Stop Google Chrome from Using So Much Bandwidth at the CfA

I recently discovered that whenever I start Google Chrome at work, my computer’s bandwidth consumption goes to ~450 KiB/s and just sits there indefinitely. No matter what website I visit or anything.

Background downloads? Infinite loop?

No. mDNS. The CfA networks apparently transmit mDNS traffic between just about everybody, and it seems that there are so many mDNS-enabled machines that the traffic ends up being completely continuous.

This StackExchange answer ended up doing the trick for me. Apparently there are no user-facing, or even hidden, preferences to control the Chrome device discovery code that causes all of the traffic. You have create a “policy file” to alter the behavior:

echo '{ "EnableMediaRouter": false }' |sudo tee /etc/opt/chrome/policies/managed/no-mdns.json

It doesn’t happen on macOS because there Chrome hooks into the system mDNS implementation, which seems to be smarter about not polling everything all of the time.