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Motorola Series Switch WS5100 User Manual

Page 145

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Network Setup

4-71

Short Preambles only

If using an 802.11bg radio, select this checkbox for the radio to transmit using a short
preamble. Short preambles improve throughput. However, some devices (SpectraLink
phones) require long preambles. This checkbox does not display if using an 802.11a radio.

RTS Threshold

Specify a Request To Send (RTS) threshold (in bytes) for use by the WLAN's adopted access
ports.

RTS is a transmitting station's signal that requests a Clear To Send (CTS) response from a
receiving station. This RTS/CTS procedure clears the air where many MUs are contending
for transmission time. Benefits include fewer data collisions and better communication with
nodes that are hard to find (or hidden) because of other active nodes in the transmission
path.

Control RTS/CTS by setting an RTS threshold. This setting initiates an RTS/CTS exchange for
data frames larger than the threshold, and simply sends (without RTS/CTS) any data frames
that are smaller than the threshold.

Consider the trade-offs when setting an appropriate RTS threshold for the WLAN's access
ports. A lower RTS threshold causes more frequent RTS/CTS exchanges. This consumes
more bandwidth because of the additional latency (RTS/CTS exchanges) before
transmissions can commence. A disadvantage is the reduction in data-frame throughput. An
advantage is quicker system recovery from electromagnetic interference and data collisions.
Environments with more wireless traffic and contention for transmission make the best use
of a lower RTS threshold.

A higher RTS threshold minimizes RTS/CTS exchanges, consuming less bandwidth for data
transmissions. A disadvantage is less help to nodes that encounter interference and
collisions. An advantage is faster data-frame throughput. Environments with less wireless
traffic and contention for transmission make the best use of a higher RTS threshold. Default
is 2346

Beacon Interval

Specify a beacon interval in units of 1,000 microseconds (K-us). This is a multiple of the DTIM
value, for example, 100: 10. (See "DTIM Period," below). A beacon is a packet broadcast by
the adopted access ports to keep the network synchronized. Included in a beacon is
information such as the WLAN service area, the radio-port address, the broadcast
destination addresses, a time stamp, and indicators about traffic and delivery such as a
DTIM. Increase the DTIM/beacon settings (lengthening the time) to let nodes sleep longer
and preserve battery life. Decrease these settings (shortening the time) to support
streaming-multicast audio and video applications that are jitter-sensitive. Default is 100 K-
us.