Reactive Routing is an innovation in space networking by which unplanned changes in link performance, detected by the Physical Layer (Cognitive Radio and Media Access Controller), are used to generate automatic and immediate adjustments to the “contact plans” on which route computation in delay-tolerant networking (DTN) can be based. These changes in contact plans will result in route revisions that will reallocate traffic load per the revised transmission opportunities, improving network performance while reducing operations costs.