Let's set the groundwork with some basics on networking hardware. The simplest way to connect your machines is to use an Ethernet hub. This simply broadcasts data across all its ports so that all machines receive all packets. You can also chain hubs together by plugging the link port from one into one of the data ports of another. Technically, hubs are known as Layer-1 switches, which is why you often see this label on hubs costing well under £10.
True switches are more complex. Layer-2 switches learn the underlying MAC address of each connected device and use this information to route data to specific ports rather than broadcasting across all of them. This method is more efficient and helps to keep documents secure by preventing people eavesdropping on unencrypted data meant for others.
Layer-3 switches are marked out by more sophisticated data switching functionality (including traffic prioritisation). They can talk to each other using special protocols that help decide the best route for each packet. Layer-4 switches include all of these features as well as network address translation and firewall capabilities. Domestic broadband routers are usually Layer-4 switches. At the top of the heap is the Layer-7 switch. These usually cost several thousand pounds and contain software to prioritise and route traffic based on application-specific criteria.
Sharing your Internet connection
If you're still using a single Windows XP computer linked directly to your broadband modem, and you want to give a second computer access to the Internet, you could upgrade to a dedicated broadband router. It may be cheaper, however, to use a network hub and simply activate Windows' Internet Connection Sharing (ICS) functionality.
When you originally installed your broadband drivers, the machine may have had ICS configured at the same time. On the Control Panel, double-click 'Network Connections'. The connection will say 'Shared' if ICS is configured. If so, there's nothing more to do. Plug in the second machine, boot it up and open a browser.
To configure ICS, double-click on the broadband connection to access its status. Click on the resulting 'Properties' button and click the Advanced tab. Click the tickbox marked 'Allow other network users to connect through this computer's Internet connection', press 'OK' and reboot your new machine. The new machine will be served an IP address from the gateway automatically when it boots up, because ICS has also turned the PC into a DHCP server.
Voice over IP
For Voice over IP (VoIP), all you really need is a set of speakers and a microphone – even the basic ones included with a laptop should do, so there's no need to purchase a handset or headset to get started. Most VoIP software is also free. Download Skype (www.skype.com) and you can be making calls in minutes.
PC-to-PC VoIP calls are usually free. As long as the person you want to call is registered with the same service, simply find their username in the directory and call them. VoIP providers usually charge you to place a VoIP call to a landline, however. The service will detect that you're calling a home phone and will connect you to its public switched telephone network (PSTN) exchange.
Before embracing VoIP, it pays to understand the drawbacks. If the power fails, for example, you'll be left without a phone until you plug your landline back in. The sound quality depends on your connection speed. If you're calling a dial-up computer from broadband, don't expect perfect CD-quality sound.
Instead of using the reliable but traffic-heavy TCP protocol to make calls, VoIP uses the less reliable but more lightweight UDP, which can't tell if packets are getting lost. This can lead to 'stuttering', where the signal drops out or becomes garbled. To help overcome stuttering, you'll need a broadband router that supports QoS (Quality of Service). Use this to set VoIP packets to a higher priority than other traffic. This should make your conversations as stutter-free as possible.
