Indicates the user-supplied encryption option of this VLAN
attachment (interconnectAttachment). Can only be specified at
attachment creation for PARTNER or DEDICATED attachments. Possible
values are: - NONE - This is the default value, which means that the
VLAN attachment carries unencrypted traffic. VMs are able to send
traffic to, or receive traffic from, such a VLAN attachment. - IPSEC
The VLAN attachment carries only encrypted traffic that is
encrypted by an IPsec device, such as an HA VPN gateway or
third-party IPsec VPN. VMs cannot directly send traffic to, or
receive traffic from, such a VLAN attachment. To use HA VPN over
Cloud Interconnect, the VLAN attachment must be created with this
option.