Do You Need a Wireless Network?

After comparing wireless 802.11 networking to cabled network technologies, how do you decide which is best for you? A number of factors should be considered .

A large enterprise with hundreds, or perhaps thousands, of computers will obviously need a large wired network, with LANs connected by ATM, Frame Relay, and other switched network technologies. Deciding where to use Access Points at some locations is a choice to be made by

The need for wireless networking at that point
Distance limitations
The security considerations associated with the placement of the Access Point

In Chapter 23 you will find a discussion of the security implications of using a wireless network, and how encryption and authorization mechanisms can be used to make the network secure.

If a wireless network is needed strictly for peripheral or folder sharing in a small business, an ad hoc wireless network (no AP is needed) is sufficient. However, if the wireless network must be connected to an existing wired network or to the Internet, an AP must be added to the network. You can use an AP with an integrated router and 10/100 Ethernet switch instead of a separate AP, Ethernet switch, and router.

Some businesses require the most stringent security requirements, using other technologies that are discussed in Chapter 24, "Overview of the TCP/IP Protocol Suite," as well as virtual private networks, covered in Chapter 46, "Virtual Private Networks (VPNs) and Tunneling."

Connecting the Wireless Network to a Wired LAN

In Chapter 18, "Introduction to Wireless Networking," you learned that you can create an ad hoc wireless network by using a collection of computers. When you use an AP to mediate communications between the wireless clients , you create an infrastructure network. When you're using a few laptop computers in a temporary location, an ad hoc wireless configuration may suffice.

However, if you are going to connect your LAN to the Internet, an AP is required to connect the LAN to the cable/DSL modem or another Internet connection.

If the wired network or broadband connection operates at a faster bandwidth (and most do today, with 100Mbps being the lowest common denominator for wired networks), the AP can buffer between the lower-speed wireless network and the 100Mbps wired network.

If your AP does not include an Ethernet switch, you can connect the AP to an unused port on an existing Ethernet switch. Whether an AP has an integrated Ethernet switch or the AP is connected to an existing switch, wired and wireless clients can be part of the same network. By configuring wired and wireless clients with the same workgroup name or by using the same domain controller, they can become part of the same network, sharing printers, an Internet connection, and folders.

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.

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Ogletree T.W., Soper M.E.

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