I am working on a 4 later board and I have areas of the layout already routed through vias and tracks. I would love as I am working with Eagle 6 to start the auto router and not to cancel my previous work. In particular I have ground and power planes. I defined already connections to them through vias. But all the time I run the auto router it happens that it changes the connections and or cancel them while I would like the autorouter to continue from my connections and routing the rest of the signals on my defined power and ground planes without changing the tracks already defined.