RFC 4891:Using IPsec to Secure IPv6-in-IPv4 Tunnel...
RFC-Ref

end-to-end communication


Click on the red underlined text to get to the source

... Please note that using IPsec for the scenarios described in Figures 1, 2, and 3 does not aim to protect the end-to-end communication. It protects just the tunnel part. It is still possible for an IPv6 ...



Google
Web
RFC-Ref