Abstract: A traffic engineering method for reducing congestion and including estimating traffic over at least one link, having a defined capacity, between communication network nodes, thereby to determine an occupied portion of the link capacity and a complementary unoccupied portion of the link capacity, and based on the estimating step, selectably preventing allocation of the occupied portion of the link capacity to at least one capacity requesting client. Also, a method for reducing congestion in a communication network including at least one switch connected to a plurality of links, each having a defined physical capacity including a portion thereof which includes currently unutilized capacity, the method including computing an expected traffic load parameter over at least one switch, and based on the computing step, restricting allocation of at least a portion of at least one link's capacity if the expected traffic load parameter exceeds a threshold.