Implementing fixed points in network state updates using generation numbers

For a subscriber controller of a network control system that manages a plurality of forwarding elements in order to implement a plurality of logical datapath sets, a method comprising:

• receiving a first publication comprising network state data, the first publication having a first generation number from a first publisher controller;
• receiving a second publication comprising network state data, the second publication having a second generation number from a second publisher controller;
• when the first generation number is more current than the second generation number, storing the first publication;
• when the second generation number is more current than the first generation number, storing the second publication;
• and
• computing a set of outputs using the stored publication for implementing the plurality of logical datapath sets.

For a particular publisher controller in a network control system comprising a plurality of controllers that manage a plurality of forwarding elements in order to implement a plurality of logical datapath sets, the plurality of controllers comprising a plurality of publisher controllers, a method comprising:

• identifying a first set of publications that the particular publisher controller is responsible for publishing, the publication including network state data;
• publishing the first set of publications with a first generation number to a set of subscriber controllers of the plurality of controllers;
• detecting a change in an allocation of publication responsibilities of at least one publisher controller of the plurality of publisher controllers;
• determining a second generation number based on the changed allocation;
• and
• publishing, with the second generation number, a second set of publications for which the particular publisher controller is responsible based on the changed allocation.