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.