Netgear Router WGR614 User Manual

							Reference Manual for Cable/DSL Wireless Router WGR614 
Preparing Your Network C-21
 
Restarting the Network
Once you’ve set up your computers to work with the firewall, you must reset the network for the 
devices to be able to communicate correctly. Restart any computer that is connected to the firewall.
After configuring all of your computers for TCP/IP networking and restarting them, and 
connecting them to the local network of your WGR614 router, you are ready to access and 
configure the firewall. 
						

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C-22 Preparing Your Network
 
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							Wireless Networking Basics D-1
 
Appendix D
Wireless Networking Basics
This chapter provides an overview of Wireless networking.
Wireless Networking Overview
The WGR614 router conforms to the Institute of Electrical and Electronics Engineers (IEEE) 
802.11 standard for wireless LANs (WLANs) and a product update will bring the WGR614 into 
conformance to the 802.11g standard when it is ratified. 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 http://www.wi-fi.net), 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.  
						

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D-2 Wireless Networking Basics
 
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.
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. 
						

							Reference Manual for Cable/DSL Wireless Router WGR614 
Wireless Networking Basics D-3
 
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.
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 WGR614:
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.  
						

							Reference Manual for Cable/DSL Wireless Router WGR614 
D-4 Wireless Networking Basics
 
• 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 in below.
Figure 7-4:  Open system authentication
Shared Key Authentication
The following steps occur when two devices use Shared Key Authentication:
1.The station sends an authentication request to the access point.
2.The access point sends challenge text to the station.
3.The station uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and 
sends the encrypted text to the access point.
4.The access point decrypts the encrypted text using its configured WEP Key that corresponds 
to the station’s default key. The access point compares the decrypted text with the original 
challenge text. If the decrypted text matches the original challenge text, then the access point 
and the station share the same WEP Key and the access point authenticates the station. 
IN TER N ET LO CA LACT
12 3 4 5 678 LNK
LNK/ACT 10 0Cable/DSLProSafe Wireless VPN Security FirewallMODELFVM318PWR TESTWLANEnable
Access Point (AP) 1) Authentication request sent to AP
2) AP authenticates
3) Client connects to network
Open System
Authentication Steps
Cable or
DLS modem
Client
attempting
to connect 
						

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Wireless Networking Basics D-5
 
5.The station connects to the network.
If the decrypted text does not match the original challenge text (i.e., the access point and station do 
not share the same WEP Key), then the access point will refuse to authenticate the station and the 
station will be unable to communicate with either the 802.11 network or Ethernet network.
This process is illustrated in below.
Figure 7-5:  Shared key authentication
Overview of WEP Parameters
Before enabling WEP on an 802.11 network, you must first consider what type of encryption you 
require and the key size you want to use. Typically, there are three WEP Encryption options 
available for 802.11 products:
1. Do Not Use WEP: The 802.11 network does not encrypt data. For authentication purposes, the 
network uses Open System Authentication.
2. Use WEP for Encryption: A transmitting 802.11 device encrypts the data portion of every 
packet it sends using a configured WEP Key. The receiving device decrypts the data using the 
same WEP Key. For authentication purposes, the wireless network uses Open System 
Authentication.
IN TER N ET LO CA LACT
12 3 4 5 678 LNK
LNK/ACT 10 0Cable/DSLProSafe Wireless VPN Security FirewallMODELFVM318PWR TESTWLANEnable
Access Point 1) Authentication
request sent to AP
2) AP sends challenge text
3) Client encrypts
challenge text and
sends it back to AP
4) AP decrypts, and if correct,
authenticates client
5) Client connects to network
Shared Key
Authentication Steps
Cable or
DLS modem
Client
attempting
to connect 
						

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D-6 Wireless Networking Basics
 
3. Use WEP for Authentication and Encryption: A transmitting 802.11 device encrypts the data 
portion of every packet it sends using a configured WEP Key. The receiving 802.11 device 
decrypts the data using the same WEP Key. For authentication purposes, the 802.11 network uses 
Shared Key Authentication.
Note: Some 802.11 access points also support Use WEP for Authentication Only (Shared Key 
Authentication without data encryption). 
Key Size
The IEEE 802.11 standard supports two types of WEP encryption: 40-bit and 128-bit.
The 64-bit WEP data encryption method, allows for a five-character (40-bit) input. Additionally, 
24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key. (The 24 
factory-set bits are not user-configurable). This encryption key will be used to encrypt/decrypt all 
data transmitted via the wireless interface. Some vendors refer to the 64-bit WEP data encryption 
as 40-bit WEP data encryption since the user-configurable portion of the encryption key is 40 bits 
wide.
The 128-bit WEP data encryption method consists of 104 user-configurable bits. Similar to the 
forty-bit WEP data encryption method, the remaining 24 bits are factory set and not user 
configurable. Some vendors allow passphrases to be entered instead of the cryptic hexadecimal 
characters to ease encryption key entry.
128-bit encryption is stronger than 40-bit encryption, but 128-bit encryption may not be available 
outside of the United States due to U.S. export regulations.
When configured for 40-bit encryption, 802.11 products typically support up to four WEP Keys. 
Each 40-bit WEP Key is expressed as 5 sets of two hexadecimal digits (0-9 and A-F). For 
example, “12 34 56 78 90” is a 40-bit WEP Key.
When configured for 128-bit encryption, wireless products typically support four WEP Keys but 
some manufacturers support only one 128-bit key. The 128-bit WEP Key is expressed as 13 sets of 
two hexadecimal digits (0-9 and A-F). For example, “12 34 56 78 90 AB CD EF 12 34 56 78 90” 
is a 128-bit WEP Key.
Note: Typically, 802.11 access points can store up to four 128-bit WEP Keys but some 802.11 
client adapters can only store one. Therefore, make sure that your 802.11 access and client 
adapters configurations match. 
						

							Reference Manual for Cable/DSL Wireless Router WGR614 
Wireless Networking Basics D-7
 
WEP Configuration Options
The WEP settings must match on all 802.11 devices that are within the same wireless network as 
identified by the SSID. In general, if your mobile clients will roam between access points, then all 
of the 802.11 access points and all of the 802.11 client adapters on the network must have the same 
WEP settings. 
Note: Whatever keys you enter for an AP, you must also enter the same keys for the client adapter 
in the same order. In other words, WEP key 1 on the AP must match WEP key 1 on the client 
adapter, WEP key 2 on the AP must match WEP key 2 on the client adapter, etc.
Note: The AP and the client adapters can have different default WEP Keys as long as the keys are 
in the same order. In other words, the AP can use WEP key 2 as its default key to transmit while a 
client adapter can use WEP key 3 as its default key to transmit. The two devices will communicate 
as long as the AP’s WEP key 2 is the same as the client’s WEP key 2 and the AP’s WEP key 3 is 
the same as the client’s WEP key 3.
Wireless Channels
IEEE 802.11 wireless nodes communicate with each other using radio frequency signals in the 
ISM (Industrial, Scientific, and Medical) band between 2.4 GHz and 2.5 GHz. Neighboring 
channels are 5 MHz apart. However, due to spread spectrum effect of the signals, a node sending 
signals using a particular channel will utilize frequency spectrum 12.5 MHz above and below the 
center channel frequency. As a result, two separate wireless networks using neighboring channels 
(for example, channel 1 and channel 2) in the same general vicinity will interfere with each other. 
Applying two channels that allow the maximum channel separation will decrease the amount of 
channel crosstalk, and provide a noticeable performance increase over networks with minimal 
channel separation. 
						

							Reference Manual for Cable/DSL Wireless Router WGR614 
D-8 Wireless Networking Basics
 
The radio frequency channels used are listed in Ta b l e 7-1:
Note: The available channels supported by the wireless products in various countries are different.
The preferred channel separation between the channels in neighboring wireless networks is 25 
MHz (5 channels). This means that you can apply up to three different channels within your 
wireless network. There are only 11 usable wireless channels in the United States. It is 
recommended that you start using channel 1 and grow to use channel 6, and 11 when necessary, as 
these three channels do not overlap.
Table 7-1. 802.11 Radio Frequency Channels
Channel Center Frequency Frequency Spread
1 2412 MHz 2399.5 MHz - 2424.5 MHz
2 2417 MHz 2404.5 MHz - 2429.5 MHz
3 2422 MHz 2409.5 MHz - 2434.5 MHz
4 2427 MHz 2414.5 MHz - 2439.5 MHz
5 2432 MHz 2419.5 MHz - 2444.5 MHz
6 2437 MHz 2424.5 MHz - 2449.5 MHz
7 2442 MHz 2429.5 MHz - 2454.5 MHz
8 2447 MHz 2434.5 MHz - 2459.5 MHz
9 2452 MHz 2439.5 MHz - 2464.5 MHz
10 2457 MHz 2444.5 MHz - 2469.5 MHz
11 2462 MHz 2449.5 MHz - 2474.5 MHz
12 2467 MHz 2454.5 MHz - 2479.5 MHz
13 2472 MHz 2459.5 MHz - 2484.5 MHz