Does transferring files over a local network use up internet bandwidth

Question

We've got a server on our network and some drives on that server mapped to our desktops. When I transfer a file over, windows task manager reports 100% network utilization on local area network, which is great.

How can I check whether this consumes internet bandwidth or not?

Answer 1

You can disconnect your Internet, and should find that it still works fine, unless there is some strange reason the server relies on the Internet.

Depending on your router, it could slow down the network, including Internet access, for other users, but will not affect the Internet connection.

Answer 2

Short answer is no it should not.

Local network usage does not constitute internet usage, so just disconnect your cable / adsl line and test. It should still be pumping the data at full capacity, but it should not be using the net for it.

Answer 3

The short answer is that no it should not because packets sent from your computer to a server on the same local network should never leave the local network assuming the network is sensibly configured.

However, the short answer makes another assumption about your network, which is that your local network is actually local. Many organisations now outsource services to the cloud and use various technologies to tunnel data packets across network boundaries (e.g. over the public Internet) while making it all look like the server has a local IP address.

Alternatively, the server could be in your network but at another location, such as a remote data centre or another office, which would similarly require packets to tunnel across the public network (Internet).

The upshot is that large file you're transferring to a file server on your network could actually be chewing up Internet bandwidth. The only way to know for sure is to ask someone who understands your network topology and knows for sure where the server is both physically and logically.