Does Rsync use internet data to transfer files remotely?

Question

I have learned to use rsync yesterday. I use it to push files to my Android device (Termux) and I even pull files from my Android device (Termux).

I use this command to push:

rsync -e 'ssh -p 8022' -vaP <source> <username>@<ipaddresss>:/sdcard/rsync 

And I use this command to pull:

rsync -e 'ssh -p 8022' -vaP <username>@<ipaddresss>:/sdcard/rsync/* /home/me/rsync/

And I noticed that the transfer rate of files are more than 16000Kbps, which is way faster than my internet connection (which is slower than 250Kbps).

So, here's my question: doesn't rsync use internet data to transfer files remotely?

Note: Both my laptop and smartphone are connected to the same Wi-Fi network. :)

Answer 1

Since your phone is connected to the same local network as you laptop and since you presumably use the local addresses of the devices on that local network (i.e. not any public addresses or names), no data will ever be transferred through your Internet provider's router. It's on that router that your bandwidth is limited. This means that rsync will be able to use the full bandwidth of your local network.

If you move your phone outside of your local network and connect to your laptop with some public IP or name, then you will be restricted by your service provider's limits (and possibly by congestions etc. on intermediate networks).