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Appendix A: Troubleshooting
Frequently Asked Questions
Wireless-N Access Point with Power Over Ethernet
CSMA/CA plus Acknowledge protocol
Multi-Channel Roaming
Automatic Rate Selection
RTS/CTS feature
Fragmentation
Power Management
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 is Ad-hoc?
An Ad-hoc wireless LAN is a group of computers, each with a WLAN adapter, connected as an independent
wireless LAN. An Ad-hoc wireless LAN is applicable at a departmental scale for a branch or SOHO operation.
What is Infrastructure?
An integrated wireless and wired LAN is called an Infrastructure configuration. Infrastructure is applicable to
enterprise scale for wireless access to a central database, or wireless application for mobile workers.
What is roaming?
Roaming is the ability of a portable computer user to communicate continuously while 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 set to the same channel number as the Access Point of the 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.
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41
Appendix A: Troubleshooting
Frequently Asked Questions
Wireless-N Access Point with Power Over Ethernet
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 the 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).
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.
Would the information be intercepted while transmitting on air?
WLAN features two-fold protection in security. On the hardware side, as with Direct Sequence Spread Spectrum
technology, it has the inherent security feature of scrambling. On the software side, the WLAN series offers a
variety of wireless security methods to enhance security and access control. Users can set it up depending upon
their needs.
Can Linksys wireless products support file and printer sharing?
Linksys wireless products perform the same function as LAN products. Therefore, Linksys wireless products can
work with NetWare, Windows NT/2000, or other LAN operating systems to support printer or file sharing.
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Appendix A: Troubleshooting
Frequently Asked Questions
Wireless-N Access Point with Power Over Ethernet
What is WEP?
WEP is Wired Equivalent Privacy, a data privacy mechanism based on a 40-bit shared-key algorithm, as described
in the IEEE 802.11 standard.
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 on to the network, the MAC address of a device stays the same, making it a valuable identifier for
the network.
How do I avoid interference?
Using multiple Access Points on the same channel and in close proximity to one another will generate
interference. When employing multiple Access Points, make sure to operate each one on a different channel
(frequency).
How do I reset the Access Point?
Press the Reset button on the back of the Access Point for about ten seconds. This will reset the unit 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
an Access Point and wireless PC will create signal loss. Leaded glass, metal, concrete floors, water, and walls
will inhibit the signal and reduce range. Start with your Access Point 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. Also,
open the Access Point’s Web-based Utility. Click the
Wireless
tab and then the
Advanced Wireless
tab. Make
sure the Output Power is set to 100%.
Does the Access Point function as a firewall?
No. The Access Point is only a bridge from wired Ethernet to wireless clients.
I have excellent signal strength, but I cannot see my network.
Wireless security, such as WEP or WPA, is probably enabled on the Access Point, but not on your wireless adapter
(or vice versa). Verify that the same wireless security settings are being used on all devices in your wireless
network.
What is the maximum number of users the Access Point can handle?
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43
Appendix A: Troubleshooting
Frequently Asked Questions
Wireless-N Access Point with Power Over Ethernet
No more than 63, but this depends on the volume of data and may be fewer if many users create a large amount
of network traffic.
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44
Appendix B: Wireless Security
Security Precautions
Wireless-N Access Point with Power Over Ethernet
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 (as shown in this User Guide) (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 WPA if it is available. Please note that this may reduce
your network performance.
7.
Change the WEP encryption keys periodically.
To ensure network security, steps one through five should be followed, at least.
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.
Note:
Some of these security features are
available only through the network router or
access point. Refer to the router or access
point’s documentation for more information.

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