How to set up a home network and share a broadband connection



Many people with a broadband Internet connection at home want to share it so that you can access the Internet on each computer in your household. The equipment to do this is now available very cheaply, but people are often put off setting up a network as they don't know where to start. It is fair to say that setting up a network at home is not exactly plug and play - you can't expect to just plug everything in without reading the manual and it to just work. However it isn't rocket science either - anyone should expect to be able to set up a network if they are prepared to spend just a little time understanding what is going on and reading the instructions.

This guide is not intended to describe exactly how to set up a home network step by step - needs differ and we can't give exact instructions to suit everyone. It is intended to give a background explaining the technology, help you work out what equipment you need and give suggestions about where to purchase it. You can then follow the instructions provided with the equipment you buy in order to set it up.

This guide covers setting up a home network using Ethernet networking. Ethernet is a long-established networking standard, and ethernet equipment is cheap and easily available. Ethernet does require running new cabling to each computer you need to connect to the network. Some other alternatives are available which use carry signals using radio waves or power cables within the home: Wireless Ethernet (WiFi) or HomePlug Networking. These are great fro some but not everyone. WiFi has limited coverage - it won't cover from one corner to another in a large house. HomePlug works very easily, but can get expensive if you have a lot of people needing to use it (you have to buy an adapter for each).

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Understanding network equipment

To set up a home network you need to understand what function each piece of equipment performs so you can connect them together correctly. The jargon used can be confusing, but this glossary and diagram describes the key equipment and what it does.

Note that while these components are described and illustrated separately for clarity, in practice you can often buy one box which combines two or more functions (for example a router will often include a built-in switch too).

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Illustration of a typical home network

image of the various components in a home network

image of the various components in a home network

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Component What it does
ADSL Modem Translates the high frequency broadband signals carried on your phone line into data signals your computer or home network can understand. In the UK most ADSL services use a cable modem which connects directly to a USB socket on the PC. If you want to share your ADSL connection you need to replace the ADSL modem with an ADSL router instead.
Cable Modem Translates the broadband signals carried over the Cable TV network into data signals your computer or home network can understand. Virgin Media provide a cable modem as part of their broadband service, you don't need to buy it. For a cable modem connection to a single PC the cable modem connects directly to an ethernet adapter in the PC. To share the connection you need to connect it to a router instead.
NAT Router (Gateway) A NAT router, sometimes also known as a gateway, maps the single IP address on the Internet assigned by your broadband provider into multiple private IP addresses for use by all the computers on your home network. This mapping is done using a technique called NAT (Network Address Translation). Routers also include a DHCP server. DHCP means that you can set the TCP/IP settings of other computers on the network to 'obtain settings automatically' and they will pick up the correct addresses to use. A router also acts a firewall, providing some basic protection against intruders on the Internet trying to access your computer.
A router has at least two ports, a WAN (Wide Area Network) port that connects to your cable modem or ADSL modem, and a LAN (Local Area Network) port that connects to your home network. On the WAN side, some routers have an ethernet interface to connect to a cable modem. Others include the functionality of an ADSL modem too, so they connect directly to an ADSL-enabled phone line. On the LAN side, routers have at least one ethernet interface which you connect to a switch. However many routers have a built-in switch (i.e. they have more than one LAN port).
Ethernet switch (or hub) An ethernet switch sends network traffic to the correct destination on the network. You need a switch with at least one port for each computer. If you run out of ports on the switch you can connect switches together to add more ports.
You can use an ethernet hub instead of a switch. They do exactly the same thing, but hubs are slower when used heavily. Hubs used to be cheaper, but now the prices of hubs and switches are so similar you might as well get a switch.
Ethernet Adaptor Needed in each computer connected to an ethernet switch. Most computers have built-in ethernet sockets.
Ethernet Cable Cable which runs between the switch and ethernet adapters. You might see it referred to as Cat5 or Cat5e cable, these are the standards that show a high quality cable (almost all ethernet cable on sale meets these standards). Ethernet cable ends in a connector called an RJ45 plug.
You can buy ethernet cable in varying lengths with RJ-45 plugs already fitted. For temporary installations we recommend buying pre-made cables of the right length or slightly longer. For permanent installations get the cabling installed professionally by a contractor. It is possible with the right tools to buy cable on the reel and fit the RJ45 plugs yourself but we do not recommend that. It is not as easy as it seems to fit - you can end up with poorly performing or non-functional networks due to small mistakes in the cabling.
Ethernet Cable Joiner Quick and easy way to join two ethernet cables together to provide a longer length. As a rule of thumb, use up to three cables and two cable joiners in any run of cabling. More than two joiners in the same run can cause problems.
Crossover Ethernet Cable You normally need a special ethernet cable, called a crossover ethernet cable, if you need to connect two switches together. Crossover cables look like ordinary ethernet cables but are wired differently internally - the 'transmit' and 'receive' pairs are crossed over. However some modern switches (such as the switch recommended here) will work with either standard or crossover cables automatically. Get one of those switches as it is one less thing to worry about.

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Summary of equipment needed

A router

If you have this broadband service Buy How it works
Virgin Media Broadband (or other broadband service with an ethernet interface, such as ResNet ethernet). An integrated Router & Switch.
You plug your existing cable modem supplied by Virgin into the router. Your original computer and any new computers then plug in to the switch ports on the router via ethernet cables. The router translates the single IP address assigned by your provider into multiple private IP addresses for each computer on your home network. As a form of security, Virgin use 'MAC Address Authentication' - this means that the cable modem only works with the MAC address built-in to the ethernet adapter in your computer. To get the router working you need to use the 'MAC address clone' feature so that the router has the same MAC address as your computer.
ADSL connection via a BT phone line (using an ADSL modem with a USB interface) An integrated ADSL Modem, Router & Switch.
Currently you will have an ADSL modem connected to a single PC via USB. You no longer need the USB ADSL modem. Instead plug the integrated ADSL modem/switch into your ADSL-enabled phone line. You then connect your original computer and any new computers to the switch ports in the router using ethernet cables. The router translates the single IP address assigned by your provider into multiple private IP addresses for each computer on your home network.

Not sure which router to get? Shops like PC World display them in two sections depending on whether you get your boradband via a BT phone line or via a cable provider. This makes it easy to get the right one.

Also needed - ethernet cables

  • Ethernet cables. You need cables of sufficient length to run from the switch to each computer on the network. These cost approx 0.50 - 1 per metre.

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Use with the UoB virtual private network

Many users with a broadband connection at home find it useful to connect to the UoB virtual private network (VPN), which provides access to University network resources from home by establishing a VPN. There are some problems with accessing a VPN via a router, especially if more than one person on your home network wants to connect simultaneously.

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Further Information

The following websites have useful tutorials about home networking:

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If you have problems

  • Read the documentation provided with the router and other equipment carefully.
  • Phone the support line for the manufacturer of the router. They are best placed to troubleshoot any problems.
  • Phone your broadband provider's support line.
  • Employ a firm or individual who specialises in this - see our listing of external sources for home IT support.

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