Brocade Communications Systems RFS6000 System Reference Manual page 200

4
Viewing access point information
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RTS Threshold
Specify a Request To Send (RTS) threshold (in bytes) for use by the WLAN's
adopted Access Points.
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 Clients
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.
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 1,024 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.
Self Healing Offset
When an Access Point increases its power to compensate for a failure, power is
increased to the country's regulatory maximum. Set the Self Healing Offset to
reduce the country's regulatory maximum power if Access Points are situated close
to each other or if an Access Point uses an external antenna.
DTIM Periods
Select the DTIM periods button to specify a period for Delivery Traffic 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.
Brocade Mobility RFS6000 and RFS7000 System Reference Guide
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