BBR is the optimization for the tcp, and it can increase the network speed significant. So it's the same as kcptun.

Check the kernel version, the kernel is already 4.9+, so it already support bbr

pi@raspberrypi:~ $ uname -a
Linux raspberrypi 4.9.35-v7+ #1014 SMP Fri Jun 30 14:47:43 BST 2017 armv7l GNU/Linux

==== Enable bbr ====

pi@raspberrypi:~ $  sudo sysctl net.ipv4.tcp_congestion_control=bbr
net.ipv4.tcp_congestion_control = bbr
pi@raspberrypi:~ $  lsmod |grep bbr
tcp_bbr                 6366  18
pi@raspberrypi:~ $  sysctl net.ipv4.tcp_available_congestion_control
net.ipv4.tcp_available_congestion_control = bbr cubic reno
pi@raspberrypi:~ $  sysctl net.ipv4.tcp_congestion_control
net.ipv4.tcp_congestion_control = bbr