Currently data packets going over a DPS+IPsec tunnel have a fixed source IP, destination IP, protocol, source port and destination port after encapsulation for a given DPS path. Because of this, there is no good way to load-balance the tunneled traffic. However, to improve performance there is a need to load-balance the tunneled traffic. 

This feature provides a way to distinguish groups of flows within encrypted GRE tunnels. That enables downstream forwarding devices to process multiple flows in parallel while maintaining packet order within individual flows. Parallel processing offers the opportunity for significant aggregate throughput improvement.