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Appendix A: Troubleshooting
Frequently Asked Questions
Wireless-N Broadband Router
Can the Router act as my DHCP server?
Yes. The Router has DHCP server software built-in.
Can I run an application from a remote computer over the wireless network?
This will depend on whether or not the application is designed to be used over a network. Consult the
application’s documentation to determine if it supports operation over a network.
What is the IEEE 802.11g standard?
It is one of the IEEE standards for wireless networks. The 802.11g standard allows wireless networking hardware
from different manufacturers to communicate, provided that the hardware complies with the 802.11g standard.
The 802.11g standard states a maximum data transfer rate of 54Mbps and an operating frequency of 2.4GHz.
What is the IEEE 802.11b standard?
It is one of the IEEE standards for wireless networks. The 802.11b standard allows wireless networking hardware
from different manufacturers to communicate, provided that the hardware complies with the 802.11b standard.
The 802.11b standard states a maximum data transfer rate of 11Mbps and an operating frequency of 2.4GHz.
What IEEE 802.11g features are supported?
The product supports the following IEEE 802.11g functions:
CSMA/CA plus Acknowledge protocol
OFDM protocol
Multi-Channel Roaming
Automatic Rate Selection
RTS/CTS feature
Fragmentation
Power Management
What IEEE 802.11b features are supported?
The product supports the following IEEE 802.11b functions:
CSMA/CA plus Acknowledge protocol
Multi-Channel Roaming
Automatic Rate Selection
RTS/CTS feature
Fragmentation
Power Management
What is ad-hoc mode?
When a wireless network is set to ad-hoc mode, the wireless-equipped computers are configured to
communicate directly with each other. The ad-hoc network will not communicate with any wired network.
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Appendix A: Troubleshooting
Frequently Asked Questions
Wireless-N Broadband Router
What is infrastructure mode?
When a wireless network is set to infrastructure mode, the wireless network is configured to communicate with
a wired network through a wireless access point.
What is roaming?
Roaming is the ability of a portable computer to communicate continuously while the user and computer are
moving freely throughout an area greater than that covered by a single access point. Before using the roaming
function, the workstation must make sure that it is the same channel number with the access point of dedicated
coverage area.
To achieve true seamless connectivity, the wireless LAN must incorporate a number of different functions. Each
node and access point, for example, must always acknowledge receipt of each message. Each node must
maintain contact with the wireless network even when not actually transmitting data. Achieving these functions
simultaneously requires a dynamic RF networking technology that links access points and nodes. In such a
system, the user’s end node undertakes a search for the best possible access to the system. First, it evaluates
such factors as signal strength and quality, as well as the message load currently being carried by each access
point and the distance of each access point to the wired backbone. Based on that information, the node next
selects the right access point and registers its address. Communications between end node and host computer
can then be transmitted up and down the backbone.
As the user moves on, the end node’s RF transmitter regularly checks the system to determine whether it is in
touch with the original access point or whether it should seek a new one. When a node no longer receives
acknowledgment from its original access point, it undertakes a new search. Upon finding a new access point, it
then re-registers, and the communication process continues.
What is ISM band?
The FCC and their counterparts outside of the U.S. have set aside bandwidth for unlicensed use in the ISM
(Industrial, Scientific and Medical) band. Spectrum in the vicinity of 2.4 GHz, in particular, is being made available
worldwide. This presents a truly revolutionary opportunity to place convenient high-speed wireless capabilities in
the hands of users around the globe.
What is Spread Spectrum?
Spread Spectrum technology is a wideband radio frequency technique developed by the military for use in
reliable, secure, mission-critical communications systems. It is designed to trade off bandwidth efficiency for
reliability, integrity, and security. In other words, more bandwidth is consumed than in the case of narrowband
transmission, but the trade-off produces a signal that is, in effect, louder and thus easier to detect, provided that
the receiver knows the parameters of the spread-spectrum signal being broadcast. If a receiver is not tuned to
the right frequency, a spread-spectrum signal looks like background noise. There are two main alternatives,
Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS).
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Appendix A: Troubleshooting
Frequently Asked Questions
Wireless-N Broadband Router
What is DSSS? What is FHSS? And what are their differences?
Frequency-Hopping Spread-Spectrum (FHSS) uses a narrowband carrier that changes frequency in a pattern that
is known to both transmitter and receiver. Properly synchronized, the net effect is to maintain a single logical
channel. To an unintended receiver, FHSS appears to be short-duration impulse noise. Direct-Sequence Spread-
Spectrum (DSSS) generates a redundant bit pattern for each bit to be transmitted. This bit pattern is called a chip
(or chipping code). The longer the chip, the greater the probability that the original data can be recovered. Even if
one or more bits in the chip are damaged during transmission, statistical techniques embedded in the radio can
recover the original data without the need for retransmission. To an unintended receiver, DSSS appears as low
power wideband noise and is rejected (ignored) by most narrowband receivers.
What is a MAC Address?
The Media Access Control (MAC) address is a unique number assigned by the manufacturer to any Ethernet
networking device, such as a network adapter, that allows the network to identify it at the hardware level. For all
practical purposes, this number is usually permanent. Unlike IP addresses, which can change every time a
computer logs onto the network, the MAC address of a device stays the same, making it a valuable identifier for
the network.
How do I reset the Router?
Press the
Reset
button on the back panel for about five seconds. This will reset the Router to its default settings.
How do I resolve issues with signal loss?
There is no way to know the exact range of your wireless network without testing. Every obstacle placed between
the Router and a wireless PC will create signal loss.
Lead glass, metal, concrete floors, water and walls will
inhibit the signal and reduce range.
Start with the Router and your wireless PC in the same room and move it
away in small increments to determine the maximum range in your environment.
You may also try using different channels, as this may eliminate interference affecting only one channel.
I have excellent signal strength, but I cannot see my network.
Wireless security is probably enabled on the Router, but not on your wireless adapter (or vice versa).
Verify that
the same wireless security method and passphrase/keys are being used on all devices of your wireless network.
How many channels/frequencies are available with the Router?
There are eleven available channels, ranging from 1 to 11, in North America. There may be additional channels
available in other regions, subject to the regulations of your region and/or country.
If your questions are not addressed here, refer to the Linksys website, www.linksys.com.
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Appendix B: Wireless Security
Security Precautions
Wireless-N Broadband Router
Appendix B: Wireless Security
Linksys wants to make wireless networking as safe and easy for you as possible. The current generation of
Linksys products provide several network security features, but they require specific action on your part for
implementation. So, keep the following in mind whenever you are setting up or using your wireless network.
Security Precautions
The following is a complete list of security precautions to take (at least steps 1 through 5 should be followed):
1.
Change the default SSID.
2.
Disable SSID Broadcast.
3.
Change the default password for the Administrator account.
4.
Enable MAC Address Filtering.
5.
Change the SSID periodically.
6.
Use the highest encryption algorithm possible. Use PSK if it is available. Please note that this may reduce your
network performance.
7.
Change the WEP encryption keys periodically.
For information on implementing these security features, refer to “Chapter 5: Configuring the Wireless-N
Broadband Router.”
Security Threats Facing Wireless Networks
Wireless networks are easy to find. Hackers know that in order to join a wireless network, wireless networking
products first listen for “beacon messages”. These messages can be easily decrypted and contain much of the
network’s information, such as the network’s SSID (Service Set Identifier). Here are the steps you can take:
Change the administrator’s password regularly.
With every wireless networking device you use, keep in
mind that network settings (SSID, WEP keys, etc.) are stored in its firmware. Your network administrator is the
only person who can change network settings. If a hacker gets a hold of the administrator’s password, he, too,
can change those settings. So, make it harder for a hacker to get that information. Change the administrator’s
password regularly.
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Appendix B: Wireless Security
Security Threats Facing Wireless Networks
Wireless-N Broadband Router
SSID.
There are several things to keep in mind about the SSID:
1.
Disable Broadcast
2.
Make it unique
3.
Change it often
Most wireless networking devices will give you the option of broadcasting the SSID. While this option may be
more convenient, it allows anyone to log into your wireless network. This includes hackers. So, don’t broadcast
the SSID.
Wireless networking products come with a default SSID set by the factory. (The Linksys default SSID is “linksys”.)
Hackers know these defaults and can check these against your network. Change your SSID to something unique
and not something related to your company or the networking products you use.
Change your SSID regularly so that any hackers who have gained access to your wireless network will have to
start from the beginning in trying to break in.
MAC Addresses.
Enable MAC Address filtering. MAC Address filtering will allow you to provide access to only
those wireless nodes with certain MAC Addresses. This makes it harder for a hacker to access your network with
a random MAC Address.
WEP Encryption.
Wired Equivalent Privacy (WEP) is often looked upon as a cure-all for wireless security
concerns. This is overstating WEP’s ability. Again, this can only provide enough security to make a hacker’s job
more difficult.
There are several ways that WEP can be maximized:
1.
Use the highest level of encryption possible
2.
Use “Shared Key” authentication
3.
Change your WEP key regularly
PSK.
PSK is stronger than WEP encryption, and PSK2 has stronger encryption than PSK. PSK and PSK2 gives you
a choice of two encryption methods: TKIP (Temporal Key Integrity Protocol), which incorporates Message Integrity
Code (MIC) to provide protection against hackers, and AES (Advanced Encryption System), which utilizes a
symmetric 128-Bit block data encryption. (AES is stronger than TKIP.)
PSK-Enterprise and PSK2-Enterprise use a RADIUS (Remote Authentication Dial-In User Service) server for
authentication. RADIUS uses a RADIUS server and WEP encryption.
IMPORTANT:
Always remember that each device
in your wireless network MUST use the same
security method and key, or else your wireless
network will not function properly.

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