Google BBR support comes builtin in kernel > 4.9 but needs to be enabled at compile time.
In VyOS to enable it just modify `packages/vyos-kernel/arch/x86/configs/x86_64_vyos_defconfig`
around line 940 uncomment
```#CONFIG_TCP_CONG_BBR is not set```
and set it
```
CONFIG_TCP_CONG_BBR=m
```
Then in VyOS you can switch to BBR by simply issueing `system sysctl` config commands