Valter,
The L-SIG (legacy signaling) field is part of an .11 Preamble and the Preamble contains the transmission and vector information for the each transmitted frame. The L-SIG field itself contains a length and rate sub-field. It’s this rate sub-field that seems to be at issue. For 5GHz transmissions, the rate sub-field should always be set to 6Mbps and is represented by a 4-bit value (1101).
The problem, according to the error message, is that the rate value is being interpreted as being “0”...which is certainly not an existing data rate, right? And hence the error message.
As for actually capturing an example to see what is in the air, this is going to be a problem because as far as I know, the Preamble is not something that is decoded and presented by capture tools. The preamble is essentially information that is really only useful to the wireless hardware (I’ve never needed or wanted to look at actual Preamble information in a wireless capture before).
I’ve looked in Wireshark, using an adapter in monitor mode, and the most I’m seeing in the radio-tap header section under the ‘Present Flags’ is whether the L-SIG is absent or not. It doesn’t tell us what the ‘rate’ value is in the L-SIG sub-field in the frame’s Preamble. And w/o this, you cannot analyze a wireless capture to validate if a frame’s rate value is actually “0” or not.
This is going to be one of those issues where we need to let GTAC and engineering do what they do best.
