Dual-Mode Access Points

The next chapter covers IEEE 802.11a. This standard enables data rates up to 54Mbps. A dual-mode Access Point operates using both technologies (some support 802.11a and 802.11g), and can buffer data between the lower and higher data rates. Dual-mode Access Points cost more than an Access Point that works with just one technology.

A dual-mode Access Point can be useful in several situations:

• In expanding an existing 802.11b network. For example, if you have already invested in 802.11b devices, but want to use the faster 802.11a technology when you add newer devices to the network, a dual-mode Access Point can enable all devices to interact with each other.

• In providing an upgrade path for your wireless network. Again, if you have already invested in 802.11b equipment, a dual-mode Access Point can enable you to slowly replace these devices with 802.11a as your budget permits. In a large network, it can be expensive to change out all of your network adapters as well as Access Points at the same time.

• In providing access to temporary network clients. If a business client, a consultant, or another person visits your site and brings his own wireless computer (such as a laptop), then a dual-mode Access Point enables that person to make a connection to your network no matter whether he uses 802.11a, 802.11b, or 802.11g.

Note

You don't need a dual-mode AP to support 802.11g and 802.11b clients on the same network. Both clients use the same 2.4GHz frequency band, so an 802.11b client can connect with an 802.11g AP, and an 802.11g client can connect with an 802.11b AP. Most mixed-mode networks run at the speed of the slowest client or AP, though. Thus, standardizing on 802.11g hardware provides a faster network than one which mixes 802.11b and 802.11g hardware.

The next chapter will give you an overview of 802.11a networking, and Chapter 21 covers a newer standard, 802.11g. Chapter 21 also shows how to configure these clients.