A new policy that can effectively handle message routing and flow control simultaneously in a packet switched computer network is presented. In such a policy, a traffic threshold level is assigned for each channel in the network. If all the channels along the preassigned primary route from current node to its destination do not exceed the predetermined traffic threshold, then the primary route is used. Otherwise, alternative route(s) are used to share the traffic load. When all the alternative routes from a source to a destination become unavailable, then the input traffic from that source to that destination is temporarily rejected. Simulation results of the behavior and performance of such a routing and flow control policy are presented. The implementation of the policy is also discussed. Simulation results reveal that this new policy is simpler to implement and yields better performance than that of distributed routing algorithm and buffer allocation flow control policy, which are currently being used in many packet switched networks.