802.11 Frame Control Fields

Version:

Indicates 802.11 version number (0)

Type:

These two bits indicate frame type: management, control, or data. Management frames are used for communication between stations and APs such as association, disassociation, probing, and beaconing. Control frames are used to provide reliable frame delivery service.

Subtype:

Depending on the type of field, subtype further identifies the function of a frame

To DS:

This field is set to 1 if the frame is destined to a DS from a station or an AP to another AP

From DS:

This field is set to 1 if the frame is leaving from a DS for a station or an AP. This field is set when a frame is sent from an AP

MF:

Indicates that more fragments follow the current one

Retry:

Indicates that this frame is a retransmission of a previous one that does not have an ACK

Power control:

This field is set to 1 if the transmission station is in sleep mode; it is set to 0 if it is in active mode

More data:

Indicates that the transmitter has more data for the intended receiver. If the transmitter is an AP, the field informs a station in sleep mode that more data are buffered at the AP

WEP:

This field is set to 1 to indicate that the frame body is encrypted using the WEP algorithm

Order:

This field is set to 1 to inform the receiver that a number of frames are in strict order