Loopback-based IPv4/IPv6 over IPv4 or IPv6 GRE encapsulation

This feature enables loopback-based GRE encapsulation of IPv4 and IPv6 payload traffic over IPv4 or IPv6 transport networks. You can use loopback-based tunnel processing to connect disjoint network segments by encapsulating the original packets in GRE and an outer IPv4 or IPv6 header. This capability allows IPv4 and IPv6 traffic to traverse intermediate IP networks while preserving the original inner packet headers between tunnel endpoints.