1. A method for configuring a set of logical routers in a logical network, the method comprising: receiving (i) a configuration for a first logical router comprising an advertised route and (ii) a configuration for a second logical router comprising a set of allowable routes for the second logical router to include in its routing table, wherein the first logical router connects to the second logical router; determining whether the set of allowable routes for the second logical router includes the advertised route as an allowed route from the first logical router; only when the advertised route is an allowed route from the first logical router, adding the advertised route to a routing table for at least one component of the second logical router; and distributing data regarding the routing table to a plurality of physical machines that implement the second logical router.