A method of manages a set of managed forwarding elements that forward data between machines. The method configures (1) a first managed forwarding element to operate in a first network that uses first and second address spaces that at least partially overlap with each other, (2) a second managed forwarding element to operate in a second network that uses the first address space, and (3) a third managed forwarding element to operate in a third network that uses the second address space. A machine in the second network and a machine in the third network have an identical address that belongs to both the first and second address spaces. The method directs the first managed forwarding element to connect to the second and third managed forwarding elements in a manner that enables the first managed forwarding element to forward data from a machine in the first network to the machine in the second network via the second managed forwarding element.