Internet Key Exchange (IKE) Protocol Extensions apply to the IKE Protocol versions 1 and 2, as specified in [RFC2407], [RFC2408], [RFC2409], [RFC3947], and [RFC4306]. These extensions provide additional capabilities to IKE, including interoperation between different revisions of the network address translation traversal (NAT-Traversal or NAT-T) specification, fragmentation of large IKE version 1 messages, authentication by using cryptographically generated addresses (CGAs), fast failover when communicating with a cluster of hosts, easier interoperation with non-Internet Protocol security (IPsec)–capable peers, acknowledgment of security association (SA) deletion messages, denial of service protection, IKE security association correlation (IKEv2), and IKE server internal addresses configuration attributes (IKEv2).
Sections 1.8, 2, and 3 of this specification are normative and can contain the terms MAY, SHOULD, MUST, MUST NOT, and SHOULD NOT as defined in RFC 2119. Sections 1.5 and 1.9 are also normative but cannot contain those terms. All other sections and examples in this specification are informative.