Example routing systems and methods are described. In one implementation, a first set of routing systems is interfaced with a network connection via a network interface. A second set of routing systems interfaced with a secure system is configured to receive information from the first set of routing systems via a first unidirectional data channel. In some embodiments, the first set of routing systems is configured to receive information from the second set of routing systems via a second unidirectional data channel. The secure system is not visible from the network interface.