Multi connection of BLE 6LoWPAN Border Router

[michael lee]

Hi

I had used one nRF52 Kit(nRF52832+nRF5_SDK_14.2.0) to connect  a BLE 6LoWPAN Border Router(Raspberry Pi 3B+Raspbian)

according to the IoT User Guide.

But in IoT applications, more then one device will connect to a Border Router usually. 

The IoT User Guide only explained the connection method of one device and the Border Router.

I tried to connect another device(TCP Client) in the same way on the basis of connecting one device,

but I could not connect successfully(only bt0 with the one device connected).

Can anyone tell me how to connect multiple devices with a BLE 6LoWPAN Border Router.

Thanks!

[Håkon Alseth]

Hi,

 

It sounds like you are lacking a route between the bt0 and ethX interface.

There are threads here on devzone where this is discussed, for instance in this thread.

How does your radvd config look? What's the output of "ifconfig" and "route -6 -n"?

 

Cheers,

Håkon

[michael lee]

Hi，Thank you for your reply.

Sorry，perhaps I did not write clearly. I mean

I used echo "connect 00:AA:BB:XX:YY:ZZ 1" > /sys/kernel/debug/bluetooth/6lowpan_control

to connected a device and PING it successfully.

But when I connected a another device, used 'hcitool con' could see 2 devices at the same time,

I could not PING any device anymore.

Does this mean that the BLE 6LoWPAN Border Router can only connect 1 device at the same time?

[Håkon Alseth]

This sounds like a kernel/bluez issue. Could you try using a newer version of bluez, and trying this with either an older or a newer kernel?

 

BR,

Håkon

[michael lee]

Thank you for your suggest.

I used the latest Raspbian(Kernel version 4.14) and Bluez( version 5.49) to try again,

got the same results as follows:

(1)connection a device

(2)connection 2 devices

The same test used Ubuntu 16.04(Kernel version 4.10) and bluez 5.30+NORDIC Linux-ble-6lowpan-joiner.

Different form the above test, one device could PING and the other one could not.

 

So, as you mentioned, this may be affected by the version of kernel and bluez.

[Håkon Alseth]

Hi,

 

I had a chat with our IoT group, and they confirmed this is a kernel issue. This patch is expected to fix your issue: https://www.spinics.net/lists/linux-bluetooth/msg72040.html (linked from this thread)

However; it is not in mainline linux. The IoT team also mentioned that they have had little issues with IPSP on kernel v4.11 (in ubuntu), so you could try that version, or raise an issue in the linux kernel bug register to try to push the above fix into mainline linux.

 

Best regards,

Håkon

[michael lee]

I got it. Thanks for the quick response!

[Sridhar Jonnavittula]

Hi Hakon,

I am using linux ubuntu kernel version 4.16 and bluetooth version 5.37. I applied the patch linked above post in my kernel. But when I tried to connect two 6lowpan nRF52840 devices at same time, initiating second connection is disturbing(disconnecting) first connection. Hence at a time only one connection exists.

Is this expected? How can I maintain two connections at same time?

Please help.

Thanks,

Sridhar

[Håkon Alseth]

I recommend that you ask in the kernel mailing lists about this. If the patch that is supposed to fix this introduces more issues, then this must be communicated back to the linux kernel community.

Kind regards,

Håkon