CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [431]
Figure 24-10 AT&T USBConnect Mercury 3G
In areas with broad cell phone coverage, such as big cities, cellular wireless networks offer high-speed access (around 1.5-Mbps download speeds) anywhere you go. Carriers use many protocols to provide the higher speeds, and collectively they are known as 3G. Just fire up your smartphone or portable computer and start surfing the Web! In remote areas where the 3G networks have not been built out, the speed drops down to something closer to modem connection speeds. (See Chapter 25, “The Internet,” for the scoop on modems.)
Cellular networks use various protocols to connect, such as Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), and Code Division Multiple Access (CDMA). The 3G networks make use of protocols such as UMTS/HSPA (AT&T), EV-DO (Verizon), and UMTS (T-Mobile). These protocols are handled seamlessly by the software and hardware. What end users see is TCP/IP, just as if they connected through a wired network.
Practical Application
Installing and Configuring Wireless Networking
The mechanics of setting up a wireless network don’t differ much from a wired network. Physically installing a wireless network adapter is the same as installing a wired NIC, whether it’s an internal PCI card, a PC Card, or an external USB device. Simply install the device and let plug and play handle detection and resource allocation. Install the device’s supplied driver when prompted, and you’re practically finished. Unless you’re using Windows XP and later, you also need to install the wireless network configuration utility supplied with your wireless network adapter so you can set your communication mode, SSID, and so on.
As mentioned earlier, wireless devices want to talk to each other, so communicating with an available wireless network is usually a no-brainer. The trick is in configuring the wireless network so that only specific wireless nodes are able to use it and securing the data that’s being sent through the air.
Wi-Fi
Wi-Fi networks support ad hoc and infrastructure operation modes. Which mode you choose depends on the number of wireless nodes you need to support, the type of data sharing they’ll perform, and your management requirements.
Ad hoc Mode
Ad hoc wireless networks don’t need a WAP. The only requirements in an ad hoc mode wireless network are that each wireless node be configured with the same network name (SSID) and that no two nodes use the same IP address. Figure 24-11 shows a wireless network configuration utility with ad hoc mode selected.
The only other configuration steps to take is to make sure that no two nodes are using the same IP address (this step is usually unnecessary if all PCs are using DHCP) and ensuring that the File and Printer Sharing service is running on all nodes.
Infrastructure Mode
Typically, infrastructure mode wireless networks employ one or more WAPs connected to a wired network segment, a corporate intranet or the Internet, or both. As with ad hoc mode wireless networks, infrastructure mode networks require that the same SSID be configured on all nodes and WAPs. Figure 24-12 shows a NETGEAR Wi-Fi configuration screen set to infrastructure mode and using WPA security.
WAPs have an integrated Web server and are configured through a browser-based setup utility. Typically, you fire up your Web browser on one of your network client
Figure 24-11 Selecting ad hoc mode in wireless configuration utility
Figure 24-12 Selecting infrastructure mode in wireless configuration utility
workstations and enter the WAP’s default IP address, such as 192.168.1.1, to bring up the configuration page. You will need to supply an administrative password, included with your WAP’s documentation, to log in (see Figure 24-13). Setup screens vary from vendor to vendor and from model to model. Figure 24-14 shows the initial