IPsec Gateway Failover Protocol
The Internet Key Exchange version 2 (IKEv2) protocol has computational and communication overhead with respect to the number of round-trips required and cryptographic operations involved. In remote access situations, the Extensible Authentication Protocol is used for authentication, which adds additional latency. To re-establish security associations (SA) upon a failure recovery condition is time consuming, especially when an IPsec peer, such as a VPN gateway, needs to re-establish a large number of SAs with various end points. A high number of concurrent sessions might cause additional problems for an IPsec peer during SA re-establishment. In many failure cases it would be useful to provide an efficient way to resume an interrupted IKE/IPsec session. This document proposes an extension to IKEv2 that allows a client to re-establish an IKE SA with a gateway in a highly efficient manner, utilizing a previously established IKE SA. A client can reconnect to a gateway from which it was disconnected, or alternatively migrate to another gateway that is associated with the previous one. The proposed approach conveys IKEv2 state information, in the form of an encrypted ticket, to a VPN client that is later presented to the VPN gateway for re-authentication. An encrypted ticket cannot be decrypted by a VPN client but allows a VPN gateway to restore state for faster session state setup.