Chapter 5: Choosing Wireless Home Networking Equipment 91
router and a network switch — a wireless gateway like we define in Chapter 2. To efficiently connect multiple computers and to easily share an Internet connection, you need devices to perform all these functions, and purchasing one multi-purpose device is the most economical way to accomplish that.
DHCP servers
To create an easy-to-use home network, your network should have a Dynamic Host Configuration Protocol (DHCP) server. A DHCP server dynamically assigns an IP address to each computer or other device in your network. This function relieves you from having to keep track of all the devices on the network and assign addresses to each one manually.
Network addresses are necessary for the computers and other devices on your network to communicate. Because most networks today use a set of protocols (Transmission Control Protocol/Internet Protocol, or TCP/IP) with network addresses (Internet Protocol [IP] addresses), we refer to network addresses as IP addresses in this book. In fact, the Internet uses the TCP/IP protocols, and every computer that is connected to the Internet must be identified by an IP address.
When your computer is connected to the Internet, your Internet Service Provider (ISP), such as America Online (AOL) or EarthLink, has assigned your computer an IP address. However, even when your computer isn’t connected to the Internet, it needs an IP address to communicate with other computers on your home network.
The DHCP server can be a standalone device, but it’s typically a service provided either by a computer on the network or by a network router. The DHCP server maintains a database of all the current DHCP clients — the computers and other devices to which it has assigned IP addresses — issuing new addresses as each device’s software requests an address.
Windows, Macintosh, and most other types of computers — as well as network devices — can automatically communicate over the network with a DHCP server to request the server to issue an IP address.
Gateways, NAT, and cable/DSL routers
A wireless gateway is a wireless AP that enables multiple computers to share the same IP address on the Internet. This fact would seem to be a contradiction because every computer on the Internet needs its own IP address. The magic that makes an Internet gateway possible is Network Address Translation (NAT). Most access points that you buy today are wireless gateways.
92 Part II: Making Plans
When your wireless network needs some order
Your home network comprises many parts. If you’re smart, you’ve consolidated these as much as possible because having fewer devices means easier installation and troubleshooting. But suppose that you have a cable modem, a router, a switch, and an access point — not an unusual situation if you grew your network over time. Now suppose that the power goes out. Each of these devices will reset at different rates. The switch will probably come back fairly quickly because it’s a simple device. The cable modem will probably take the longest to re-sync with the network, and the AP and router will come back up probably somewhere in-between.
The problem that you, as a client of the DHCP server (which is likely in the router in this instance), have is that not all the elements are in place for a clean IP assignment to flow back to your system. For instance, the router needs to
know the WAN IP address in order for you to have a good connection to the Internet. If the cable modem hasn’t renegotiated its connection, it cannot provide that to the router. If the AP comes back online before the router, it cannot get its DHCP from the router to provide connectivity to the client. Different devices react differently when something is not as it should be on start up.
Our advice: If you have a problem with your connectivity that you didn’t have before the electricity went out and came back on, follow these simple steps. Turn everything off, start at the farthest point from the client, and work back toward the client, letting each device get its full startup cycle complete before moving to the next device in line — ending with rebooting your PC or other wirelessly enabled device.
A device that typically provides the NAT service to a home network is called a cable/digital subscriber line (DSL) router or broadband router. (Note that you can also purchase a broadband modem that doubles as a router, but the typical modem is not a router.) Cable/DSL routers used in home networks also provide the DHCP service. The router communicates with each computer or other device on your home network via private IP addresses — the IP addresses assigned by the DHCP server. (See the earlier section “DHCP servers.”) However, the router uses a single IP address — the one assigned by your ISP’s DHCP server — in packets of data intended for the Internet.
In addition to providing a method of sharing an Internet connection, the NAT service provided by a broadband router also adds a measure of security because the computers on your network aren’t directly exposed to the Internet. The only computer visible to the Internet is the broadband router.
This protection can also be a disadvantage for certain types of Internet gaming and computer-to-computer file transfer applications. If you find that you need to use one of these applications, look for a router with features called DMZ (for demilitarized zone) and port forwarding that expose just enough of your system to the Internet to play Internet games and transfer files. (Read more about this in Chapter 12.)
Chapter 5: Choosing Wireless Home Networking Equipment 93
A wireless Internet gateway is an AP that’s bundled with a cable/DSL modem/ router. By hooking this single device to a cable connection or DSL line, you can share an Internet connection with all the computers connected to the network, wirelessly. By definition, all wireless Internet gateway devices also include several wired Ethernet ports that enable you to add wired devices to your network as well as wireless devices.
Switches
Wireless gateway devices available from nearly any manufacturer include from one to eight Ethernet ports with which you can connect computers or other devices via Ethernet cables. These gateway devices are not only wireless APs but are also wired switches that efficiently enable all the computers on your network to communicate either wirelessly or over Ethernet cables.
As we discuss in Chapter 2, there is a huge difference in performance between a switch and a hub. Just because a device says that it has four ports or eight ports doesn’t mean that it’s one or the other — it could be either. Look for words like switched LAN ports for an embedded switch in the device.
Even though you might intend to create a wireless home network, sometimes you might want to attach a device to the network through a more traditional network cable. For example, we highly recommend that you configure an AP for the first time with the AP attached by a network cable directly to your computer. At times, it might also be convenient to connect one of the other computers in your home directly to your AP.
Print servers
A few multifunction Internet gateways add a feature that enables you to add a printer to the network: a print server. Next to sharing an Internet connection, printer sharing is the most cost-effective reason to network home computers because everyone in the house can share one printer. Wireless print servers have become a lot more economical in the past few years. However, when the print server is included with the Internet gateway device, it’s suddenly very cost effective.
The disadvantage of using the print server bundled with the AP, however, is apparent if you locate your AP in a room or location other than where you’d like to place your printer. Consider a standalone print server device if you want to have your printer wirelessly enabled but not near your AP.