Roadwarrior carol proposes to gateway moon the cipher suite
AES_GCM_16_256 both for IKE and ESP by defining ike=aes256gcm16-aesxcbc-modp2048
(or alternatively aes256gcm128) and esp=aes256gcm16-modp2048 in ipsec.conf,
respectively.
A ping from carol to alice successfully checks the established tunnel.