Oracle Cloud Infrastructure Documentation

Assigning a Secondary Private IP Address

On Compute Cloud@Customer, when you create an instance, the instance automatically gets a VNIC, and the VNIC automatically gets a primary private IP address. You can add secondary private IP addresses to a VNIC. A VNIC can have up to 33 private IP addresses: one primary private IP address, and up to 32 secondary private IP addresses.

Creating a VNIC in the same subnet as another VNIC for the same instance can introduce asymmetric routing as described in Configuring VNICs. Instead, you can create a secondary private IP address for the existing VNIC that's in the subnet that you want.

See information about secondary private IP addresses, including use cases, in Managing Private IP Addresses.

After you perform the following procedure to assign a secondary private IP address, log onto the instance to configure the instance OS to use the new IP address. See Configuring the Instance OS for a Secondary IP Address.

Avoid entering confidential information in names and tags.

Moving a Secondary IP Address

In addition to adding a secondary private IP address, you can use this procedure to reassign (move) a currently assigned secondary private IP address to a different VNIC. Because the VNIC must be in the same subnet as the VNIC where the secondary private IP address is currently assigned, the new VNIC probably is attached to a different instance; as previously mentioned, having two VNICs in the same subnet in the same instance can introduce asymmetric routing.

To move a secondary private IP address, see the Unassign if assigned or --unassign-if-already-assigned options in the following procedures.

You can't move a VNIC primary private IP address.

If a public IP address object is assigned to a secondary private IP address object, and you move that secondary private IP address object to another VNIC, the public IP address object moves with it.

    1. On the Compute Cloud@Customer Console Dashboard, click Compute/View Instances.

    2. At the top of the page, select the compartment that contains the instance for which you want to add a secondary private IP address.

    3. Click the name of the instance to which you want to add a secondary private IP address.

      The instance details page is displayed.

    4. Under Resources, click Attached VNICs.

      The primary VNIC and any secondary VNICs attached to the instance are displayed.

    5. Click the name of the attached VNIC to which you want to add a secondary private IP address.

    6. On the VNIC details page, under Resources, click IP Addresses.

    7. Click Assign Secondary Private IP Address.

    8. In the Attach Private IP dialog box, all input fields are optional.

      • IP Address: If you don't enter an address, an IP address from the subnet CIDR is automatically assigned.

        If you enter an address, the IP address must be within the CIDR block for the subnet. You can enter a secondary private IP address that's already assigned to another VNIC in the subnet. You can't enter a primary private IP address.

        If you enter an IP address that's already assigned, see the following option.

      • Unassign if assigned: In the previous option, if you entered a secondary private IP address that's already assigned, select this item to move that private IP address. The address will be unassigned from the VNIC where it's currently assigned and reassigned to this VNIC.

        If you entered an IP address that's already assigned and you don't select this item, this secondary private IP assignment operation fails.

      • Hostname: Enter the hostname to be used for DNS within the cloud network. This option is available only if the VCN and subnet both have DNS labels.

    9. Click Attach IP Address.

      The new secondary private IP address is shown in the table.

    10. Configure the new secondary private IP address in the instance. See Configuring the Instance OS for a Secondary IP Address.

  • Use the network vnic assign-private-ip command and required parameters to assign a secondary private IP address to the specified VNIC. The secondary private IP must be in the same subnet as the VNIC. 

    oci network vnic assign-private-ip --vnic-id <vnic_OCID> [OPTIONS]

    For a complete list of CLI commands, flags, and options, see the Command Line Reference.

  • Use the PrivateIp operation to assign a secondary private IP address to the specified VNIC. The secondary private IP must be in the same subnet as the VNIC.

    For information about using the API and signing requests, see REST APIs and Security Credentials. For information about SDKs, see Software Development Kits and Command Line Interface.