# Wi-Fi Multimedia Configuration

Wi-Fi™ Multimedia (WMM) is a quality of service enhancement that allows you to enhance the performance of your wireless network by adjusting the transmission priorities of audio, video, and voice applications to accommodate the different latency and throughput requirements of each application. By default, WMM is disabled.

WMM is based on Enhanced Distributed Channel Access (EDCA), as defined in 802.11e. For more information about WMM, see http://www.wi-fi.org.

You configure WMM to operate from each end of the connection: access point (ap) and station (sta).

- ap is the WMM configuration for the security device.

- station is the WMM configuration for the client. Clients internally queue traffic according to the four ACs and then send packets as they detect transmit opportunities granted by the controlling security device (ap). This configuration gets pushed to the clients when you click Activate Changes.

## Access Categories

Based on Internet Engineering Task Force (IETF) Differentiated Services Code Point (DSCP) headers, the security device and client sort traffic into one of four access categories (AC):

- Best effort (0)—traffic that cannot process QoS levels and traffic that is less sensitive to latency but that can be affected by long delays

- Background priority (1)—low priority traffic

- Video (2)—video traffic gets a higher priority than other data traffic

- Voice (3)—voice traffic gets the highest priority

The following table lists the mappings between access categories and Type of Service (TOS).

Access Category | TOS Value
Voice | 0xC0, 0xB8, 0xE0
Video | 0x80, 0xA0, 0x88
Best effort | 0x00, 0x60, or other
Background | 0x40, 0x20

Note: 802.1d tags are not supported.

## WMM Default Settings

The following terms describe the configurable WMM parameters used for access point (security device) and station (client) configuration:

- aifs: Arbitrary Inter-Frame Space Number (AIFSN) specifies the number of slots, after a SIFS duration, that the security device or client for an AC will check the medium-idle before transmitting or executing a backoff.

- Logcwmin and Logcwmax: WMM defines a Contention Window (CW), which is equivalent to a random backoff period. The CWmin parameter specifies the minimum number of slots of the contention window used by the security device or client for a particular AC to generate a random number for the backoff. If logcwmin is x, then CWmin is 2x-1. The CWmax parameter specifies the maximum number of slots of the window used by the security device or client for a particular AC to generate a random number for the backoff. If logcwmax is x, then CWmax is 2x-1.

Note: ScreenOS does not support contention-free or scheduled access.

- Txoplimit: Transmit Opportunity specifies the maximum amount of time the security device or client can initiate transmissions. If you set txoplimit to x, the maximum time is 32*x microseconds.

- Acm: Admission Control is an optional feature and is not currently supported.

- Ack Policy: You can enable or disable an acknowledgement policy for the access point. This parameter does not apply to clients.

## Configuring WMM

You can enable WMM on the 2.4 GHz (WLAN0) and/or 5GHz (WLAN1) transceivers. You configure WMM to operate from each end of the connection: access point (ap) and station (sta).

- ap is the WMM configuration for the security device.

- station is the WMM configuration for the client. Clients internally queue traffic according to the four ACs and then send packets as they detect transmit opportunities based on the parameters you set. This configuration is pushed to clients after you click Activate Changes.

1. Click Enable to enable WMM.

2. Enter values for the parameters for the access categories.

3. Click Apply to save changes to the wireless configuration, and then click Activate Changes to update the wireless configuration.

Note: When you click Activate Changes, the security device ends all wireless sessions abruptly. Wireless users must reconnect to continue service.