This topic does not apply to Oracle Cloud at Customer.
A preshared key (PSK) in the 128-bit/SHA1 format.
(Optional) A range of 8000 private IP addresses. These should be provided as network prefixes in the CIDR format (for example, n.n/19). When you create instances or restart existing instances, the private IP address of each instance is dynamically assigned from this range of IP addresses. Note that when your Compute Classic account is provisioned, a range of private IP addresses is assigned from the 100.64/10 address range. You can either use this assigned range or specify another range of private IP addresses. An 8000-address block can meet the IP address requirements of up to 2000 instances.
Ensure that the range of IP addresses that you provide doesn’t overlap with the private IP addresses used by other devices on your on-premises network.
Also check that the private IP addresses of existing Compute Classic instances do not conflict with private IP addresses used by any of your on-premises devices. Such a conflict becomes relevant only when you configure a VPN tunnel and your Compute Classic instances become an extension of you on-premises network.