|If you turn off a wireless radio,
the AP sends disassociation frames to all the wireless clients it is
supporting so that the wireless radio can be gracefully
shutdown and the clients can start the association process with other
defines the Physical Layer (PHY) standard the
wireless radio uses
The modes available on your AP depend on the country code setting.
|The range of available channels is
determined by the mode of the wireless radio interface and the country
code setting. If you select Auto
for the channel setting, and Auto
channel is configured, the AP scans available channels, immediately
selects a channel and begins operation. If interference or errors occur
on that channel, another channel is automatically selected.
The channel defines the portion of
the wireless radio spectrum the wireless radio uses for transmitting and
Each mode offers a number of channels, depending on how
the spectrum is licensed by national and transnational authorities such
as the Federal Communications Commission (FCC) or the International
Telecommunication Union (ITU-R).
|The 802.11n specification allows a
40-MHz-wide channel in addition to the legacy 20-MHz channel
available with other modes. The 40-MHz channel enables higher data
rates but leaves fewer channels available for use by other 2.4 GHz and 5
|This setting can be changed only
when the channel bandwidth is set to 40 MHz. A 40-MHz channel
considered to consist of two 20-MHz channels that are contiguous in the
frequency domain. These two 20-MHz channels are often referred to as the
Primary and Secondary channels. The Primary Channel is used for 802.11n
clients that support only a 20-MHz channel bandwidth and for legacy
the Primary Channel as the upper 20-MHz channel in the 40-MHz
the Primary Channel as the lower 20-MHz channel in the 40-MHz
|The guard interval is the dead
time, in nanoseconds, between OFDM symbols. The guard interval
prevents Inter-Symbol and Inter-Carrier Interference (ISI, ICI). The
802.11n mode allows for a reduction in this guard interval from the a
and g definition of 800 nanoseconds to 400 nanoseconds. Reducing the
guard interval can yield a 10% improvement in data throughput.
. The AP
transmits data using a 400 ns guard Interval when communicating
with clients that also support the short guard interval.
. The AP
transmits data using an 800 ns guard
|The protection feature contains
rules to guarantee that 802.11 transmissions do not cause
interference with legacy stations or applications. By default, these
protection mechanisms are enabled (Auto
). With protection enabled,
protection mechanisms will be invoked if legacy devices are within range
of the AP.
You can disable (Off
) these protection mechanisms;
however, when protection is off, legacy clients or APs within range can
be affected by 802.11n transmissions. Protection is also available when
the mode is 802.11b/g. When protection is enabled in this mode, it
protects 802.11b clients and APs from 802.11g transmissions.
This setting does not affect the ability
of the client to associate with the AP.
|Beacon frames are transmitted by
an AP at regular intervals to announce the existence of the
network. The default behavior is to send a beacon frame once every 100
milliseconds (or 10 per second).
|The Delivery Traffic Information
Map (DTIM) message is an element included in some Beacon
indicates which client stations, currently sleeping in low-power mode,
have data buffered on the AP awaiting pick-up.
|The fragmentation threshold is a
way of limiting the size of packets (frames) transmitted over the
network. If a packet exceeds the fragmentation threshold you set,
the fragmentation function is activated and the packet is sent as
multiple 802.11 frames.
Fragmentation involves more
overhead both because of the extra work of dividing up and
reassembling of frames it requires, and because it increases message
traffic on the network. However, fragmentation can help improve
network performance and reliability if
By default, fragmentation is off.
We recommend not using fragmentation unless you suspect wireless radio
interference. The additional headers applied to each fragment
increase the overhead on the network and can greatly reduce
|Changing the RTS threshold can
help control traffic flow through the AP, especially one with a lot of
clients. If you specify a low threshold value, RTS packets will be
sent more frequently. This will consume more bandwidth and reduce the
throughput of the packet. On the other hand, sending more RTS packets
can help the network recover from interference or collisions which might
occur on a busy network, or on a network experiencing electromagnetic
|The default value, which is
, can be more
cost-efficient than a lower level since it gives the AP a maximum
broadcast range and reduces the number of APs needed.
To increase capacity of the
network, place APs closer together and reduce the value of the transmit
power. This helps reduce overlap and interference among APs. A lower
transmit power setting can also keep your network more secure because
weaker wireless signals are less likely to propagate outside of the
physical location of your network.
|Select the multicast traffic
transmission rate you want the AP to support. When the Multicast Rate
is set to Auto
, then the
least supported basic rate of the AP is selected, which is 1 Mbps if the
default configuration is considered.
expressed in megabits per second.
indicates rates that the AP supports. You can check
multiple rates (click a check box to select or de-select a rate).
The AP will automatically choose the most efficient rate based on
factors like error rates and distance of client stations from the
indicates rates that the AP will advertise to the
network for the purposes of setting up communication with other
APs and client stations on the network. It is generally more
efficient to have an AP broadcast a subset of its supported rate
|By default the Multicast/Broadcast Rate Limiting
option is enabled.
When you disable Multicast/Broadcast Rate Limiting
, the following fields will be
|Enter the rate limit you want to
set for multicast and broadcast traffic. The limit should be greater
than 1; the max value is 100 packets per second (pps). Any traffic
that falls below this rate limit will always conform and be transmitted
to the appropriate destination.