Indicate the type of source of IPv6 address.
The value can be one of following:
'assignedIp': Assigned IPv6 address;
'assignedEUI64Ip': Assigned IPv6 address by using EUI-64
interface identifier;
'assignedAutoIp': Auto generated IPv6 address by user setting;
'autoIp': Auto generated IPv6 address as a result
of non-linklocal anycast/unicast address
configuration;
'dhcpv6': Assigned IPv6 address through DHCPv6
protocol;
'negotiate': Assigned IPv6 address through negotiation;
'cluster': Assigned IPv6 address through cluster
module.