Keeping a DSL connection alive

Anyone have any ideas on how I can make OS X 10.2.3 Server keep my DSL connection alive? I have the DSL modem connected to my built-in ethernet card, and under System Preferences->Network, I am using PPPoE, with the appropriate details entered. Under PPPoE options, I have ticked the box which says 'Connect automatically when needed', but it doesn't seem to do what I want. I need to have the server keep the connection alive, even when the server isn't logged on.