For a particular controller for managing managed forwarding elements that forward data in a network, a method for computing forwarding state using a set of inputs from a first controller and a second controller that is a back up controller for the first controller is described. The method receives a first subset of the set of inputs from the first controller. After failure of the first controller, the method receives a second subset of the set of inputs from the second controller. At least one input of the second subset of the set of inputs is duplicative of an input in the first subset. The method computes forwarding state using the first and second subsets of the inputs but without using the duplicative input.