Cisco Systems Juniper Networks Ericsson Generic Routing Encapsulation (GRE) can be used to carry any network layer protocol over any network layer protocol. GRE procedures are specified for IPv4, used as either the payload or delivery protocol. However, GRE procedures are not specified for IPv6, used as either the payload or delivery protocol. This document specifies GRE procedures for IPv6, used as either the payload or delivery protocol, and updates RFC 2784, the original GRE specification.