ZyAIR G-220 User’s Guide
2-6
Wireless Station Mode Configuration
You should only configure
RTS/CTS Threshold
if the possibility of hidden nodes exists on your network
and the “cost” of resending large frames is more than the extra network overhead involved in the RTS
(Request To Send)/CTS (Clear to Send) handshake.
If the
RTS/CTS Threshold
value is greater than the
Fragmentation Threshold
value (see next), then the
RTS (Request To Send)/CTS (Clear to Send) handshake will never occur as data frames will be fragmented
before they reach
RTS/CTS Threshold
size.
Enabling the RTS Threshold causes redundant network overhead that could
negatively affect the throughput performance.
2.5 Authentication
Type
The IEEE 802.11b standard describes a simple authentication method between the wireless stations and
AP. Three authentication modes are defined: Auto, Open and Shared.
Open authentication mode is implemented for ease-of-use and when security is not an issue. The wireless
station and the AP do
not
share a secret key. Thus the wireless stations can associate with any AP and listen
to any data transmitted plaintext.
Shared authentication
mode involves a shared secret key to authenticate the wireless station to the AP. This
requires you to enable the WEP encryption and specify a WEP key on both the wireless station and the AP.
Auto authentication mode allows the ZyAIR to switch between the open and shared key authentication
modes automatically. Use the auto mode if you do not know the authentication mode of the other wireless
stations.
2.6 Preamble
Type
A preamble is used to synchronize the transmission timing in your wireless network. There are two
preamble modes:
Long Preamble
and
Short Preamble
.
Short preamble takes less time to process and minimizes overhead, so it should be used in a good wireless
network environment when all wireless stations support it.
Select
Long Preamble
if you have a ‘noisy’ network or are unsure of what preamble mode the access point
or the other wireless stations support as all IEEE 802.11b compliant wireless adapters must support long
preamble. However, not all wireless adapters support short preamble. Use long preamble if you are unsure
what preamble mode the wireless adapters support, to ensure interpretability between the ZyAIR and the
access point/wireless stations and to provide more reliable communication in ‘noisy’ networks.
Select
Auto
to have the ZyAIR automatically use short preamble when all access point/wireless stations
support it, otherwise the ZyAIR uses long preamble.
The ZyAIR and the access point/wireless stations MUST
use the same preamble mode in order to
communicate.
