MPDU and MSDU

来自维基百科

MAC protocol data unit orMPDU is a message (Protocol data unit) exchanged between MAC entities in a communication system based on the layeredOSI model.

In systems where the MPDU may be larger than theMAC service data unit (MSDU), the MPDU may include multiple MSDUs as a result ofpacket aggregation. In systems where the MPDU is smaller than the MSDU, then one MSDU may generate multiple MPDUs as a result ofpacket segmentation.

MAC service data unit orMSDU stands for MAC Service Data Unit.

The MSDU is theservice data unit that is received from the logical link control (LLC) sub-layer which lies above the medium access control (MAC) sub-layer in a protocol stack. The LLC and MAC sub-layers are collectively referred to as theDLL.

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MAC层数据实体在接收到MSDU后，将构造MPDU（MAC层协议数据单元），具体方法是在MSDU前加上帧头MHR，在MSDU后加上帧尾，即MPDU=MHR+MSDU+MFR

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通信百科：

MSDU - MAC Service Data Unit，MAC业务数据单元;　　
在无线网络安全中，MSDU经过添加完整性校验MIC、分帧、添加IV、加密、添加MAC头部后，成为MPDU（MAC Protocol Data Unit，MAC协议数据单元）.

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MSDU是MAC层服务数据单元，表示MAC层载荷；当MAC层协议数据单元(MPDU)被发送到物理层(PHY)时，它便成为了物理层服务数据单元(PSDU)。

下图也不知是那个网络的信标帧（zigbee），我只管MSDU和MPDU的关系

 

转自：http://blog.163.com/hair_communication/blog/static/2019891192012326268299/