MAC service data units (WLAN) (MSDU)

The MAC Service Data Unit (MSDU) is a service data unit( SDU) of WLANs and Ethernet that the MAC layer receives from the Logical Link Control( LLC) sublayer above it.

In802.11a, 802 .11n and 802.11ac WLANs, the MSDU has a length between 0 bytes and 2,304 bytes, whereas in Ethernet it comprises 1,500 bytes, with a maximum frame length of 1,518 bytes. This contains the encapsulated data oflayers 3 to 7. This data is accepted by the media access procedure and can be transmitted to another MAC layer within the network. The MSDU is part of the MAC Protocol Data Unit( MPDU) and follows the Address Field.