http://www.rfc-editor.org/rfc/rfc6290.txt
RFC 6290: A Quick Crash Detection Method for the Internet Key Exchange Protocol (IKE), Y. Nir, D. Wierbowski, F. Detienne, P. Sethi2011-06-01T23:00:00-00:00When an IPsec tunnel between two IKEv2 peers is disconnected due to a restart of one peer, it can take as much as several minutes for the other peer to discover that the reboot has occurred, thus delaying recovery. In this text, we propose an extension to the protocol that allows for recovery immediately following the restart. [STANDARDS-TRACK]