Huawei Technologies Oracle Huawei Technologies Facebook This document specifies a method of encapsulating network protocol packets within GRE and UDP headers. This GRE-in-UDP encapsulation allows the UDP source port field to be used as an entropy field. This may be used for load-balancing of GRE traffic in transit networks using existing Equal-Cost Multipath (ECMP) mechanisms. There are two applicability scenarios for GRE-in-UDP with different requirements: (1) general Internet and (2) a traffic-managed controlled environment. The controlled environment has less restrictive requirements than the general Internet.