Add STANDARDS section to the gre(4) manual page Obtained from: OpenBSD
- We do not have MPLS as described in RFC 4023 or NVGRE in RFC 7637 as a kernel feature.
- RFC 8086 (GRE-in-UDP) is supported.
- I am not sure why WCCP I-Ds should be listed here. They use GRE but it is usually implemented by a userland daemon, not by kernel.