ExtremeIQ Cloud

About Channel Selection

This section allows you to make changes to the device channel width, DFS (Dynamic Frequency Selection), and DCS (Dynamic Channel Switching). The settings you can make here depend on the radio mode you selected in the Basic Parameters section.

Channel Selection Settings for 802.11b/n Radio Modes

Limit Channel Selection: Toggle on or off to limit channel selection to non-overlapping channels.

Region: Select the region in which the device is operating from the drop-down list.

Channel Model: The USA model is 3 channels, and the model for Europe is 4 channels.

Limit Channel Selection to: Enter the channels to which you want to limit selection. For example, default channels 1, 5, 9, and 13 for Europe, or 1, 6, and 11 for the US.

Configuring 802.11b/g and 802.11g/n 2.4 GHz Radio Settings

You can configure the following settings for the 802.11b/g and 802.11g/n radio modes:

Limit Channel Selection: Enable to limit channel selection for non-overlapping channels. Enabled by default. The 2.4 GHz radio has between 11 and 14 channels depending on the country code, but only three are completely non-overlapping (channels 1 - 6 - 11). Most wireless vendors recommend choosing one of the non-overlapping channels to avoid interference. However, in some cases, especially in very dense deployments, it can be better to use four channels, particularly in European countries where there are more channels available.

Region: Choose USA or Europe.

Channel Model: Choose 3 or 4 channels, depending on the region. The USA is limited to 3 channels. Europe can use either model.

Limit Channel Section to: Select the channels to which you want to limit channel selection. The default settings are as follows:

Required setting when USA and 3 channels are chosen: 1, 6, 11

Default setting when Europe and 3 channels are chosen: 1, 6, 11

Default setting when Europe and 4 channels are chosen: 1, 5, 9, 13

You can set the channel model as three or four channels depending on the selected region (USA or Europe). When you select Europe, you can modify the channel choices and set a different combination of channels.

If you disable the limiting of channel selection, the AP uses ACSP (Advanced Channel Selection Protocol) to determine the best among all available channels in its region using data about channel utilization, interference, CRC errors, noise floor, and the number of neighbors and their signal strength. The AP then selects the best channel available.

Configure 5 GHz (802.11a/n/ac) Radio Settings

The 5 GHz radio mode is 802.11a, 802.11a, or 802.11ac.

Channel Width: Select 20 MHz, 40 MHz, or 80 MHz. The default setting is 20 MHz (802.11b/g only).

More about Channel Width: One of the key features in the 802.11n and 802.11ac standards is channel bonding, in which the radio bonds two or four adjacent 20-MHz channels into one 40-MHz or 80-MHz channel to increase the transmit data bandwidth.

Unlike the 2.4 GHz radio band, the 5 GHz band has enough space for channel bonding. When you enable channel bonding on an AP whose region code is "FCC" and choose 40 MHz or 80 MHz ACSP (Advanced Channel Selection Protocol) automatically chooses the primary channel based on the current RF environment and optimizes channel usage.

You can also use channel bonding in the European Community in conjunction with DFS (Dynamic Frequency Selection), which makes channels 52-64 and 100-140 available in addition to channels non-DFS channels 36-48.

Without DFS enabled, channel bonding is not recommended for client access in the European Community because only the U-NII (Unlicensed National Information Infrastructure) lower band would be available (5.15-5.25 GHz; bandwidth: 100 MHz; channels 36 - 40 - 44 - 48) and there would not be enough space for three nonoverlapping 40-MHz channels.

The 5-GHz radio frequency spectrum is partitioned into the following U-NII bands:

U-NII Low: 5.15-5.25 GHz (bandwidth: 100 MHz; available in the U.S. and E.C.; supported by Extreme Networks devices)

U-NII Mid: 5.25-5.35 GHz (bandwidth: 100 MHz; available in the U.S. and E.C.)

U-NII Worldwide: 5.47-5.725 GHz (bandwidth: 255 MHz; available in the U.S. and E.C.)

U-NII Upper: 5.725-5.85 GHz (bandwidth: 125 MHz; available in the U.S.; supported by Extreme Networks devices)

Note

When a hive contains some APs that do not support channel bonding and others that do support it, the dynamic channel selection process works as follows:Channel selection for backhaul mode: The APs that support only 20-MHz channels converge on the control channel that the other members use as part of their 40-MHz channel.Channel selection for access mode: The APs that support only 20-MHz channels avoid choosing either the control channel or extension channel that the other members are using as part of their 40-MHz channels.

Disable UNII-3 Channels: Select On to disable the UNII-III band. This option is offered because some devices do not support the UNII-III band, and because enabling the band can create a problem with expected versus actual coverage. The default is Off.

Dynamic Frequency Selection: Enable DFS channel selection on APs as required for the regulatory region or country.

More about Dynamic Frequency Selection: Because radar systems use some bands in the 5 GHz spectrum, wireless devices operating in these bands must use DFS (Dynamic Frequency Selection) to detect radar activity and switch channels automatically to avoid interfering with radar operations. If an AP detects a radar signal while it is using one of the DFS channels, it automatically switches to a different channel and marks the first channel as unusable for 30 minutes. After 30 minutes, the first channel becomes available for use again. The AP might switch back to it later or simply continue using the new channel.

With DFS enabled, a 5 GHz radio to which you apply this radio profile can use the following channels:

ETSI: 36-48, 52-64, and 100–140

FCC: 36-48, 52-64, 100-116, 132-140, and 149-165

Channels 120, 124, and 128 are reserved for TDWR (Terminal Doppler Weather Radar) systems and are only available for wireless activity in the ETSI region when DFS is enabled; they are never available in the FCC region. When an AP chooses to use a DFS channel, it first performs a CAC (channel availability check) before it begins transmitting on the channel. The CAC wait time for the three weather-radar channels is 10 minutes. For all other DFS channels it is 1 minute.

Disable the DFS channel section and block the possible use of channels in the 52-64 and 100-140 ranges in the ETSI region and channels 52-64, 100-116, and 132-140 in the FCC region. The 5 GHz channels that do not require DFS are 36-48 for ETSI and FCC and 149-165 for FCC. These channels can always be used whether DFS is enabled or disabled. Note that channels 36-48 can only be used in the ETSI region when the AP is deployed indoors. If you disable DFS on APs deployed in the ETSI or FCC region, do not set a 5 GHz radio to use channels 52-64 and 100-140

Note

The DFS option becomes available only when the radio mode is 11a/n/ac, and it only takes effect when the AP is configured with the country code of a country complying with ETSI (European Telecommunications Standards Institute) or FCC (Federal Communications Commission) regulations. All Extreme Networks APs are certified to use DFS channels in the ETSI region and all are certified for the FCC region.

Because radar systems use some bands in the 5 GHz spectrum, wireless devices operating in these bands must use DFS (Dynamic Frequency Selection) to detect radar activity and switch channels automatically to avoid interfering with radar operations. If an AP detects a radar signal while it is using one of the DFS channels, it automatically switches to a different channel and marks the first channel as unusable for 30 minutes. After 30 minutes, the first channel becomes available for use again. The AP might switch back to it later or simply continue using the new channel.

With DFS enabled, a 5 GHz radio to which you apply this radio profile can use the following channels:

ETSI: 36-48, 52-64, and 100–140

FCC: 36-48, 52-64, 100-116, 132-140, and 149-165

Dynamic Channel Switching: Enable dynamic channel switching based on the following criteria:

Automatically select and switch channels during specified time interval: Select to enable automatic channel switching, and configure the time range and maximum client settings. Clear to disable this feature.

From and To: Set the time range when an AP re-evaluates its channel selection and can switch to a new radio channel each day.

Do not switch channels if the number of connected clients exceeds: Select to prevent the AP from switching channels based on the maximum number of connected clients (0-100).

Switch channels anytime if RF interference exceeds the threshold: Select to Enable or clear to Disable the automatic switching of channels based on the RF threshold and CRC errors:

Interference Threshold: Set the percentage level of RF interference that will trigger an AP to switch to another channel. Default is 25%. Range is 10 to 80%.

CRC Errors: Set the percentage of CRC errors on a channel which triggers an AP to switch to a different channel. Default is 25%. Range is 10 to 80%.

Do not switch channels if clients are connected: Select to allow the AP to stop switching channels when clients are connected. Clear to disable this feature.

More about Dynamic Channel Switching: (Available for both 2.4 GHz and 5 GHz radio profiles.) Enable dynamic channel switching using the following settings:

Use the automatically select and switch channels during specified time interval option for radio profiles that you intend to use in access mode with automatic channel selection enabled. You can configure when an AP automatically switches the transmission medium for a less busy and less noisy channel based on wireless activity statistics gathered during the day.

By default, this option is enabled, and the AP collects channel data throughout the day, and then re-evaluates its choice during a scheduled time slot. Based on its findings, the AP might switch to a different channel if it finds a better one and if the number of clients using the radio during the scheduled time are equal to or fewer than a specified number. Otherwise the AP continues using the same channel.

Note

This option does not apply to radios in backhaul mode.

From and To: This is the time range when an AP re-evaluates channel selection and can switch to a new radio channel on a daily basis. For example, if the settings are "From 02:00", "To 02:30", then at that time every day the AP re-evaluates its choice of channels based on data gathered throughout the day. If it discovers a better channel, it automatically switches as soon as the number of clients using the radio within that 30-minute window is the same as or fewer than the maximum. A good time to schedule this is when network activity is light, such as late at night.

Do not switch channels if the number of connected clients exceeds: This setting determines the maximum number of wireless clients that can be connected to the AP while it is permitted to switch channels. The number can be between 0 and 100. If the number of associated clients is equal to or fewer than this setting and if the AP finds a better channel, then it can switch to the new channel. Clients that are associated with the AP when the radio changes channels will lose their connections and will need to re-associate. If the number of clients exceeds the maximum setting, the AP refrains from switching to the new channel. Whenever a client deauthenticates during the scheduled time range, the AP checks if the number of clients still exceeds the maximum. If not, the AP switches channels. If the number of clients exceeds the maximum for the entire period during which the AP is allowed to change channels, then the AP does not change channels that day.

Switch channels anytime if RF interference exceeds the threshold: The protocol for automatically selecting channels, ACSP (Advanced Channel Selection Protocol), can counter RF interference in high density environments. You can choose to monitor the amount of RF interference, and number of CRC errors, and if either exceeds a specified threshold, the AP automatically switches to a clearer channel.

Interference Threshold: This is the level of RF interference that you find tolerable before an AP switches to another channel.

CRC Errors: This is the number of CRC errors that you consider acceptable on a channel before an AP switches to a different channel.

Do not switch channels if clients are connected: Clients that are connected while the AP switches channels might experience a momentary loss of connectivity when roaming to the same SSID on a different channel on the same AP, or on a neighboring AP. Consider the types of services that clients use on the WLAN when deciding to enable or disable this option. For applications that are not time sensitive, the brief break in connectivity typically passes unnoticed. For voice services, there might be a short—one second or less—pause on the line as the client transitions to another channel.

Optimize Radio Usage

Management frames such as beacons, probe requests and responses, and association requests and responses, consume airtime that might otherwise be used to transmit user data. Use the following settings to minimize management traffic by using higher data rates, and suppressing and reducing probe and association responses under certain circumstances.

High Density Configuration: APs are able to transmit beacons and management frames at the highest basic data rate that an SSID supports instead of the lowest basic rate, as is typically done. Using high data rates for management traffic frees up airtime and reduces the RF coverage area of a single radio, enabling the creation of more cells with varied frequencies throughout the entire area. The result in a high density environment is a greater number of RF cells and higher data rates for user traffic. Toggle ON and configure the following sections:

Data Rates to Support:

Choose High data rates to transmit management frames at the highest basic data rate specified in an SSID.

Choose Low data rates to use the lowest basic data rate.

Reduce Responses to Probe Requests:

Suppress successive requests within the same beacon interval: Select to enable APs to suppress responses to repeated probe requests from the same client received within a single beacon interval. Clear to disable.

Suppress response to broadcast probes by: Select to reduce responses to broadcast probe requests by allowing only one of several SSIDs to respond, which they do in rotation, or reduce responses from specific client device types. Clear to disable. This setting is disabled by default when high-density WLAN optimization is enabled. When this feature is enabled, select the suppression method:

Allowing only one SSID to respond at a time: Select to allow a single SSID to respond at a time.

Reducing responses to certain client device types: Select client device types to which the AP reduces its responses from the table. You can also select to add a new MAC OUI or choose other available object types by selecting .

Band Steering: (Available only when the radio mode is 802.11b/g or 802.11g/n.) Band steering enables the shift of clients from 2.4 to 5 GHz bands.

Note

Although this option is available only in the 2.4 GHz radio configuration, the appropriate settings are applied to both radios because the WiFi0 and WiFi1 interfaces operating as 2.4 GHz and 5 GHz radios work together with respect to band steering.

Band Steering Mode: The 5 GHz band has more available channels and sees lighter use than the 2.4 GHz band. By steering some clients with 5 GHz radio support to the 5 GHz band, APs can provide better throughput to 5 GHz clients and ease congestion in the 2.4 GHz band. APs suspend band steering when the number of clients associated with all hive neighbors on the 5-GHz radios reaches load limits. APs resume band steering when the 5 GHz radios are no longer overloaded.

From the drop-down list, choose how you want band steering to behave in your network. You can choose to balance, encourage, or enforce band steering.

Balanced band usage: Select to balance your wireless clients across both bands.

Allowed percentage distribution of 2.4 and 5.0 GHz clients: Use the slider to drag to, or select on, the percentage of the total number of clients that you want to occupy the 5 GHz band. For example, if you select 80%, then the APs place 80% of all clients onto the 5 GHz bands, leaving the remaining 20% of the clients on the 2.4 GHz band.

Encourage 5.0 GHz band usage: Select to give clients preferential treatment when migrating to the 5 GHz band, and not forcing 5 GHz band usage on all clients.

Enforce 5.0 GHz band usage: Select to disallow connections on the 2.4 GHz band.

Number of connection attempts from 2.4 GHz clients to ignore before responding: Configure APs to ignore the first several probe requests for each client that tries to connect. Enter a number between 1 and 100 for the number of initial probe requests you want the AP to ignore before it responds.

Client Load Balancing: Use airtime load balancing to have APs balance the wireless load according to the amount of airtime each client consumes, based on CRC error rates, or RF interference thresholds. Based on these conditions, overloaded APs can ignore probe and association requests from new clients, forcing them to associate with APs with more favorable conditions.

Enable client load balancing among neighboring hive members, as determined by the following selections:

Load balance clients based on:

Airtime: Choose this option to cause the APs to balance the wireless load according to the amount of airtime each client consumes by shifting clients that are using a lot of airtime to APs whose airtime load is relatively light.

CRC Error Rate: When the CRC error rate exceeds the maximum acceptable level for an AP radio, the AP will not accept probe and association requests from new clients. Set the threshold from 1 to 99%. The default is 30%. CRC errors indicate possible frame collisions caused by radio interference. If the CRC error rate exceeds the maximum acceptable level, which is 30% by default, then the AP does not accept any more probe and association requests from new clients. Enter a threshold from 1 to 99%.

RF Interference: When the amount of interference exceeds the maximum acceptable level, the AP will not accept probe and association requests from new clients. Set the threshold from 1 to 99%. The default is 40%.

Average Airtime Per Client: When the average amount of airtime that a client consumes in relation to all the available airtime is below a specified threshold, the AP will not accept probe and association requests from new clients. Set the threshold from 1 to 5%. The default is 4%.

Ignore probe and association requests from clients associated with other Extreme Networks devices until: APs use the following factors to determine whether to accept or ignore probe and association requests from clients:

Anchor Period Elapses: The anchor period is the time a client must remain anchored to an access point. Change the anchor period from 10 to 600 seconds (10 minutes). The default is 60 seconds. When an AP accepts a new client, it applies an anchor-and-release mechanism to ensure that the newly associated client does not disassociate from its current access point and roam to another one too soon. In a congested RF environment where all access points have similarly slow wireless links, a client might repeatedly roam in an attempt to improve its data rate. However, with all the access points in the same state, roaming might not offer any advantage, and can cause link instability for the client.

Note

An AP can release clients before the anchor period expires if the client's SNR drops below the SNR threshold or if the AP becomes overloaded.

Query neighbors about client load every: Set the query interval from 1 to 600 seconds (10 minutes). Default is 60 seconds.

Number of Clients: Select this option to cause the APs to balance the wireless load strictly according to the number of connected clients.

Ignore probe and association requests from clients associated with other Extreme devices until: APs use the following factors to determine whether to accept or ignore probe and association requests from clients:

Anchor Period Elapses: The anchor period is the time a client must remain anchored to an access point. Change the anchor period from 10 to 600 seconds (10 minutes). Default is 60 seconds.

Query neighbors about client load every: Set the interval from 1 to 600 seconds (10 minutes). Default is 60 seconds.

Note

An AP can release clients before the anchor period expires if the client's SNR drops below the SNR threshold or if the AP becomes overloaded.

Radio Load Balancing: Enable to distribute 5-GHz wireless clients evenly across the two radios when they are in dual-5G mode when an SSID is available on both radios.

Number of Connection Attempts: Enter between 1 and 10 connection attempts per client before the AP stops attempting to move the client to another 5-GHz radio. Default is 5 attempts.

Weak Signal Probe Request Suppression: Suppress probe responses if APs detect that the SNR (signal-to-noise ratio) for a client is weak, as measured against the SNR threshold.

Signal to Noise Threshold: An SNR of 10 dB or lower is generally considered poor and an SNR of 25 dB or greater is generally considered good. The default is 15 dB. Range is 1 to 100 dB.

Safety Net: Enable a period of time after which a device, when it is in an overloaded state or a client's SNR is weak, to respond to association requests. A longer safety net can result in longer delays during the initial WLAN connection but a greater chance of associating with an AP that can provide superior data rates. A shorter safety net can accelerate the initial connection, but might result in a less optimal data rate.

Safety Net Time Period: The default is 15 seconds. Set from 5-300 seconds (5 minutes).

Radio Settings

You can configure whether you want to use long or short preambles, adjust the beacon period (or interval), and enable the detection of spoofed BSSIDs.

When you enable short preambles, the AP broadcasts support of short preambles and attempts to negotiate using them with clients. If a client also supports short preambles, then the client and AP agree to use them. If a client only supports long preambles, then the AP automatically adjusts to accommodate it, and they agree to use long preambles instead.

When you select long preambles, the AP and client agree to use long preambles.

The IEEE 802.11b standard introduced a number of ways to improve performance. One way was to add a 56-bit "short" preamble to reduce frame header overhead and improve throughput. A short preamble adds a total of 96 microseconds to the transfer time, which significantly reduces the previous 144-bit "long" preamble which added a total of 192 microseconds to the transfer time.

Although a short preamble saves time and improves throughput, a long preamble allows more time for the receiver to tune in to and synchronize with the transmitting radio, providing additional decoding accuracy in noisier environments.

Preamble: (Available only when the radio mode is set to 11b/g or 11g/n)

Select Auto (Short/Long) to enable support for short preambles.

Select Long to disable short preamble support.

Beacon Period: Set the period during which APs send beacons. Access points broadcast beacons to clients within range. By default, APs send beacons every 100 TUs (that is, about 10 times per second). If APs are in an area with lots of background noise, you might want to add more time between beacon broadcasts, or set an interval from 40 to 3500 TUs (about 24 times per second to about once every 3.5 seconds).

Enable short guard interval: (802.11g/n, 802.11a, and 802.11ac only.) Select to enable a short guard interval of 400 nanoseconds. Clear to use the long guard interval of 800 nanoseconds. A guard interval is the amount of time between transmissions, ensuring that they do not collide. The 802.11 standard sets the guard interval at 800 nanoseconds, which is still suitable for large areas, such as warehouses or outdoors, where the distances between points of reflection are great. For smaller areas, such as office spaces, 802.11n allows the use of a shorter interval of 400 nanoseconds. Enabling this option in the right environment can improve data rates.

Enable Aggregate MAC Protocol Data Units: (802.11g/n, 802.11a, and 802.11ac only.): Aggregate MAC Protocol Data Unit (AMPDU) transmissions reduce overhead when the transmission channel is busy. Clear to disable. Enabled by default. Aggregate MAC Protocol Data Unit (AMPDU) transmissions reduce overhead when the transmission channel is busy. When AMPDU is enabled the AP combines data frames into fewer, larger frames before transmission and recognizes the format of larger frames when it receives them. Generally, enabling AMPDU increases performance.

Enable Frame Burst: (802.11g/n, 802.11a, and 802.11ac only.): Enable to allow a wireless client to transmit a burst sequence of up to three packets without releasing control of the transmission medium. Frame burst allows a wireless client to transmit data at a higher throughput by using the inter-frame wait intervals to burst a sequence of up to three packets without releasing control of the transmission medium.

Enable Very High Throughput (VHT) for 2.4 GHz radio band: (802.11g/n only): Enable to have the AP support VHT (very high throughput). VHT allows the AP to add new fields to the PPDU header to identify a VHT frame as opposed to an 802.11n or earlier high-throughput (HT) frame. The first three header fields can be read by legacy devices to allow coexistence.

Enable Transmit Beamforming: (802.11ac only.) Enable beamforming, signal processing that uses directional signal transmission to improve data transfer rates. Also select Mode: Auto or Explicit Only transmit beamforming. Beamforming uses directional signal transmission to improve data transfer rates. For the mode, select Select Auto or Explicit Only.

Enable MU-MIMO: (802.11ac and wifi1 radio only.) Enable multi-user multiple-input and multiple-output radio operation. MU-MIMO allows multiple users to receive data using different simultaneous spatial streams from an access point transmit radio chain.

Station Receive Chain: When MU-MIMO is enabled, select the receive radio chain Auto, chain 1 or chain 2 that the access point uses to receive data from the wireless client.

Note

Because MU-MIMO operation conflicts with smart antenna operation, disable smart antenna before enabling MU-MIMO.

Enable Smart Antenna: (802.11ac only, AP250 and AP550 only.) Enable or disable Extreme Networks smart antenna operation. Smart antenna operation allows AP250 and AP550 devices to use Extreme Networks RF IQ technology. Activating the smart antenna can dramatically improve transmit and receive performance.

Note

Because MU-MIMO operation conflicts with the smart antenna operation, when you enable smart antenna, ExtremeCloud IQ automatically disables MU-MIMO.

Configure Backhaul Failover

When you enable backhaul failover settings, the AP forms a mesh link with other hive members and can failover backhaul communications from eth0 to a wireless interface if the Ethernet link goes down.

Backhaul (or dynamic mesh) failover provides a way to overcome the failure of an Ethernet link in configurations where the radios are in dual or backhaul mode, and backhaul traffic flows over the Ethernet link. With backhaul failover enabled, if the Ethernet link becomes unresponsive, then radios that are in either dual mode or backhaul mode automatically negotiate with neighbor hive members to create a new mesh route, and then forward backhaul traffic over the mesh, thus bypassing the unresponsive link.

For example, to make use of all possible SSIDs, you can set both the WiFi0 and WiFi1 radios in dual mode and connect to the other hive members through the eth0 interface across the Ethernet network.

When you set both radios to operate in access mode backhaul failover is effectively disabled. An Ethernet failure triggers an AP to failover its default route from the Ethernet interface to a wireless interface that is already in either dual or backhaul mode.

Backhaul failover is enabled in the default radio profiles for the WiFi0 and WiFi1 radios, and the default for new profiles is Enabled.

Toggle ON and configure the following settings to define when to failover the backhaul link from Ethernet to wireless and when to return the backhaul to Ethernet:

Switch to Wireless Backhaul: Set how long the Ethernet link must be down to trigger a failover to the wireless link. Default is 2 seconds. Range is 1 to 5 seconds.

Revert Back to Wired Backhaul: Set how long the Ethernet link must be up before the AP returns backhaul communications to Ethernet. Default is 30 seconds. Range is 1 to 300 seconds.

Configure Miscellaneous Settings

Outdoor Deployment

You can configure outdoor APs to communicate wirelessly with each other across a great distance by using a directional antenna for the backhaul link while continuing to use omnidirectional antennas for access. However, you must make some adjustments to the radios to accommodate the longer transmission intervals. A Wi-Fi radio expects to receive an ACK for every transmitted unicast frame. If it does not receive an ACK, it retransmits the frame. If the distance between the transmitter and receiver is too great, the ACK timeout period elapses before the ACK from the receiver reaches the transmitter, causing the transmitter to retransmit frames repeatedly until concluding that the frames are not reaching their target. To counter this, define the range between the APs. By increasing the range, the radio increases the ACK timeout period accordingly.

Support radio up to: Set a distance (range) over which to support the radio. By increasing the range, the radio increases the ACK timeout period accordingly. Default is 300 meters. Range is 300 to 10,000 meters.

RF Interference Reports (802.11g/n, 802.11a and 802.11ac only):

Collect RF interference-related data from APs: Select to allow ExtremeCloud IQ to periodically poll APs and collect RF interface-related data. ExtremeCloud IQ informs APs to adopt a shorter polling interval if the following thresholds are exceeded.

Thresholds:

CRC Errors: Set the level of CRC errors for polling. Default threshold is 20% for 802.11g/n, and 35% for 802.11a and 802.11ac. Range is from 15 to 60%.

Channel Interference: Set the level of channel interference for polling. Default threshold is 20% for 802.11g/n, and 35% for 802.11a and 802.11ac. Range is from 15 to 60%.

Short term Average: Set the short-term average for polling. Default threshold is 5 minutes. Range is 5 to 30 minutes.

Client SLA Settings: To counter traffic congestion from clients with otherwise healthy Tx/Rx bit rates, APs can monitor client throughput and report SLA (service level agreements) status to ExtremeCloud IQ. APs can also dynamically increase the amount of airtime for backlogged clients to improve throughput.

SLA throughput levels can be High Density (performance-oriented), Normal Density (default), or Low Density (coverage-oriented). The level you select reflects the objectives of your deployment. For example, to provide coverage rather than throughput, select the normal- or low-density option. To provide high throughput, choose either the normal- or high-density options.

Note

Extreme Networks devices use airtime tokens created when dynamic airtime scheduling is enabled. Therefore, to apply SLA, be sure you first enable dynamic airtime in the network policy.

Select the throughput level for service level agreements:

High Density (performance-oriented)

Normal Density (default)

Low Density (coverage-oriented)

Configure SLA Levels

To see the default settings that constitute each throughput level, select Customize. For each radio mode (or phymode)—11a, 11b, 11g, 11n, 11ac—there are settings for bit rate, success rate, and usage.

In most cases, the AP and client use several different rates to transmit and receive packets, changing rates as factors such as RSSI and packet loss change. To determine a common "middle" point to which various client scores can be compared, ExtremeCloud IQ provides two settings for each phymode:

Rate: The rate setting defines the transmission bit rate that clients with healthy connectivity use. For 11a/b/g modes, the rates are in Mbps speed. For 11n mode, the rates are Mbps and MCS (modulation coding scheme). To modify the rate for a phymode, choose a rate from the drop-down list.

Success: The success setting defines the percentage of packets that you expect clients with healthy connectivity to transmit successfully(without retries) at the defined rate. To modify the success percentage for a phymode rate, enter a number from 1 to 100% in the Success field.

Usage: The usage setting defines the percent of time that clients with healthy connectivity will transmit at the defined rate. To modify the usage percentage, enter a number from 1 to 100% in the Usage field. Note that the aggregated usage for the two bit rates must be equal to or less than 100%.

After making modifications in the Customize SLA Definitions window, select Save.

To counter traffic congestion from clients with otherwise healthy Tx/Rx bit rates, APs can monitor client throughput and report SLA status to ExtremeCloud IQ. The APs can also dynamically increase the amount of airtime for clients with a significant backlog of queued packets so that the AP can send them out faster and improve throughput.

The following table shows the default settings for a normal-density network.


	High Density Network			High Density Network	High Density Network
Radio Mode	Rate	Success (1-100%)	Usage (1-100%)	Rate	Success (1-100%)	Usage (1-100%)	Rate	Success (1-100%)	Usage (1-100%)
11a	48 Mbps	70	50	36 Mbps	70	50	36 Mbps	60	50
	36 Mbps	80	50	24 Mbps	80	50	24 Mbps	70	50
11b	11 Mbps	70	50	11 Mbps	60	50	11 Mbps	50	50
	5.5 Mbps	80	50	5.5 Mbps	70	50	5.5 Mbps	60	50
11g	48 Mbps	70	50	36 Mbps	70	50	36 Mbps	60	50
	36 Mbps	80	50	24 Mbps	80	50	24 Mbps	70	50
11n	MCS 14	70	50	MCS 12	80	50	36 Mbps	60	50
	MCS 13	80	50	54 Mbps	70	50	24 Mbps	70	50
11ac	MCS 4/2	70	50	MCS 2/2	80	50	36 Mbps	60	50
	MCS 3/2	80	50	54 Mbps	70	50	24 Mbps	70	50

Configure WMM QoS Settings

Access Category: WMM classifies traffic into the following access categories—Voice, Video, Best-effort, and Background—and provides mechanisms to prioritize each category at differing levels.

Contention Window Minimum (1-15), Contention Window Maximum (1-15), and AIFS (1-15): These features work together to determine the back-off time for each category. The first two define the minimum and maximum contention window parameters. When there is contention for access to the wireless medium, the AP calculates a random value between these two parameters. The higher the values, the longer the AP will back off during periods of access contention, resulting in longer delays for that traffic category. The lower the values, the shorter the back-off period, with shorter the delays for traffic delivery. The AP adds the fixed AIFS (arbitration interframe space) back-off value to the first two values. The higher the setting, the longer the AP backs off, and the longer traffic is delayed during times of contention. The smaller the setting, the less time the AP backs off, resulting in shorter delays. The default values for the minimum contention window, maximum contention window, and AIFS are as follows for each access category:

Voice: (2 - 3) + 1

Video: (3 - 4) + 1

Best effort: (4 - 6) + 3

Background: (4 - 10) + 7

You can modify these values from 1 to 15 for the contention window parameters and from 1 to 15 for AIFS.

TXOP Limit (0-8192): The TXOP (transmission opportunity) limit parameter determines how long bursts of traffic last before relinquishing the medium. The default values for each access category are as follows, where each value divided by 32 indicates the total in microseconds:

Voice: 1504 (1504/32 = 47 microseconds)

Video: 3008 (3008/32 = 94 microseconds)

Best effort: 0

Background: 0

You can change these settings to values between 0 and 8192 (0 and 256 microseconds).

No ACK: This flag informs the recipient not to send ACKs of the frames it receives. This is useful for the video category where lost packets in streaming video go unnoticed and retransmissions are unnecessary. Select the check box to set the QosNoAck flag in the frame header.

Configure Sensor Mode Scan Settings

These settings determine how your APs behave during the scanning process. You can specify how long a device scans each channel and which channel are to be scanned.

Sensor Mode Scan Settings

Dwell Time: Dwell time defines how long the radio transmits on a specific channel frequency to scan client probe requests before moving to the next channel in the sequence. By default, the dwell time value is 1200 milliseconds (1.2 seconds). You can set the dwell time between 10 and 30000 milliseconds (30 seconds). For presence data collection, setting the dwell time above the default value raises the throughput of data collected on each channel. Setting the minimum dwell time below the default value reduces latency but also reduces the throughput of data collected on each channel.

Scan All Channels: Select to scan all radio channel numbers on APs in sensor mode on a per-radio basis to collect client probe request data. You can also clear the check box and then set individual channel numbers to be scanned.

Select Save.

Radio Profile Settings

Navigation

About Radio Profiles

Configure Radio Profile Basic Parameters

Configure Neighborhood Analysis (Background Scanning)

More about Background Scanning

About Channel Selection

Optimize Radio Usage