Building a local network
Before we can put our computers onto the internet, we have to network them all together.
Then we'll connect our network to their network, they being your ISP. That will put all our computers onto the Internet. Connecting your lan to your ISP is another topic.
Network Physical Layer
When we think of a local network, we usually are thinking about a kind of interconnect - usually wires. By far the most common kind of local network is an Ethernet, carried over twisted pair wires. This kind of network is called a 10BasetT (or 100baseT) network. The wiring consists of phone-like wires, 8-pin modular connectos called "RJ-45", and round cables, usually blue or yellow.
There are several other kinds of cabling systems used for Ethernet, but they are not common any more, so we'll ignore them. There are other kinds of networks besides Ethernet, too. But they also aren't common. The thing that's quickly gaining ground as a interconnect medium instead of twisted pairs is wireless
(like Apple's Airport) If you go with wireless, then you don't need to worry about wiring much at all. Each machine in your local network will need an appropriate interface card, however.
If you choose to use conventional Ethernet, then what you need is:
- Each machine needs an Ethernet card or built-in Ethernet with an RJ-45 connector.
- A wiring path needs to exist from each machine to an Ethernet Hub. (Note: if you are only connecting one machine to another, and not connecting either of them to anything else, then you do not need a hub. You just need a cross-over cable
between the two machines.)
- Each machine needs to be set up to do tcp/ip over the ethernet card. On pc, use the network control panel to do this and then call Bill for instructions. On a Mac running OS 9 or earlier, open the TCP/IP control panel, and choose Ethernet as the path. On a Mac running system X, it will automatically use whatever is active.
- Each machine needs an IP address and netmask.
These are set in the network control panel. Generally, you can just sit it to get IP address automatically. It will either get an address from a DHCP server
on the network, or self-assign an address. (Self-assigned addresses start with 169. so you can recognize them.)
Ethernet Wiring
If you're going to run wires, then the setup will look something like this:
If you're using one of the newer non-cabled systems, then it will look much the same, but you will use a special interface instead of connecting your machines to a wall jack, and you will use a different kind of hub.
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Mail John
21 April 2000