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OPERATIONAL DEFECT DATABASE
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AIR-ANT2524V4C-RS= self-identifying antennas do not identify themselves properly - they show as an invalid PID. The software assumes a gain of 6dBi, and so caps the transmit power accordingly (even though the actual gain is 2dBi in 2.4 GHz and 4 dBi in 5GHz.) With 8.10/pre-17.10 software installed, the access point may be in a crash loop, showing console messages such as: misc sia: Failed to get good reading [ ... ] NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [ ... ] CPU: 1 PID: 3611 Comm: insmod Tainted: P O 4.1.52 #5 Hardware name: Broadcom-v8A (DT) task: ffffffc0744ede00 ti: ffffffc027374000 task.ti: ffffffc027374000 PC is at sia_touch_bit+0x174/0x190 [sia_driver] LR is at sia_touch_bit+0x124/0x190 [sia_driver] [ ... ] Rebooting in 5 seconds.. The PC/LR values may vary, but will be in [sia_driver]. If the AP boots successfully, "show controllers dot11radio 0[/1] antenna" will show that the AP does not correctly recognize the antenna, and does not set the correct gain: Antenna: RX [ a b c d ] TX [ a b c d ] External Antenna Gain: 1. 6dBi 2. 6dBi 3. 6dBi 4. 6dBi SIA RPTNC: Present: 1, Gain: 170 SIA PID: C-ANT-DART-RPTNC SIA Description: RPTNC SIA DART SIA DART : Present: 0, Gain: 255 SIA PID: C-ANT-DART-RPTNC SIA Description: RPTNC SIA DART With AireOS 8.10, the WLC will recognize the antenna as SIA, but with an uneditable gain of "84 x 0.5 dBi". This causes reconfiguring the radio to fail with an "Antenna Gain : 84 : is an invalid value. Valid range is 0 40" error.
Seen with AIR-ANT2524V4C-RS= antennas (specific units) when cabled to an SIA capable access point, one of the following models: C9120AXE, C9130AXE
For an affected AIR-ANT2524V4C-RS= antenna cabled to an SIA-capable AP, a partial workaround is to attach the violet-banded antenna cable to any one of the orange-banded RP-TNC terminals (i.e. to terminal B, C or D), but NOT to the violet-banded terminal A. This will prevent the antenna from self-identifying, and so will allow configuring the antennas for their actual gain (i.e. 2 dBi in 2.4 GHz and 4 dBi in 5 GHz.) For full SIA functionality, the affected AIR-ANT2524V4C-RS= must be repaired or replaced.
This is a known manufacturing problem with specific AIR-ANT2524V4C-RS= antenna units. To validate whether your antennas have this problem, open a TAC case and provide the antenna serial numbers. TAC can assist with repairing the defective antennas. The crashing problem triggered by these antennas is fixed via CSCwb91041 in 17.10.1 and above.