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Does the RTS threshold for 802.11 take into consideration the data packet plus the CRC that is appen

Does the RTS threshold for 802.11 take into consideration the data packet plus the CRC that is appended by the MAC or is it only the data packet?

During one of the tests I had set the RTS threshold to 1084 bytes. The packet received by the sniffer was 1088 bytes including the MAC header, data payload and the CRC. But still RTS/CTS transactions were not seen. When I increased the packet size by another two bytes RTS/CTS transactions were observed.

The IEEE standard also doesn't mention this explicitly. Could you please clarify? The same query is also valid for the Fragmentation threshold.

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According to the IEEE 802.11-1999 standard, RTS Threshold indicates "the number of octets in an MPDU below which an RTS/CTS handshake will not be performed." MPDU is the MAC Protocol Data Unit, which is the sequence of fields generated by the MAC sublayer for submission to the PHY layer for transmission over a physical interface. In other words, an MPDU does not include the PHY Preamble or Header, and it's the PHY Header that contains the CRC.

In addition, that standard says that "the length of the MPDU shall never be larger than the aFragmentationThreshold unless WEP is invoked [in which case} the MPDU shall be expanded by the IV [initialization vector] and ICV [integrity check value]... this may result in a fragment larger than the aFragmentationThreshold."

This was first published in February 2004

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