Seen in Wireless DS (mesh, repeater, …) where an AP sends a frame to another AP, it is exiting the DS and destined to the DS at the same time in that situation. Only frame using all four addresses fields. It is also the case for all management and control frames (directly sent to the AP and not the DS)Ī frame sent by a station for an AP (destined to the DS) For values, please refer the to chunk “frame types”.ġ.4 and 1.5 To DS and From DS: The following table show the meaning of these fields combinations.Ī frame sent between two stations not being APs in a BSS or IBSS. The type indicates whether the frame is control, management or data and the subtype defines the frame more precisely. It will be incremented whenever a new revision of the standard comes out and shows fundamental incompatibility with previous versions.ġ.2 and 1.3 Type and Subtype fields: Type is 2 bit long and Subtype is 4 bits long. Here is the frame control field detailed:ġ.1 Protocol version field: 2 bits field that is currently set to 0 in 2007 revision of the standard. We will show what the frame control field contains and then explain the addresses fields.
QoS null is the QoS version of the null frame QoS data is the QoS version of the data frame Null frame is a frame meant to contain no data but flag information Data frame is the basic frame containing data ACK is the acknowledge frame sent to confirm receipt of a frame. CTS is the clear-to-send frame (often response to RTS) PS-Poll is the Power-save poll frame polling for buffered frames after a wake-up from a station Action is a frame meant for sending information elements to other stations (when sending in a beacon is not possible/best) Deauthentication is the frame terminating the authentication of a station. Authentication is the frame used to perform the 802.11 authentication (and not any other type of authentication) Disassociation is sent to terminate the association of a station
ATIM is the traffic indication map for IBSS (in a BSS, the TIM is included in the beacon) Beacon is a periodic frame sent by the AP (or stations in case of IBSS) and giving information about the BSS Probe response is sent by each BSS participating to that SSID Probe request is sent by a station in order to “scan” for an SSID Reassociation response is the response to the reassociation request Reassociation request is sent by a station changing association to another AP in the same ESS (so roaming between APs, or reassociating with the same AP)
Association response is sent in response to an association request Association request is sent by a station to associate to a BSS. All lines in italic and smaller caracters refer to Contention-Free systems and are never implemented in 99% of the wireless devices, so of little importance.
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