LPR is used mostly for command line printing. Use cups if you can. I do not know if cups is installed by default in Ubuntu. To find out if it is running, open a web browser, and in the location bar, type http://localhost:631
and press enter. If cups is running, you will get the Cups home page on your system. If you get nothing, then it isn't installed, or not running.
To check if it is installed, open up Synaptic package manager, and look for it. Search cups. Install it if it isn't installed.
There are install instructions on Brothers web site for your printer. See this link.