On 08/23/2015 05:15 PM, Gucea Doru wrote:
Hello, community
As you are using bcmdhd I don't think this particular community cares a
lot about it. But I will take the bait ;-)
I'm a Master student doing my research on a subject related to Android
and multiple paths between two nodes. What I try to do now is to allow
a client to connect to multiple APs (Access Points).
I started with the simplest use-case where I have only two APs (AP1
and AP2) and an Android client - a Nexus 5 device running the Kernel
from [1]. For the connection with AP1 I used the already present
interface wlan0. For the connection with AP2 I tried to use a newly
created virtual interface but the wpa_supplicant connection is not
successful. I'm not sure if this is a driver limitation or a driver
bug.
I am not sure either. For the upstream brcmfmac we don't allow it at the
moment. I am kinda surprised you were able to create the additional
interface. There are a couple of things that I can think of here which
may cause issues:
- APs operating on different channels.
- Both STA interfaces have powersave enabled.
- Firmware/driver do not support multi STA.
If APs are operating on the same channel it may work, but you probably
won't have advantage of MP-TCP because of medium use.
Regards,
Arend
I will detail what I've done. After killing the wpa_supplicant process
I followed the steps:
--- Created a virtual interface in the station mode ---
root@hammerhead:/ # iw phy phy0 interface add vif_AP2 type station
root@hammerhead:/ # ip link set dev vif_AP2 address 64:89:9a:81:0f:22
root@hammerhead:/ # ip link set dev vif_AP2 up
---- Connection to AP1 - SUCCESS ----
root@hammerhead:/data # wpa_supplicant -iwlan0 -c/data/tmp/preshared_key_AP1
The dmesg log from [2] proved that the connection was successful.
---- Connection to AP2 - FAILED ----
root@hammerhead:/ # wpa_supplicant -ivif_AP2 -c/data/tmp/preshared_key_AP2
The dmesg log from [3] proved that the connection failed.
It seems that the connection error is due to a failed PNO setup [3].
Also, the failed PNO setup seems to prevent the AP scanning process
from running. More accurate, what is this PNO setup? I looked into the
Kernel code [4] but I can't figure it out how I could avoid this
error.
PNO is preferred network offload in which firmware is configured with a
number of ssids and it will notify host when it finds one of those.
wpa_supplicant will do a couple of regular scans after which it requests
a scheduled_scan which the driver will use to configure PNO in firmware.
Looking at the log in [3] I get the impression this multi-STA thing is
not working at all. The regular scans don't find any AP, which is
already suspect. The PNO setup is rejected by the driver, because the
other interface is already connected to AP1.
Regards,
Arend
[1] https://github.com/gdetal/mptcp_nexus5
[2] https://drive.google.com/file/d/0B5SBH08PU_ChYzNIV3VxUWlqWGs/view?usp=sharing
[3] https://drive.google.com/file/d/0B5SBH08PU_ChNHdOck5UbjNERjQ/view?usp=sharing
[4] https://github.com/gdetal/mptcp_nexus5/blob/master/drivers/net/wireless/bcmdhd/dhd_pno.c
Any help is greatly appreciated,
Doru
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