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Wireless all- In-One for Dummies- P3:I still remember when I got my first cordless phone. Suddenly, I didn’t have to run to the kitchen when the phone rang, I just carried the phone with me. I could make a phone call from wherever I was. Wireless meant freedom, and this is just a phone that I’m talking about! | Going over the Letters 39 Another benefit to the dual band radios is that you can run your 802.11n clients in the 5 GHz range and leave the 2.4 GHz band to the 802.11b g clients. This way you can make sure your speed-hungry devices aren t slowed down by legacy adapters. Compatibility concerns Wireless devices are generally downward compatible with other devices in the same frequency. Therefore you can mix 802.11b and 802.11g because they re both running at 2.4 GHz but not with 802.11a at 5 GHz. Keep in mind that just because something s compatible doesn t mean that it s going to run as well as it could. Even with an 802.11g card 54 Mbit s remember you re limited to 11 Mbps on an 802.11b network. When your access point s capabilities exceed that of the clients you still have problems. An 802.11g access point will instruct all clients to operate in a slower compatibility mode if even one 802.11b client is connected. 802.11n has some protections to prevent this problem with legacy clients but still is not as fast as an 802.11n only network. 802.11n will coexist with 802.11a as long as you ve got a dual band network card in your computer. This limitation isn t too much to worry about because 802.11a network cards aren t terribly popular. Table 2-1 helps you make sense of the information in this section. Book II 2 Choosing Hardware Table 2-1 802.11 Frequencies Speed and Ranges Standard Frequency Speed Range Should 1 Look at 1t 802.11 2.4 GHz 1-2 Mbps 100 No 802.11a 5 GHz 54 Mbps 100 No 802.11b 2.4 GHz 11 Mbps 150 No 802.11g 2.4 GHz 54 Mbps 150 Yes 802.11n Draft 2t 2.4 GHz 54-300 Mbps 300 Yes 5 GHz 54-600 Mbps 300 Yes If you go down the 802.11n path do your best to get dual band 2.4 GHz and 5 GHz equipment. Make sure any 802.11n gear you buy is certified by the Wi-Fi alliance. Check www.wi-fi.org for the latest version of the standard. 40 Purchasing a Brand Name At the moment 802.11g provides good speed and coverage and 802.11n expands on that. If speed is a concern go .
