Extreme Networks Summit WM3000 Series Reference Manual page 185

RTS Threshold
Beacon Interval
DTIM Periods
Summit WM3000 Series Controller System Reference Guide
Request To Send
Specify a
WLAN's adopted Access Points.
RTS is a transmitting station's signal that requests a
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 sends
(without RTS/CTS) any data frames smaller than the threshold.
Consider the trade-offs when setting an appropriate RTS threshold for the
WLAN's Access Points. A lower RTS threshold causes more frequent RTS/
CTS exchanges. This consumes more bandwidth because of 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 thru 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.
Specify a beacon interval in units of 1,024 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 Points 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. The default is
100 K-us.
DTIM periods
Select the button to specify a period for
Indication Messages
(DTIM) for BSS IDs 1-4. This is a divisor of the
beacon interval (in milliseconds), for example, 10 : 100. (See "Beacon
Interval," above). A DTIM is periodically included in the beacon frame
transmitted from adopted Access Points. The DTIM period determines
how often the beacon contains a DTIM, for example, 1 DTIM for every 10
beacons. The DTIM indicates broadcast and multicast frames (buffered at
the Access Point) are soon to arrive. These are simple data frames that
require no acknowledgement, so nodes sometimes miss them. Increase
the DTIM/beacon settings (lengthening the time) to let nodes sleep longer
and preserve their battery life. Decrease these settings (shortening the
time) to support streaming-multicast audio and video applications that are
jitter-sensitive. The default DTIM period is 10 beacons for BSS 1-4.
(RTS) threshold (in bytes) for use by the
Clear To Send
Delivery Traffic
(CTS)
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