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User Manual for the NETGEAR WGE111 Wireless Game Adapter
Understanding IP Addresses
B-7
Address Resolution Protocol
An IP address alone cannot be used to deliver data from one device to another on a LAN. In order
for data to be sent from one device on the LAN to another, you must convert the IP address of the
destination device to its media access control (MAC) address. Each device on an Ethernet network
has a unique Ethernet MAC address, which is a 48-bit number assigned to each device by the
manufacturer. The technique that associates the IP address with a MAC address is known as
address resolution, and IP uses the Address Resolution Protocol (ARP) to do this.
If a device needs to send data to another station on the network and it does not already have the
destination MAC address recorded, ARP is used. An ARP request is broadcast onto the network,
and all stations receive and read the request. The destination IP address is included as part of the
message so that only the station with the correct IP address responds to the ARP request and all
other nodes discard it.
The node with the right IP address responds with its own MAC address directly to the sender,
providing the transmitting station with the destination MAC address needed for it to send the data.
The IP address data and MAC address data for each node are held in an ARP table, so that the next
time data needs to be sent, the address can be obtained from the address information in the table.
IP Configuration by DHCP
When an IP-based local area network is installed, each workstation must be configured with an IP
address. If the workstations need to access the Internet, they should also be configured with a
gateway address and one or more DNS server addresses. As an alternative to manual
configuration, there is a method by which each device on the network can obtain this configuration
information automatically. A device on the network may act as a Dynamic Host Configuration
Protocol (DHCP) server. The DHCP server stores a list or pool of IP addresses, along with other
information (such as gateway and DNS addresses) that it may assign to the other devices on the
network. The most of NETGEAR routers have the capacity to act as a DHCP server.
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User Manual for the NETGEAR WGE111 Wireless Game Adapter
B-8
Understanding IP Addresses
Page 63 / 88
Wireless Networking Basics
C-1
Appendix C
Wireless Networking Basics
This chapter provides an overview of wireless networking.
Wireless Networking Overview
On an 802.11b or g wireless link, data is encoded using direct-sequence spread-spectrum (DSSS)
technology and is transmitted in the unlicensed radio spectrum at 2.5GHz. The maximum data rate
for the wireless link is 11 Mbps, but it will automatically back down from 11 Mbps to 5.5, 2, and 1
Mbps when the radio signal is weak or when interference is detected. The 802.11g auto rate
sensing rates are 1, 2, 5.5, 6, 9, 12, 18, 24, 36, 48, and 54 Mbps.
The 802.11 standard is also called Wireless Ethernet or Wi-Fi by the Wireless Ethernet
Compatibility Alliance (WECA, see
), an industry standard group promoting
interoperability among 802.11 devices. The 802.11 standard offers two methods for configuring a
wireless network — ad hoc and infrastructure.
Infrastructure Mode
With a wireless access point, you can operate the wireless LAN in the infrastructure mode. This
mode provides wireless connectivity to multiple wireless network devices within a fixed range or
area of coverage, interacting with wireless nodes via an antenna.
In the infrastructure mode, the wireless access point converts airwave data into wired Ethernet
data, acting as a bridge between the wired LAN and wireless clients. Connecting multiple access
points via a wired Ethernet backbone can further extend the wireless network coverage. As a
mobile computing device moves out of the range of one access point, it moves into the range of
another. As a result, wireless clients can freely roam from one access point domain to another and
still maintain seamless network connection.
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User Manual for the NETGEAR WGE111 Wireless Game Adapter
C-2
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.
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User Manual for the NETGEAR WGE111 Wireless Game Adapter
Wireless Networking Basics
C-3
802.11 Authentication
The 802.11 standard defines several services that govern how two 802.11 devices communicate.
The following events must occur before an 802.11 Station can communicate with an Ethernet
network through an access point such as the one built in to the WGE111:
1.
Turn on the wireless station.
2.
The station listens for messages from any access points that are in range.
3.
The station finds a message from an access point that has a matching SSID.
4.
The station sends an authentication request to the access point.
5.
The access point authenticates the station.
6.
The station sends an association request to the access point.
7.
The access point associates with the station.
8.
The station can now communicate with the Ethernet network through the access point.
An access point must authenticate a station before the station can associate with the access point or
communicate with the network. The IEEE 802.11 standard defines two types of authentication:
Open System and Shared Key.
Open System Authentication
allows any device to join the network, assuming that the device
SSID matches the access point SSID. Alternatively, the device can use the “ANY” SSID
option to associate with any available access point within range, regardless of its SSID.
Shared Key Authentication
requires that the station and the access point have the same WEP
Key to authenticate. These two authentication procedures are described below.
Open System Authentication
The following steps occur when two devices use Open System Authentication:
1.
The station sends an authentication request to the access point.
2.
The access point authenticates the station.
3.
The station associates with the access point and joins the network.
This process is illustrated below.

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