PC Components

Before the discussion turns to the actual network hardware, there maybe a need to determine what network adapter can be installed in a particular machine. Three types of card types are available, ISA, EISA and PCI. Almost all modern Intel PCs will have PCI and EISA slots, whereas older machines may have just ISA or ISA and PCI. Pictured below is the expansion card carrier from this actual PC. It is removable from the machine (yes, I turned it off first!), and is really quite good for displaying the differences between the different slots. This machine has EISA and PCI slots, and has just the one slot used for the network card.

Notice that the two sets of slots seem to interleave? The two middle slots are either PCI or EISA, both cannot be used at the same time, so this PC can only have a maximum of six additional cards installed.

Some Network Cards

	Very common 3Com ISA Ethernet adapter that supports only RJ45 type ethernets. It is also 10M HD speed. This type of card is quite readily picked up second hand at computer fairs, tho' beware they will be second-hand.
	3Com EISA 10M card supporting just 10base2 and 10base5 interfaces, which, to be fair are not much use in the modern networked home, the latter especially;-) It is highly unlikely to be used in the home networking environment as it is very cumbersome.
	A 3Com PCI card that can be used on practically all ethernet types, albeit at 10M only. This card, like the others, may look a bit on the ancient side compared to the nice Netgear card in the chassis above, but all three work happily in Win9X, NT, Linux and Solaris for Intel, tho' you may need to download the relevant drivers from 3Com, or switch off the plug and play feature if the card features it and the OS requires it (Linux, definately). They all probably work with BSD variants as well, but this untested as yet.

Network components

Hubs and Switches

The network components consist mainly of the hubs, switches, routers (and whatever else you fancy hooking up there), that allow your machines to connect and talk to other machines, be they on the same network, or, on the other side of the world. There are hundreds of types of devices available, from budget manufacturers such as Netgear (extremely good kit, IME) up to major equipment manufacturers such as Alcatel (every home deserves an OMNI Switch, I reckon;-)) and they come in a combination of sizes and functionality. Unfortunately, I don't have an OMNI Switch so you'll have to deal with the Netgear instead.

Small and compact, this particular hub (Model EN-104) can accomodate up to four devices, with one of the ports selectable for normal/cross-over operation. This is identified in the diagram as uplink, and it has a push-button located adjacent to it so that the operation can be manually set. You would only need to use the uplink facility, however, if you were connecting a router, or another hub, to the hub and an actual cross-over cable was not available. This particular Netgear hub also has additional connectivity features in that it also has a BNC connector on the reverse for a 10base2 connection (see 10base2 below), and this can be used to connect existing 10base2 LANs to the RJ45 Media that is required by the Cable Modem.

Switches perform a similar function to hubs, but they have slightly more intelligence and can accomodate devices with differing speeds, so you could have a 100M device connected to one port and a 10M device connected to another. In addition switches differ from hubs in the way they distribute the data between devices. A device sending data through a Hub, will have it's data sent to every device attached the same hub. The same device connected to a Switch will find it's data only being sent to the destination device. The Switch does this by only sending the data to just the destination MAC address, rather than sending it to all.

The following diagrams illustrate the difference in data distrubution when a hub is used compared to a switch.

Cabling Types 10baseT

10baseT, or Twisted Pair Ethernet is the modern equivalent of 10base2 cable systems. Far more flexible, neater and less prone to network faults, TP appears on a myriad of networking and communications equipment. If you have your single PC already connected to your CM then you are already using RJ45 TP cabling and it will almost probably feature in your network. CAT5 cable consists of 4 pairs of wires, with each pair being two insulated copper wires twisted together. These 'twisted-pairs' are then sheathed in a plastic outer sleeve that come in a variety of colours. RJ45 refers to the connector that is crimped onto the end of the CAT 5 cable. The connector is rectangular in shape and has a tab at the top. The cable is inserted so that the tab latches onto a small recess in the socket.AN RJ 45 cable plugged into an RJ45 socket on a hub.

10base2

10base2 cabling consists of 50ohm coaxial cable terminated in BNC plug. This plug is a push and twist type, that latches onto lugs on the BNC socket of a compatible device. 10base2 cabling also requires that a cable exists between each device attached, which results in all the devices forming a daisy-chain. The 50ohm impedence of the cable must be maintained throughout the network and terminators are required at each end of the network. A close-up of a 10base2 T-piece with a terminator is shown.

Wireless Lans

Both of the the network types above require a cable connected between the hub or switch and each device. This can be restrictive unless it is possible to hide cables away, and also how difficult it is to run a cable from the hub to where the PC is. An alternative way to network a number of PCs is use wireless networking. Wireless networks use radio to transmit and receive data. Each PC still has a network card installed, but the 'physical' medium used to connect the devices is now an aerial at each end.

Wireless LANs can support upto 11MBps connection speeds, but this is dependant on the distance between the two devices transmitting to each other.