On Tue, Apr 5, 2016 at 1:00 PM, Grumbach, Emmanuel
<emmanuel.grumbach@xxxxxxxxx> wrote:
>>
>> Hello,
>>
>> I am trying to capture packets that are exchanged between an AP and a
>> smartphone on the 5Ghz frequency. For generating traffic, I upload UDP
>> traffic from a laptop PC towards the smartphone using iperf.
>>
>> The problem is that I can see _only_ the control frames like RTS/CTS, Block
>> ACK, while the data packets are not captured. I uploaded the Wireshark
>> capture files at [1] (located inside the folders whose name starts with 5Ghz).
>
> Most likely the packets on A band have a VHT preamble and your SKU is 11N only.
My card, Intel 7260 [1] supports 802.11 ac. So it should also support
VHT, right? Is there any interface in user-space for checking after
VHT?
However, I noticed a "failure" message in dmesg:
[ 4.030428] Intel(R) Wireless WiFi driver for Linux, in-tree:
[ 4.030570] iwlwifi 0000:04:00.0: irq 37 for MSI/MSI-X
[ 4.030760] iwlwifi 0000:04:00.0: Direct firmware load for
iwlwifi-7260-10.ucode failed with error -2
[ 4.035509] iwlwifi 0000:04:00.0: loaded firmware version
25.228.9.0 op_mode iwlmvm
[ 4.454772] iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band
Wireless N 7260, REV=0x144
[ 4.454825] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled
[ 4.455055] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled
[ 15.049933] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled
[ 15.050269] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled
Also, the maximum bit rate reported by iwconfig is 150 Mb/s, so my
assumption is that the card can't enter into the 802.11 ac mode, it
just stays into 802.11n.
doru@doru-N551JK:~$ iwconfig wlan0
wlan0 IEEE 802.11abgn ESSID:"5_mptcp"
Mode:Managed Frequency:5.24 GHz Access Point: C4:6E:1F:4B:10:A2
Bit Rate=150 Mb/s Tx-Power=22 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on
Link Quality=70/70 Signal level=-36 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:22 Missed beacon:0
[1] http://www.intel.com/content/www/us/en/wireless-products/dual-band-wireless-ac-7260-bluetooth-brief.html
> Another option is that the traffic uses LDPC encoding and this device doesn't support it.
>
>
>>
>> If I use the 2.4 frequency, all the frames are captured. I also uploaded the
>> Wireshark packet traces for 2.4Ghz at [1] (located inside the folders whose
>> name starts with 2.4 Ghz).
>>
>> Is this a known bug or am I doing something wrong?
>>
>> Additional details:
>> Wi-Fi card: iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band Wireless N 7260,
>> REV=0x144 Firmware version: iwlwifi 0000:04:00.0: loaded firmware version
>> 25.228.9.0 op_mode iwlmvm
>> Traffic encryption: WPA & WPA2 Personal
>> Setting up the card in wireless mode:
>> ip link set dev wlan0 down
>> iw wlan0 set type monitor
>> ip link set dev wlan0 up
>> iw wlan0 set freq 5240
>>
>> [1] https://drive.google.com/open?id=0B5SBH08PU_Chek9rOHY0VkxFRUE
>>
>> Thank you, Doru
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