Q4 
If my computer is connected to a wireless
LAN, can it communicate with computers on
a wired LAN as well? |
|
To
do this you will need some sort of bridge
between the wireless and wired network. This
can be accomplished either with a hardware
access point or a software access point. Hardware
access points are available with various types
of network interfaces, such as Ethernet or
Token Ring, but typically require extra hardware
to be purchased if you networking requirements
change.
If networking requirements go beyond just
interconnecting a wired network to a small
wireless network, a software access point
may be the best solution.
A software access point does not limit the
type or number of network interfaces you use.
It may also allow considerable flexibility
in providing access to different network types,
such as different types of Ethernet, Wireless
and Token Ring networks. Such connections
are only limited by the number of slots or
interfaces in the computer used for this task.
Further to this the software access point
may include significant additional features
such as shared Internet access, web caching
or content filtering, providing significant
benefits to users and administrators. |
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| Q5
What is Direct-Sequence Spread Spectrum (DSSS)
Technology? |
|
| Direct-Sequence
Spread Spectrum. DSSS is one of two types
of spread spectrum radio, the other being
frequency-hopping spread spectrum. DSSS is
a transmission technology used in LAWN transmissions
where a data signal at the sending station
is combined with a higher data rate bit sequence,
or chipping code, that divides the user data
according to a spreading ratio. The chipping
code is a redundant bit pattern for each bit
that is transmitted, which increases the signal's
resistance to interference. If one or more
bits in the pattern are damaged during transmission,
the original data can be recovered due to
the redundancy of the transmission. |
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 |
|
| Q6 What
is Frequency-Hopping Spread Spectrum (FHSS)
Technology?/td> |
|
| Frequency-Hopping
Spread-Spectrum (FHSS) uses a narrowband carrier
that changes frequency in a pattern known
to both transmitter and receiver. Both sides
talk via "logical channel" for the
frequency hopping continuously. To maintain
a single logical channel both transmitter
and receiver should properly synchronized.
FHSS appears to be short-duration impulse
noise to an unintended receiver. |
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| Q7
What is Orthogonal Frequency Division Multiplexing
(OFDM) Technology? |
|
| Orthogonal
Frequency Division Multiplexing, an FDM modulation
technique for transmitting large amounts of
digital data over a radio wave. OFDM works
by splitting the radio signal into multiple
smaller sub-signals that are then transmitted
simultaneously at different frequencies to
the receiver. OFDM reduces the amount of crosstalk
in signal transmissions. 802.11a WLAN technology
uses OFDM. |
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| Q8
What is Complementary Code Keying (CCK) Technology?
|
|
Complementary
Code Keying, a set of 64 eight-bit code words
used to encode data for 5.5 and 11Mbps data
rates in the 2.4GHz band of 802.11b wireless
networking. The code words have unique mathematical
properties that allow them to be correctly
distinguished from one another by a receiver
even in the presence of substantial noise
and multipath interference.
CCK works only in conjunction with the DSSS
technology that is specified in the original
802.11 standard. It does not work with FHSS.
CCK applies sophisticated mathematical formulas
to the DSSS codes, permitting the codes to
represent a greater volume of information
per clock cycle. The transmitter can then
send multiple bits of information with each
DSSS code, enough to make possible the 11Mbps
of data rather than the 2Mbps in the original
standard. |
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|
| Q9
What are differences between Infrastructure
mode and Ad hoc mode? |
|
| The
802.11 standard defines two modes: infrastructure
mode and ad hoc mode. In infrastructure mode,
the wireless network consists of at least
one AP (access point) connected to the wired
network infrastructure and a set of wireless
end stations. The access point acts as the
base station for the wireless network, aggregating
access for multiple wireless stations onto
the wired network.
Ad hoc mode (also called peer-to-peer mode)
is simply a set of 802.11 wireless stations
that communicate directly with one another
without using an AP (access point) or any
connection to a wired network. This mode
is useful for quickly and easily setting
up a wireless network anywhere that a wireless
infrastructure does not exist or is not
required for services. |
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| Q10
What about security? |
|
| Wireless
communications obviously provide potential
security issues, as an intruder does not need
physical access to the traditional wired network
in order to gain access to data communications.
However, short wave receivers etc. This has
led to the common misconception that wireless
communications connot be eavesdropped at all.
However, eavesdropping is possible using special
equipment. To protect against any potential
security issues, 802.11 wireless communications
have a function called WEP ( Wired Equivalent
Privacy), a form of encryption which provides
privacy comparable to that of a traditional
wired network. If the wireless network has
information that should be secure then WEP
should be used, ensuring the data is protected
at traditional wired network levils. Also
it should be ntoed that traditional Virtual
Privated Networking (VPN) techniques will
work over wireless network in the same way
as traditional wired networks. |
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|
| Q11
Does wireless communications provide any security?
|
|
Wireless
communications obviously provide potential
security issues, as an intruder does not need
physical access to the traditional wired network
in order to gain access to data communications.
However, 802.11 wireless communications cannot
be received --much less decoded-- by simple
scanners, short wave receivers etc. This has
led to the common misconception that wireless
communications cannot be eavesdropped at all.
However, eavesdropping is possible using specialist
equipment.
To protect against any potential security
issues, 802.11 wireless communications have
a function called WEP (Wired Equivalent Privacy),
a form of encryption providing privacy comparable
to that of a traditional wired network. If
the wireless network has information that
should be secure then WEP should be used,
ensuring the data is protected at traditional
wired network levels.
Also it should be noted that traditional Virtual
Private Networking (VPN) techniques would
work over wireless networks in the same way
as traditional wired networks.
Section Two - Wireless Networking and the
Internet |
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| Q12
How can I use a wireless network to share
an Internet connection? |
|
| Once
you realize that wireless cards are analogous
to Ethernet cards and that empty space is
analogous to Ethernet cabling, the answer
to this question becomes clear. To share an
Internet connection across a LAN you need
two things:
(1) an Internet sharinig hardware device
or software program
(2) connection to a LAN
If your LAN is wireless, the same criteria
apply. You need a hardware or software access
point and a wireless LAN. Any computer equipped
with a wireless network card running suitable
Internet sharing software can be used as
a software access point. A number of vendors
offer hardware access points.
A hardware access point may provide Internet
Sharing capabilities to Wired LAN computers,
but does not usually provide much flexibility
beyond very simple configurations. |
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| Q13
What's difference between 64 bit WEP and 40
bit WEP? |
|
No
difference. 64 bit WEP is the same as 40 bit
WEP. The lower level of WEP encryption uses a
40 bit (10 Hex character) ¡§secret key¡¨ (set
by the user), and a 24 bit ¡§Initialization
Vector¡¨ (not under user control). Some
vendors refer to this level of WEP as 40 bit,
others as 64 bit. Either
way, they¡¦re the same encryption level and
can interoperate. |
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|
| Q14
Will 128-bit WEP communicate with 64-bit WEP?
|
|
No.
128-bit WEP will not communicate with 64-bit
WEP. Although 128 bit WEP also uses a 24
bit Initialization Vector, but it uses a 104
bit as secret key. Users need to use the same
encryption level in order to make |
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| Q15
What is Access Point? |
|
| A Wireless
LAN transceiver acts as a center point and
bridges between wireless and wired networks.
|
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| Q16
Does the Access Point function as a firewall?
|
|
| No.
The Access Point is only a bridge from wired
Ethernet to wireless clients. |
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| Q17
What is the maximum number of users the Access
Point facilitates? |
|
| It depends on the
volume of data and may be less if many users
create a large amount of network traffic.
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| Q18
What is Roaming? |
|
| As wireless
station move from the coverage area of one
AP to that of another, roaming mechanism allows
the connection to be handed off to new AP. |
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| Q19
What is UPnP (Universal Plug and Play)? |
|
| It
is designed to support zero-configuration,
"invisible" networking, and automatic
discovery for a breadth of device categories
from a wide range of vendors.
The UPnP Forum was formed in October 1999
to help define interconnectivity standards
to simplify the networking of intelligent
devices. Visit www.upnp.org for more information. |
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| Q20
What
is NAT ? |
|
Short
for Network Address Translation, an Internet
standard that enables a local-area network
(LAN) to use one set of IP addresses for internal
traffic and a second set of addresses for
external traffic. A NAT box located where
the LAN meets the Internet makes all necessary
IP address translations.
NAT serves main purposes:
1). Provides a type of firewall by hiding
internal IP addresses
2). Enables a company to use more internal
IP addresses. Since they're used internally
only, there's no possibility of conflict with
IP addresses used by other companies and organizations.
It is proposed and described in RFC-1631 and
is originally for solving the IP address depletion
problem. Basically, "each NAT box has
a table consisting of pairs of local IP addresses
and globally unique addresses," by which
the box can "translate" the local
IP addresses to global address and vice versa.
More Information:
RFC-1631: The IP Network Address Translator
(NAT)
http://www.faqs.org/rfcs/rfc1631.html |
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|
| Q21 What
is Auto-negotiation? |
|
| Auto-negotiation
is a technology standard defined by IEEE802.3u.
According to this standard, auto-negotiation
in a 100Base-T working group is a mechanism
that takes control of the cable when a connection
is established to a network device. Auto-negotiation
detects the various modes that exist in the
device on the other end of the wire and advertises
its own abilities to automatically configure
the highest performance mode of interoperation. |
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|
| Q22 What
is DHCP? |
|
| Short
for Dynamic Host Configuration Protocol, a
protocol for assigning dynamic IP addresses
to devices on a network. With dynamic addressing,
a device can have a different IP address every
time it connects to the network. In some systems,
the device's IP address can even change while
it is still connected. DHCP also supports
a mix of static and dynamic IP addresses. |
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| Q23
What is Maximum Transmission Unit (MTU) Size? |
|
Maximum
Transmission Unit (MTU) indicates the network
stack of any packet is larger than this value
will be fragmented before the transmission.
During the PPP negotiation, the peer of the
PPP connection will indicate its MRU and will
be accepted. The actual MTU of the PPP connection
will be set to the smaller one of MTU and
the peer¡¦s MRU.
The default is value 1400. |
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| Q24
What
is Clone MAC Address? |
|
Clone
MAC address is designed for your special application
that request the clients to register to a
server machine with one identified MAC address.
Since that all the clients will communicate
outside world through the WLAN Broadband Router,
so have the cloned MAC address set on the
WLAN Broadband Router will solve the issue. |
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| Q25
What is DDNS? |
|
| DDNS
is the abbreviation of Dynamic Domain Name
Server. It is designed for user own the DNS
server with dynamic WAN IP address. |
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| Q26
What
is NTP Client? |
|
| NTP
client is designed for fetching the current
timestamp from internet via Network Time protocol.
User can specify time zone, NTP server IP
address. |
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| Q27
What
is VPN? |
|
| VPN
is the abbreviation of Virtual Private Network.
It is designed for creating point-to point
private link via shared or public network |
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| Q28
What
is IP SEC? |
|
| IPSEC
is the abbreviation of IP Security. It is
used to transferring data securely under VPN. |
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