Answer
In BlueZ, some commands such as l2test or l2ping are able to generate traffic on L2CAP layer. To test performance and reliability, you can use the l2test command:
On the server, run the command:
l2test -I 2000 -r
On the client side, run the command:
l2test -O 2000 -s XX:XX:XX:XX:XX:XX