The 802.11 Reference Design and its documentation are under active development by the Mango team. The current release should be considered a beta- updates with bug fixes, API changes, new features and other refinements will be posted frequently. Please check the downloads page for the latest updates and post any questions about the design to the forums.

Ethernet Encapsulation and De-encapsulation

Ethernet encapsulation describes the process by which an 802.11 MPDU wraps a full Ethernet frame for transmission while Ethernet de-encapsulation describes the reverse. The 802.11-2012 standard describes this process in Annex P, "the Integration Function." The process is slightly different depending whether the device performing the action is an access point or station.

Access Point

AP Encapsulation and De-encapsulation

The above figure shows how an AP encapsulates and de-encapsulates different types of Ethernet frames.

Encapsulation

When an AP encapsulates a packet, it treats the destination address in that Ethernet frame as the receiver address (addr1) in the outgoing wireless MPDU. The source address of the Ethernet frame, however, is not the transmitter address (addr2) of the outgoing wireless MPDU -- the TA address must be the wireless MAC address (or BSSID) of the AP. Instead, the source address of the Ethernet frame is put into the third address location (addr3) of the outgoing 802.11 header.

De-encapsulation

De-encapsulation at the AP recognizes that a station must include the BSSID of the AP as the first argument of the 802.11 header. This receiver address (addr1) is not the destination address of the Ethernet frame. Instead, the destination address is included in the third address location (addr3) of the incoming 802.11 header. The transmitter address (addr2) is the source address of the Ethernet frame that should be generated.

Station

STA Encapsulation and De-encapsulation