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Advanced Settings
The advanced wireless settings directly control the behavior of the wireless radio device in the AP and its interaction with the physical medium; that is, how and what type of electromagnetic waves the AP emits.
Different settings display depending on the mode you select. The following table describes the fields and configuration options for the Advanced Settings page.
If you turn off a wireless radio, the AP sends disassociation frames to all the wireless clients it is currently supporting so that the wireless radio can be gracefully shutdown and the clients can start the association process with other available APs.
Note: If Status is set to Off, then all fields are not able to be edited.
The Mode defines the Physical Layer (PHY) standard the wireless radio uses
Note: The modes available on your AP depend on the country code setting.
Select the Channel.
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 receiving. 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 GHz devices.
This setting can be changed only when the channel bandwidth is set to 40 MHz. A 40-MHz channel can be 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 clients.
Upper. Set the Primary Channel as the upper 20-MHz channel in the 40-MHz band.
Lower. Set the Primary Channel as the lower 20-MHz channel in the 40-MHz band.
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.
Yes. The AP transmits data using a 400 ns guard Interval when communicating with clients that also support the short guard interval.
No. The AP transmits data using an 800 ns guard interval.
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.
Note: 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 wireless 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 frames. It indicates which client stations, currently sleeping in low-power mode, have data buffered on the AP awaiting pick-up.
The measurement is in beacons. For example, if you set this field to 1, clients will check for buffered data on the AP at every beacon. If you set this field to 10, clients will check on every 10th beacon.
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 properly configured.
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 throughput.
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 interference.
The default value, which is Full, 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.
Rate is expressed in megabits per second.
Supported 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 AP.
Basic 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 sets.
By default the Multicast/Broadcast Rate Limiting option is enabled. When you disable Multicast/Broadcast Rate Limiting, the following fields will be disabled.
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.
Setting a rate limit burst determines how much traffic bursts can be before all traffic exceeds the rate limit. This burst limit allows intermittent bursts of traffic on a network above the set rate limit.