The host carol sets up a tunnel connection to gateway moon. It requests
both an IPv4 and an IPv6 virtual IP via the IKEv2 configuration payload by using
vips = 0.0.0.0,0::0. GGateway moon assigns virtual IPs addresses
from persistent pools stored in an SQL database.
The established tunnel carries both IPv4 and IPv6 in an IPv4 encapsulated tunnel.