IPv4 and IPv6 Dual-Stack Network

What Is an IPv4/IPv6 Dual-Stack Network?

IPv4 and IPv6 dual-stack allows your resources, such as ECSs, to use both IPv4 and IPv6 addresses for private and public network communications. For example, if ECSs uses the IPv4/IPv6 dual-stack network:

• ECSs can communicate with each other using private IPv4 addresses.
• ECSs can communicate with the Internet after they are bound with EIPs.
• ECSs can communicate with each other using IPv6 addresses.
• ECSs can communicate with the Internet after their IPv6 addresses are associated with bandwidths.

If you select Enable for IPv6 CIDR Block when creating a subnet, an IPv6 CIDR block will be automatically assigned to the subnet.

Basic operations on IPv4 and IPv6 dual-stack networks are the same as those on IPv4 networks, except some parameters. Check the console pages for details.

Notes and Constraints

• The IPv4/IPv6 dual-stack function is currently free, but will be billed at a later date (price yet to be determined).
• Only ECS flavors that support IPv6 addresses can use IPv4/IPv6 dual-stack networks.
  You can use either of the following methods to check which ECS flavors support IPv6 addresses:

  • On the ECS console, click Buy ECS. On the displayed page, view the ECS flavors.

    If an ECS flavor has the IPv6 parameter with the value of Yes, the ECS flavor supports IPv6 addresses.

  • On the ECS Specifications page, click the link of your desired ECS specifications for detailed information, and check the ECS flavors that support IPv6 in the table of ECS features.

    For example, if you want to check the flavors of general computing-plus ECSs that support IPv6:

    1. Open the ECS Specifications page.
    2. Under General Computing-Plus, click the link for detailed information.
       Figura 1 Link for detailed information
       
    3. On the General Computing-plus ECSs page, check whether IPv6 is supported in the table of ECS features.
       Figura 2 General computing-plus ECSs
       

IPv6 Application Scenarios

If your ECS flavor does not support IPv6 addresses, you can enable the IPv6 EIP function to allow communications using IPv6 addresses. For details, see Tabela 2.

Tabela 2 Application scenarios of IPv6 EIPs

Application Scenario	Description	Subnet	ECS
Public communication using IPv6 addresses	Your applications deployed on ECSs need to provide services accessible from the Internet using IPv6 addresses.	IPv4 CIDR block	Private IPv4 address IPv4 EIP (with IPv6 function enabled): used for public communication using IPv4 and IPv6 EIPs

Figura 3 Application scenarios of IPv6 networks

Basic Operations

Creating an IPv6 Subnet

Create an IPv6 subnet by following the instructions in Criação de uma sub-rede para a VPC. Select Enable for IPv6 CIDR Block. An IPv6 CIDR block will be automatically assigned to the subnet. IPv6 cannot be disabled after the subnet is created. Currently, customizing IPv6 CIDR block is not supported.

Viewing In-Use IPv6 Addresses

In the subnet list, click the subnet name. On the displayed page, view in-use IPv6 addresses on the IP Addresses tab page.

Adding a Security Group Rule (IPv6)

Add a security group rule with Type set to IPv6 and Source or Destination set to an IPv6 address or IPv6 CIDR block.

Adding a Network ACL Rule (IPv6)

Add a network ACL rule with Type set to IPv6 and Source or Destination set to an IPv6 address or IPv6 CIDR block.

Figura 4 Adding a network ACL rule (IPv6)

Adding a Route (IPv6)

Add a route with Destination and Next Hop set to an IPv4 or IPv6 CIDR block. For details about how to add a route, see Adição de uma rota personalizada. If the destination is an IPv6 CIDR block, the next hop can only be an IP address in the same VPC as the IPv6 CIDR block.

If the destination is an IPv6 CIDR block, the next hop type can only be an ECS, extension NIC, or virtual IP address. The next hop must also have IPv6 addresses.

Dynamically Assigning IPv6 Addresses

After an ECS is created successfully, you can view the assigned IPv6 address on the ECS details page. You can also log in to the ECS and run the ifconfig command to view the assigned IPv6 address.

If an IPv6 address fails to be automatically assigned or the selected image does not support the function of automatic IPv6 address assignment, manually obtain the IPv6 address by referring to Dynamically Assigning IPv6 Addresses.

If an ECS is created from a public image:

Before enabling dynamic IPv6 address assignment for a Linux public image, check whether IPv6 is supported and then check whether dynamic IPv6 address assignment has been enabled. Currently, all Linux public images support IPv6, and dynamic IPv6 address assignment is enabled for Ubuntu 16 by default. You do not need to configure dynamic IPv6 address assignment for the Ubuntu 16 OS. For other Linux public images, you need to enable this function.