Motorola WiNG 4.4, Справочное руководство

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4 - 132 WiNG 4.4 Switch System Reference Guide
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 (or nodes) 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.
In 802.11b/g mixed RTS/CTS happens automatically. There is no way to disable RTS/CTS
unless the network and all the devices used are 802.11g or 802.11a only. The proper co-
existence of 802.11b and 802.11g is ensured through RTS/CTS mechanism. On 802.11g
radios CTS-to-self is enabled irrespective of whether or not 11b rates are enabled or disabled.
When ERP Protection is ON, the 11bg radio will perform a CTS-to-self before it transmits the
frame.
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.