Upgrading and Repairing Networks

Overview of the 802.11g Standard

The IEEE 802.11g standard is supported by both single-band 2.4GHz and dual-band (2.4/5GHz) hardware. It uses the same 2.4GHz frequency and channels as IEEE 802.11b, enabling an 802.11g client to connect to an 802.11b wireless network.

To achieve the superior speed of 802.11g networking, however, all network hardware, including network adapters, APs, repeaters, print servers, and bridges, must also be upgraded to 802.11g. An 802.11g-based AP can support 802.11b clients if it is configured for mixed operation.

Table 21.1 summarizes the differences between 802.11g and 802.11b wireless networks.

Table 21.1. Features of IEEE 802.11g and 802.11b Wireless Networks

Feature	802.11b	802.11g
Maximum data rate	11Mbps	54Mbps
Frequency band	2.4GHz	2.4GHz
Number of channels	11	11
Number of non-overlapping channels	3	3
Non-overlapping channels	1, 6, 11	1, 6, 11
Usual encryption standards supported	WEP	WEP, WPA

The newer 802.11g specification increases the bandwidth from 11Mbps (802.11b) in the 2.4GHz radio spectrum to 54Mbps. With backward compatibility built into 802.11g hardware, you can preserve your investment in IEEE 802.11b equipment when you incorporate 802.11g hardware into your wireless network.

But does 802.11b provide for your bandwidth needs? Consider that the basic bandwidth of 11Mbps is about the same speed you could obtain with a 10Mbps switched Ethernet wired network. A wired network consisting of 10Mbps (also known as 10BASE-T), if already installed, is considered legacy hardware.

It's likely that you have already moved as much of your wired Ethernet network as possible to 100Mbps (100BASE-T) speeds. In this situation you need to consider whether you really need wireless networking in your enterprise (or your SOHO). Because most users don't actually make full use of the 100Mbps that 100BASE-T enables, using 802.11g, despite its lower bandwidth, might be a cost-effective solution. This is especially true for mobile users.

Newer Gigabit Ethernet wired specifications are generally used for network backbone cabling, and have not reached the desktop except in a few instances.

For example, if your office only uses word processing, email, and spreadsheet software, the 11Mbps provided by 802.11b will probably suffice.

However, if you are using newer applications that require a larger bandwidth to satisfy users, such as graphic or other similar software, the difference between 802.11g (nominal 54Mbps data rate) and 100Mbps is not that great. Although 100Mbps is more than twice as fast as 54Mbps in actual throughput, you needn't consider 100Mbps unless your clients actually use the entire bandwidth! Even when transferring large amounts of data, 54Mbps (wireless) versus 100Mbps will probably not be noticed by your users.

In the rest of this chapter, I'll show you examples for installing an AP as well as a wireless network adapter card.