This document describes how to extend the Internet Key Exchange Protocol Version 2 (IKEv2) to allow multiple key exchanges to take place while computing a shared secret during a Security Association (SA) setup.

This document utilizes the IKE_INTERMEDIATE exchange, where multiple key exchanges are performed when an IKE SA is being established. It also introduces a new IKEv2 exchange, IKE_FOLLOWUP_KE, which is used for the same purpose when the IKE SA is being rekeyed or is creating additional Child SAs.

This document updates RFC 7296 by renaming a Transform Type 4 from "Diffie-Hellman Group (D-H)" to "Key Exchange Method (KE)" and renaming a field in the Key Exchange Payload from "Diffie-Hellman Group Num" to "Key Exchange Method". It also renames an IANA registry for this Transform Type from "Transform Type 4 - Diffie- Hellman Group Transform IDs" to "Transform Type 4 - Key Exchange Method Transform IDs". These changes generalize key exchange algorithms that can be used in IKEv2.