of the original standards 10Base2 uses thin coaxial or "thin Ethernet" cable which looks like a smaller version of your TV cable. In a thin coax network the computers (up to 30) are connected in series to a common central cable or bus. This arrangement, referred to as bus topology, doesn't require a hub. 10Base2 is an older, less flexible standard and is falling out of use.
The most popular type of Ethernet networks use twisted pair cable which is like the telephone wire inside the walls of your home. The cable is thinner and more flexible than thin coax but not as well shielded from electromagnetic interference. Twisted pair cables come in five categories. CAT3, 4 and 5 cables used for Ethernet networks have RJ-45 connectors that look like large telephone jacks.
CAT3 and CAT5 cable is the most common and transfer data at a maximum of 16 Mbps and 100 Mbps respectively. Twisted pair cable can be either unshielded (UTP) or shielded (STP). The latter type of cable has a metal layer that cuts down on electromagnetic interference in noisy environments. UTP is used in most home LANs because it's inexpensive and interference is uncommon.
In both the 10BaseT (10 Mbps) and 100BaseT (100 Mbps) Ethernet standards, the "T" stands for twisted pair cable. A 10BaseT network can be wired with either CAT3 or 5 cables, but a 100BaseT network requires CAT5. These two Ethernet standards use a star topology where each computer is connected to a central hub. Hubs are hardware devices with multiple ports that act as central connection points in a network. Typically, connecting more than two computers in an Ethernet network requires a hub.
However you can connect two computers directly to each other without a hub using a special UTP crossover cable. This is less reliable but cheaper than a hub network. Gamers can use this expedient method for head-to-head play with quick response time. Crossover cables are also used to connect hubs together. A crossover cable is $5-25 in price depending on length.
Hubs
With more than two computers you'll need a hub; these devices vary in size, speed and number of ports. The average home network uses a 10BaseT system with a 10 Mbps hub. For 100BaseT (Fast Ethernet) networks, you'll need a 100 Mbps hub. Dual speed 10/100 Mbps hubs with auto-sensing allow users to use either speed.
Hubs have multiple ports from four to over 20 on a single device. For each port, the hub has an indicator light so if a segment of cable or NIC stops functioning you can figure out which computer has the problem. A star topology network with a hub will continue to function even when one of the connections goes down.
For a home LAN, you'll probably use a stand-alone hub with 4 to 12 ports. Stand-alone hubs can be linked together to expand your network. Larger networks use stackable or modular hubs which can accommodate many more computers. Look for a standard, inexpensive hub rather than a managed one which comes with advanced features required by larger networks.
A 10 Mbps hub with 4-5 ports can cost between $60-120. An 8-port model is roughly $130-160. A dual 10/100 Mbps hub will be costlier than a 10 Mbps hub with the same number of ports. Faster 100 Mbps hubs are the most expensive. You can usually save some cash by getting a home networking kit which typically includes a small 4-5 port hub plus NIC cards.
Switches
Switches are devices that perform the same function as hubs but operate more efficiently. When you send data through a hub it's forwarded to the entire LAN then read by the computer it's intended for. A switch sends data only to the computer it's addressed to, reducing network traffic and expanding capacity. Hubs can either send or receive data but can't do both at the same time. With a switch, a computer can simultaneously send and receive data, increasing the speed of the network. Switches used to be more expensive than hubs, but some kits now offer a switch at the same price as a hub.
Network Interface Cards (NIC)
To link computers together in a network, each machine needs a NIC. Network cards are usually designed for a specific type of network protocol (Ethernet, Fast Ethernet) and media (type of cable). Some cards can support multiple protocols or multiple media. For example, you can get cards that have both RJ-45 and BNC ports for either twisted pair or thin coax cable.
Some PCs come with NICs built-in but most require the addition of a card using either an ISA or PCI expansion slot. What you choose will be dictated by the type of expansion slots you have available. The PCI interface is more efficient, but older computers may not have free PCI slots. Laptops can use NICs that fit into the PC card slot.
Cards come in multiple speeds: 10 Mbps, 100 Mbps and 10/100 Mbps. Ordinarily, the speed of the NIC should match the LAN speed, but it's possible to connect a computer with a 10 Mbps card to a 100 Mbps network. NICs also have different bus widths which determine how much data can be transferred to and from your computer at one time. The greater the bus width the better. Cards range in price from $20-$300 with faster 100 Mbps and 10/100 Mbps NICs being more expensive.
Another way of connecting to an Ethernet LAN is with a USB-to-Ethernet adapter. These adapters let you add a computer to an existing Ethernet network without adding a NIC. The adapter attaches to a computer's USB port on one end and an Ethernet cable on the other. However, the adapter can only transfer data at 4 Mbps which doesn't take advantage of the full networking speed of Ethernet.
Ethernet Kits
Manufacturers are making it easier to set up a home Ethernet LAN by offering kits. These kits usually include a small 4-5 port hub, two NICs, cabling and software. Prices for a 10 Mbps kit start around $70 while 10/100 Mbps kits start around $150. Of course, you can always buy the components separately. Unlike wireless network products, Ethernet products from different manufacturers are completely compatible. A good kit should also include instructions for installing hardware and configuring your operating system for network access.
Mac Networks
Macs have had basic networking capabilities ever since they had hard drives. All Macs come with a built-in networking protocol called AppleTalk. Macs can use AppleTalk over an Ethernet or Local Talk network. Local Talk connects older Macs via their modem or printer serial ports. Newer Macs usually have built-in Ethernet adapters.
Local Talk
Local Talk networks use either Mac printer cables or ordinary phone cord. If you have several Macs or peripherals to connect, you can daisy-chain the devices with phone cord (RJ-11) and Phone Net adapters. These plug into a serial port (usually the printer port) on one end and have two phone jacks on the other. Local Talk only transfers data at 230 Kbps which is a far cry from Ethernet, but printer cables, phone cord and Phone Net adapters (about $20) are inexpensive. Macs with Ethernet but no printer ports can be connected to a Local Talk network with an ethernet-to-LocalTalk adapter.
Mac Ethernet
If you own an older Mac, it may not have an Ethernet card. Check the model you have and see whether it has an open expansion slot. Some Macs require Ethernet cards that are specific to that model; others can use cards for the NuBus or LC Communication slots. Older Power Macs and Quadras with built-in Ethernet use a proprietary connector called an AAUI port. An external adapter or transceiver is required to connect a standard Ethernet cable (coax or twisted pair). All newer Macs like the Power Mac G3, G4 and iMac ship with built in Ethernet cards with standard RJ-45 connectors.
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