Note: Before starting, be sure you have read the earlier papers and you understand what a hub, switch, router, and modem are and that you know the basics of Internet addressing.

With a wireless network you aren't tied down by cables and wires. A laptop, for example, in a wireless network can be used on the back patio or deck of the house to access a broadband Internet while enjoying nature at its finest. On a trip today you can sit in the lobby of many hotels and access their network hub and continue to work on your email without any direct network connection. If you live or work at a place where stringing network cables can't be done or done easily, the wireless network is the perfect solution.

Costs for a wireless network may run you somewhat more, in most cases, that the wired network but are dropping. You will need a wireless network adapter for each computer (except the main system) and a wireless access point (WAP) for the system. The converse, however, is that you don't need to run the wires for a wired network. In an existing building, the cost for running network wires can easily exceed the cost of the wireless networking. Even in a modern building such as the Seattle Central Library with over a 100 miles of telecommunications cable, the library still supports wireless networking over the entire building.

Introduction to the Wireless Network

The wireless network permits you to share files, printers, and other resources between computers without them being directly connected with each other. In fact, with the wireless 802.11 standard now defined, you can include wireless remote cameras (security), some Palm-Pilot ™ devices, print servers (print from the network without a computer, and a growing list of other devices.

Here are the most common wireless standards.

Note: Prices are dropping quickly for the access point hardware.

Remember that if a standard is 11 Mbps, that is not the throughput speed. The network also has to carry destination addresses, error correction information, acknowledgements, and more. For a 11 Mbps. network, the actual throughput speed of your data is 4-6 Mbps. (depending on distance, whether encryption is used, and other factors). For a 54 Mbps. network, it will be something like 15-22 Mbps..

The wireless system uses the 2.4 Ghz. multi-channel spectrum, the same spectrum that is used by some mobile phones, microwave ovens, and other devices. It requires no license. The wireless networking uses an additional protocol layer for its wireless transmission, known as the IEEE 802.11.

In the U.S., eleven channels are available in this spectrum. Unfortunately, these overlap some. Only three of these are free of overlap: 1, 6, and 11. Most manufacturers default to channel 6. If you experience interference, change to another channel.

• Networks using the "A" standard are as fast as those using the "G" standard, but their speed falls off more rapidly with distance. Unless all the systems are in the same room, the "A" standard is not much value. I expect it to fall in disfavor.
• Broadband Internet transmission is about 2 Mbps. or less. If your primary network application is using the Internet, a "B" standard is fine unless you are using more than four users, video, or moving large files (see below). This will save you some money unless you need the speed or security.
• For video transfer over a network, you will need the "G" standard.
• If you plan to move large files over a network, you should use the "G" standard.
• If you have more than four users on the network at a time, consider using the "G" standard. Remember the 11 Mbps. rate is divided among the simultaneous users on the network as all of them go through the access point. The faster "G" standard can support up to twelve.
• The "G" standard supports the WPA security, which is much, much better than the older WEP security used with the "B" standard. If security is a major issue, go with the "G" standard. With "B" systems, you can sometimes update the firmware to support the WPA. Since the firmware is copyrighted, if the manufacturer hasn't updated the firmware for WPA it hasn't been done. Moreover, even if you update the firmware you have no assurance the WPA will work correctly with these Pre-WPA systems. WPA takes more memory and is more computer-intensive. Also, you should have Windows 2000 or XP to use WPA. I don't recommend WPA for Windows 9x systems. More on this shortly.
• Some equipment using the "G" standard supports an accelerated speed, such as the Super-G supported by the Atheros chip (uses with D-link and others). This hardware supports speeds to 108 Mbps.. Throughput can approach 50 Mbps..
• If you are using your laptop in a coffeehouse or public area, most of these systems are "B". If your laptop is using a "G" system however, most laptops will still work with the "B" standard as well. Check when you buy.

There are several "G" systems (Super G) that use proprietary methods of boosting speed beyond the specified speed. One of the most popular strategies uses multiple channels to achieve their speed. If you are using this technology, we suggest you start with a single wireless computer and be sure there is no interference; that is, the high speed technology works for your area. If the speed boosting technology works for you, then buy the rest of the adapters. If there is interference, you will need to drop back to a normal "G" system.

Pros of Wireless Networking:

• No wiring is necessary between computers, giving a high degree of mobility.
• You can get access the Internet on the road or in offices of buildings already constructed in which rewiring is impossible or not cost-effective.
• Wireless is particularly convenient for laptops, permitting the user to operate without a power or modem cable to the laptop
• You can attach multiple devices to the network such as some PDAs, cameras, pads, etc.

Cons:

• Cost can be higher that with a wired network.
• The system is slower. Wireless networks are 54 Mbps. or less, whereas a wired system can be 100 or even 1000 Mbps. Distance is limited with a wireless, and speed drops with distance.
• Security can be an issue unless encryption is turned on (see below). Even then, it may not be adequate.

Remember that, unlike a wired system, multiple computer systems share the same channel. For example, in a wired system each cable to each network can support the full speed of the network. With a wireless router, you are broadcasting to all systems from often a single router. All systems, then, share the channel speed. As a result, the throughput is not only less than the wired Ethernet speed, but when using multiple computers will be less than a full wireless speed of the channel.

What You Will Need

Your shopping list for a wireless network should include:

• Broadband Modem for you Internet access (cable or DSL)
• Wireless Network Access Point with Router and Switch (WAP)
• Wireless Network Adapter for each computer that connects as wireless to the network
• Network Adapter for each computer that will connect as wired to the network.

You will need at least one wired computer in the network (100 Mbps.) to configure the wireless components. The wireless access point (with internal router and switcher) and the modem should be near this computer. You will need a NIC (adapter) card for this computer with an Ethernet connection. You will need CAT 5 cable for connecting the modem to the WAN connector of the WAP, and then another CAT 5 cable to connect the WAP port to your main computer.

Be sure all of your components adapters, routers, wireless access points, etc. have the WiFi logo on the outside. It should also say on the logo what standards are supported. All the components should be from the same manufacturer (see below).

The Router/Wireless Network Point/Multiple Port Switch (WAP) can be combined in a single unit. A wireless switch is really a hub, as frames sent by the WAP are received by all systems on the wireless network. The switch and the multiple ports on the WAP permits you to combine wired systems on the network with wireless systems with maximum bandwidth.

Be sure you purchase all of your components from the same manufacturer. There are multiple reasons for this:

• The IPs assigned by the DHCP to the local computers and other network components are not defined by the Ethernet standard and vary with the manufacturer.
• If you have a problem, different manufacturers cannot "past the buck" to another.
• If you are using a proprietary speed-up routine with the "G" standard, this is proprietary to the manufacturer. Other components probably won't work with it.
• If you plan to need to support roaming (walking around with your laptop still connected), you will need multiple access points. The technology to support roaming is not supported by the standards and is proprietary to the manufacturer if the manufacturer supports it. If you need multiple access points and roaming: Try to avoid the multiple access points by using high-gain antennas. Otherwise, stick to one manufacturer that supports it.
• For WEP encryption, the standard only supports a 64-bit key. The 128-bit key gives better encryption; but you can only trust compatibiility if equipment is all from the same manufacturer.

Remember to have patience when getting your network up. The WAP, which contains switches, takes some time to build its internal memory table. Computers have to have their network IPs assigned by the DHCP in the WAP. That takes time. If you turn the computers on and fail to see a system on the network check the Link lights on the cables and WAP to be sure the connection is good, then take a break and give the network a chance to see the new system.

The Two Modes

The wireless network can be installed in one of two modes: infrastructure or ad-hoc. Probably 95% of the wireless networks are installed as infrastructure, so if you don't know what you are doing that is a safe mode to choose. This means the wireless access network point acts as a hub for all devices on the network. Every computer communicates with the WAP - not directly with any other computer.

In an ad-hoc network, the computers can communicated directly with each other. An example might be a group of people in a conference room with their laptops, all functioning in their own network with each other.

First Step: Connect the Main Computer

Your first step is to get the networking going on the main computer. Install the network card for the main computer if it is not already installed. Normally you install the software first. Then you power down the computer and install the card. Then you power up the computer. The computer recognizes the new hardware and starts a plug-and-play cycle to install the card. Follow the directions of the manual with your card and the install paper to complete the installation of the card. Go to System | Hardware | Device Manager and check the network adapter entry (open the listing by clicking on the + sign there) and be sure your adapter is listed and there are no yellow or red flags on it before preceding. Then exit Windows and power down the computer.

Now hook up the modem, access point/switcher/ router, and the CAT 5 cable from the main computer to a WAP port. Connect the modem to the proper input (TV cable or telephone line). Connect the modem output to the WAN connection of the WAP. This connection may require a normal CAT 5 cable or crossover cable. Read your manuals or check with your salesperson to verify which type of cable to use. Connect first port on the WAP to your computer Ethernet port.

Turn on the modem first. Wait until the lights on the modem have stabilized.

Now turn on the WAP or router, as this is where your DHCP is that assigns all the IP addresses. Wait while it cycles through its diagnostics. When the router is ready, the WAN Link light on the WAP should be green.

Finally, bring up the PC. After it boots, you will need to start the browser and go to the configuration page by entering the address of the WAP configuration page into the browser address line. For the Linksys, this will be http://192.168.1.1. Follow the directions in your WAP manual for configuring the WAP. Here are some specifics:

• Be sure to change the default SSID. For a linksys, the default SSID is "linksys". Enter the desired SSID for you network here. It should be the same for all computers and components configured for your network.
• For the moment, turn on the broadcasting of the SSID. This will simplify configuring of the wireless systems. You should turn it off after everything is configured.
• For the moment, disable any encryption mode supported such as WEP or WPA. You will turn these on later after completing the installation.

Note: If your system fails to load the configuration screen, the most probable cause is a failure in the network install. Read our install page and verify on your network page that these are installed:

• Client for Microsoft Windows
• TCP/IP Protocol,
• The Adapter component for your card.

Other protocol components can be removed - they will slow down your network. There should be little external lights on the computer adapter card that should be on if the network is active.

Do not continue this first step is completed and you can access the Internet from your main computer.

Second Step: The First Wireless System

Install the network system on your first wireless system. If possible, this should be a laptop. You will see why in a moment. Install the network as with the main computer. Install the software for the network wireless card. Exit Windows, turn off the computer, then plug the card in. Turn on the computer and reboot. The Plug-and-play should recognize the card and install it. You need to use a configuration program now to set the adapter. In some cases the installation process also puts a configuration program on the computer. You can normally access this from an icon that is on the status bar at the lower right. If you are using XP, this operating system contains a configuration program that you can start from the Network Connections option on the Control Panel.

The computer should "see" the ID broadcast by your main computer and display a dialog box with the ID. If the card sees other IDs from other wireless networks in the area, you will see these as well. Select your ID and continue the configuration.

For now set the encryption off. Set the other options following the manual for your network adapter card.

Now - here is the advantage of the laptop as your first wireless system. Walk around with the laptop and get a feel of how far you can roam from your WAP. If you plan to install other computers on the network, verify each of these locations will work with your laptop. Desktop computers normally have better antennas than the laptop; but you do need to be sure the laptop will work where you want it to work. Also check the wireless network speed at the different locations.

If service is weak where you plan a desktop, you can often fix this by using a better antenna, such as a USB device with velcro clips, to improve the reception. In a worst-case situation, you can use a second wireless access point on a different channel or run a cable to the base WAP for wired access. Be sure this is all working before continuing. You may need to change equipment or channel.

Installing the Other Computers

Once the first wireless system is installed and working, continue and install others in the same way. Test and verify each system is working before continuing to the next.

Enable Security

Finally, take the final steps and enable encryption for each system.

Tip: When setting security, turn off all other systems except the main on the network that are not part of the wireless network. Set the encryption from the main (wired) computer, then bring each of the others on one at a time. Once set on one system, bring that computer down and go to the next.

WEP Encryption

For WEP use a 128 bit key. Some configuration programs permit you to enter a single keyword, and it creates the multiple keys from that. Don't use a dictionary word. Try using a keyword in an obscure language that you can remember.

Note: The WEP standard only supports a 64-bit key. Most WEP systems, however, can use a 128 bit key. If you are using equipment from more than one manufacturer, the 128 bit keys may not be compatible. In that case, you may have to get different adapters that will support the same standard or drop to 64 bit keys.

Set the key on the main system using the configuration program on the main (wired computer) again. Turn off the SSID broadcasting as well. Now go to each computer and set the same key and turn off the SSID broadcasting. The password shouldn't be any English word in the dictionary. If someone is trying to get in, they can use a program to go through all the dictionary words relatively quickly.

WPA Encryption

For WPA, there is a challenge here as you may be missing the supplicant program. This is a program the client adapter uses to ask permission from the WPA to join the network. It seems like it should be part of the client adapter driver, but it isn't. It has to be in the operating system. If it's not in the box with your client adapter, here is how to get it:

Windows XP - You can download it free from the Micrososft web site. Go to their Knowledge Base and download 815485. Follow the directions. It is free.

Windows 2000 - The only free one is at http//www.wirelesssecuritycorp.com/wsc/public/WPAAssistant.do

Also, be sure your operating system has all the update patches installed. For Windows 2000 this means having SP4 installed.

For WPA use a passphrase of at least 40 characters. The maximum length is 63 characters. Best alternative here is often a line of poetry that you can remember.

The wireless network you have now functions like a hub. Read our paper on hubs and switches in the library to see the difference and the disadvantage of a hub. If there are more than about four wireless users using the WAP on a "B" network, performance deteriorates. A "G" network can support about 12. If you have more than this, add another access point and set it to another channel that won't interfere with the first. If the first is set to Channel 6, the next should be at channel 1 or 11 (other channels overlap and will cause interference). This assumes, of course, that you aren't using a proprietary speed-up technology that uses multiple channels.

Use MAC Addressing for Security?

Most WAPs permit you to set up filtering on the MAC addresses. Each computer on the network has a MAC address set by hardware in the client adapter. You can enter these to a table in the WAP, and the WAP will only recognize packets from the systems with those addresses. Looks like a good way to stop those parking lot interlopers. Unfortunately, the idea isn't worth anything.

The MAC address, when sent through the system, is not encrypted. Any interloper can pick up the address and then use your system by pretending to be that MAC address. Although the MAC address is physically burned into the client adapter; software in the interloper's computer can simulate your computer by sending your MAC address from its software. The interloper can even de-associate the legitimate machine from the network, completely assuming the identity of the legitimate network machine.

In short, both WEP and WPA are much, much better and controlling security than the use of MAC address filterning.

Adding Other Network Components

You can add almost any Ethernet device to a network: printers, scanners, webcams,etc. Several PDAs are now supporting wireless networking. If you are purchasing a PDA for your network, be sure to check their power consumption for WiFi activity. WiFi cards consume a lot of power when doing WiFi. A few chipset manufacturers are producing WiFi chip sets with intelligent power management. Such chips drop the power requirements of the PDA when packets are not being transferred. Adding WiFi to a PDA can also make it bulkier. A PDA with an external battery pack and a expansion sleeve is not easy to carry around.

Note: There is another wireless technology called Bluetooth that is used by some PDAs. These PDAs use much lower power, but only transmit 30-50 feet and require a Bluetooth card in the PC. Bluetooth is also slower than WiFi and won't work with the WiFi hotspots. Don't expect to read your mail or surf the Web with Bluetooth at any hotspots - only with your own home computer.

Adding Legacy Systems

Your network, let's assume, is mostly new stuff with wireless G and a WPA that is supported. You have an old Windows 98 you wish to hook in from your old wireless B network that you use to be using. How do you do this? First, make sure the G your are using is not a new proprietary wireless that needs more than one channel. Put that network together and set it to channel 6. Plug your old B-standard WAP into a port on the new WAP with a CAT 5 cable. Set it to channel 1 and the legacy computer to channel 1. Use a different SSID for the old B WAP and the legacy computer than you are using the the G network. Keep the two WAPs at least two feet apart. Use WEP on the old B components, and WPA on the new ones.

Let us help you with your networking!

9/24/2004