Netgear WG121 ユーザーズマニュアル

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User Manual for the NETGEAR 54 Mbps Wireless USB 2.0 Adapter WG121
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Wireless Networking Basics
 
Ad Hoc Mode (Peer-to-Peer Workgroup)
In an ad hoc network, computers are brought together as needed; thus, there is no structure or fixed 
points to the network - each node can generally communicate with any other node. There is no 
Access Point involved in this configuration. This mode enables you to quickly set up a small 
wireless workgroup and allows workgroup members to exchange data or share printers as 
supported by Microsoft networking in the various Windows operating systems. Some vendors also 
refer to ad hoc networking as peer-to-peer group networking.
In this configuration, network packets are directly sent and received by the intended transmitting 
and receiving stations. As long as the stations are within range of one another, this is the easiest 
and least expensive way to set up a wireless network. 
Network Name: Extended Service Set Identification (ESSID)
The Extended Service Set Identification (ESSID) is one of two types of Service Set Identification 
(SSID). In an ad hoc wireless network with no access points, the Basic Service Set Identification 
(BSSID) is used. In an infrastructure wireless network that includes an access point, the ESSID is 
used, but may still be referred to as SSID.
An SSID is a thirty-two character (maximum) alphanumeric key identifying the name of the 
wireless local area network. Some vendors refer to the SSID as network name. For the wireless 
devices in a network to communicate with each other, all devices must be configured with the 
same SSID.
Authentication and WEP
The absence of a physical connection between nodes makes the wireless links vulnerable to 
eavesdropping and information theft. To provide a certain level of security, the IEEE 802.11 
standard has defined two types of authentication methods, Open System and Shared Key. With 
Open System authentication, a wireless PC can join any network and receive any messages that are 
not encrypted. With Shared Key authentication, only those PCs that possess the correct 
authentication key can join the network. By default, IEEE 802.11 wireless devices operate in an 
Open System network. 
Wired Equivalent Privacy (WEP) data encryption is used when the wireless devices are configured 
to operate in Shared Key authentication mode. There are two shared key methods implemented in 
most commercially available products, 64-bit and 128-bit WEP data encryption.