This paper presents a method for dynamic load balancing in data networks. When multiple routes are available, it determines their load shares as a function of a composite metric that takes into account the paths? length and load. A general resource preservation mechanism is also presented that complements the proposed random routing strategy when the network is heavily loaded. We compare our approach with trunk reservation in the particular case of fully meshed networks and evaluate its performance in any network, where an equivalent mechanism is missing. We validate our approach by means of simulation and provide insights on the routing solutions that it obtains.