• RFC 2407 - The Internet IP Security Domain of Interpretation for ISAKMP, November 1998 (Standards Track, Obsoleted by RFC 4306)

With IPsec, the protocols for IPv4 and IPv6 are fairly similar, and for the most part, there is a single set of standards that cover both IPv4 and IPv6. The main difference is the almost universal presence of NAT in IPv4 and total absence of it in IPv6.

The Internet Key Exchange (IKEv1 and IKEv2) is based on ISAKMP (Internet Security Association and Key Management Protocol), which is a framework for key exchange. It uses parts of the Oakley and SKEME (Secure Key Exchange MEchanism for Internet) protocols within this framework.

The official name for this technology (as used by the IETF) is The Security Architecture for the Internet Protocol. Since it takes place in the Internet Layer, protocols at the Transport and Application Layers need not even be aware of it, and do not need to be modified to use it. In effect, you build secure tunnels at the IP layer that the higher layer protocols go through unmodified.