Wireless Clients Networking in Ad Hoc Mode in C#

Drawing PDF 417 in C# Wireless Clients Networking in Ad Hoc Mode

Using Both Infrastructure Mode and Ad Hoc Mode Windows XP can operate in both wireless modes. Perhaps you use a wireless laptop at work in an office that uses infrastructure mode. Your laptop uses the office network during the day through a wireless access point. However, at night, you might bring your laptop home and want to connect your laptop to your home network for Internet access by connecting to a wireless-equipped desktop computer. Windows includes a service called Wireless Zero Configuration, which initiates a sequential process for determining the appropriate wireless network mode to use. Windows XP first searches for a wireless access point. If one is found, Windows XP switches the wireless adapter to infrastructure mode. If no access point is available, Windows XP looks for other computers operating in ad hoc mode. This process lets you move from infrastructure to ad hoc mode as needed without making any changes to the configuration of the wireless adapter. This feature requires that the software drivers for the wireless adapters support the Wireless Zero Configuration service.

To create a wireless network, you need wireless NICs for the computers that will participate on the wireless network as well as a wireless access point if you plan on configuring your wireless network to use infrastructure mode.

computers. PCI adapters are also available and allow you to plug a PC Card wireless NIC into a desktop computer. Some laptops also include built-in wireless NICs. Each wireless NIC has a miniature antenna for transmitting and receiving wireless data. Major networking companies like NetGear, Linksys, and SMC produce wireless networking devices in addition to their more traditional wired networking devices. Wireless NICs typically range in cost from $60 to $100; thus, they re a little more expensive than Ethernet NICs, but the price difference should not deter you from building a wireless network. Make sure that any wireless NIC you buy is compatible with the standard you intend to use, either 802.11b or 802.11a.

devices or can be built into other devices such as residential gateways. Some have built-in wireless NICs and antennas, whereas others provide a PCMCIA slot in which to insert a PC Card wireless network adapter. They also often include ports for adding more flexible external antennas.

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If you want to extend a wired LAN with the wireless network connection, you simply connect the wireless access point to the Ethernet network with an RJ-45 cable. Wireless clients can then communicate with one another through the wireless access point, and if the access point is also connected to a wired network hub, the clients can communicate with the wired network as well. Wireless access points tend to be more expensive than simple wired hubs, and as with hubs, there are many options to choose from.

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Topology refers to the physical layout of your network. Before purchasing any wireless networking equipment, you need to take a look at your needs and make a firm decision about how the wireless network will benefit you. How many computers will have wireless network adapters Do you need an access point Will you combine an existing network with wireless access, or do you want an entirely wireless network These are important questions to consider, and the following sections point out some topology options for you. Note that the following sections describe wireless networking in a home or small office setting because that is what you will most likely be configuring. In a large network environment, wireless networking takes more advanced planning and administrative planning, which is beyond the scope of this book.

In a completely wireless network, each computer can be outfitted with a wireless network adapter and configured in ad hoc mode. You do not need a wireless access point unless you are bridging two dissimilar networks, such as a wired Ethernet network and a wireless network. Ad hoc wireless networks are useful if you want to minimize the initial costs of bringing up a wireless network, if you don t need to connect to any outside networks, or if one of the ad hoc wireless hosts will also serve as an ICS host. In this latter configuration, the computer connected to the Internet acts as the ICS host, and the wireless clients access the Internet by connecting to the ICS host over the wireless network. With this configuration, ICS works the same way as it does in a wired network, as shown in the following illustration. You can learn more about setting up ICS in Using Internet Connection Sharing, page 301. Although ad hoc networks reduce the initial hardware cost of a wireless network, the limited range of each wireless card means that it s easy to disrupt network communications by moving computers too far apart from one another. This drastically limits the utility of ad hoc wireless networking in medium-to-large size network installations.