Server Load Balancer:Change the network type of an ALB instance

Instance network types

Instance type	Internet-facing ALB instance	Internal-facing ALB instance
Scenario	You need to access backend services over the Internet.	You only need to access backend services from an Alibaba Cloud VPC.
IP address assignment	An elastic IP address (EIP) and a private IP address are assigned. You can associate an Anycast EIP with the ALB instance.	Only a private IP address is assigned.
Access method	Accessible over both the Internet and a private network.	Accessible only over a private network.
Diagram
Billing	Instance fees, LCU fees, and Internet data transfer fees (charged on the EIP) apply.	Only instance fees and LCU fees apply.

IP versions

Dual-stack is supported only in some regions.

The network type of a dual-stack ALB instance is determined by its IPv4 address. If the IPv4 address is private, the instance is internal-facing; if the IPv4 address is public, the instance is Internet-facing.

You can only create new dual-stack instances. Upgrading an existing IPv4 instance to dual-stack is not supported.

Access control list (ACL) entries support only IPv4 addresses.

An upgraded ALB instance assigns private IPv4 and IPv6 addresses for external services from each specified vSwitch.

Public IP address types

ALB supports two types of public IP addresses:

Prerequisites

Ensure the following:

• An ALB instance is created. Create an ALB instance

Switch an IPv4 ALB instance from internal to Internet-facing

After this change, assign EIPs or Anycast EIPs to the ALB instance. Internet data transfer fees apply. EIP billing, Anycast EIP billing.

1. Log on to the ALB console.

2. In the top navigation bar, select the region of the ALB instance.

3. On the Instances page, click the ID of the internal-facing ALB instance.

4. On the Instance Details tab, find Network Type in the Basic Information section and click Change Network Type next to IPv4:Private.

5. In the Change Network Type dialog box, select an IP Type and assign public IP addresses. Option A: Assign EIPs Option B: Assign Anycast EIPs For Anycast EIP limits and procedures, see Associate an Anycast EIP for nearby access across multiple regions.

   1. Set IP Type to EIP.

   2. Select Purchase EIP from the Assign EIP drop-down list, or select an existing Anycast EIP, and click OK.

      Note

      • Assign an EIP to each zone in the list.

      • To use an EIP with a specific IP address, replace the EIP by adding or removing zones. Modify the configurations of ALB instances.

      • Changing the network type automatically releases or disassociates all assigned EIPs. Released EIPs cannot be restored.

        • View EIP details in the EIP console.

        • Purchased EIPs use pay-as-you-go billing with pay-by-data-transfer metering, BGP (Multi-ISP) lines, and Anti-DDoS Origin Basic protection.

      Note

      • Assign Anycast EIPs to all zones in the list.

      • Switching an ALB instance to internal-facing or releasing it automatically disassociates and releases associated Anycast EIPs.

      • View Anycast EIP details in the Anycast EIP console.

6. Click OK.

7. Return to the Instance Details tab and verify the Network Type value. The change takes about 1 minute. When IPv4 shows Public, the ALB instance is Internet-facing.

Switch an IPv4 ALB instance from Internet-facing to internal

1. Log on to the ALB console.

2. In the top navigation bar, select the region of the ALB instance.

3. On the Instances page, click the ID of the Internet-facing ALB instance.

4. On the Instance Details tab, find Network Type in the Basic Information section and click Change Network Type next to the public IPv4 address.

5. In the confirmation message, review the impacts and click OK.

6. Return to the Instance Details tab and verify the Network Type value. The change takes about 1 minute. When IPv4 shows Private, the ALB instance is internal-facing.

Switch a dual-stack ALB instance to public IPv6

To switch from private IPv4 to public IPv4 on a dual-stack instance, follow the same steps as Switch an IPv4 ALB instance from internal to Internet-facing.

The following steps describe how to switch to public IPv6.

1. Log on to the ALB console.

2. In the top navigation bar, select the region of the ALB instance.

3. On the Instances page, click the ID of the internal-facing ALB instance.

4. On the Instance Details tab, find Network Type in the Basic Information section and click Change Network Type next to the IPv6 address.

5. In the Change Network Type message, review the impacts and click OK.

   Note

   If the VPC lacks an IPv6 gateway, follow the console prompts to create one.

6. Return to the Instance Details tab and verify the Network Type value. The change takes about 1 minute. When IPv6 shows Public, the ALB instance supports public IPv6 traffic.

Switch a dual-stack ALB instance to private IPv6

To switch from public IPv4 to private IPv4 on a dual-stack instance, follow the same steps as Switch an IPv4 ALB instance from Internet-facing to internal.

The following steps describe how to switch to private IPv6.

1. Log on to the ALB console.

2. In the top navigation bar, select the region of the ALB instance.

3. On the Instances page, click the ID of the Internet-facing ALB instance.

4. On the Instance Details tab, find Network Type in the Basic Information section and click Change Network Type next to the IPv6 address.

5. In the Disable Elastic IPv6 message, review the impacts and click Disable.

6. Return to the Instance Details tab and verify the Network Type value. The change takes about 1 minute. When IPv6 shows Private, the ALB instance no longer supports public IPv6 traffic.

Limitations

Billing

ALB is billed hourly, rounded up to 1 hour. Network type changes take effect immediately, but the current hour bills at the previous type. See ALB billing.

References

• Associate Anycast EIPs with an ALB instance

• ALB billing

• EIP billing

• Anycast EIP billing

• IPv6 gateway billing

• Configure a CNAME record

• Associate an Anti-DDoS (Enhanced) EIP with an ALB instance

• What types of EIPs can be associated with ALB instances?