Add or remove an IPv6 CIDR block from your subnet - Amazon Virtual Private Cloud
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Add or remove an IPv6 CIDR block from your subnet

You can associate an IPv6 CIDR block with an existing subnet in your VPC. The subnet must not have an existing IPv6 CIDR block associated with it.

If you no longer want IPv6 support in your subnet, but you want to continue to use your subnet to create and communicate with IPv4 resources, you can remove the IPv6 CIDR block.

Before you can remove an IPv6 CIDR block, you must first unassign any IPv6 addresses that are assigned to any instances in your subnet.

To add or remove an IPv6 CIDR block to a subnet

  1. Open the Amazon VPC console at https://console.amazonaws.cn/vpc/.

  2. In the navigation pane, choose Subnets.

  3. Select your subnet and choose Actions, Edit IPv6 CIDRs.

  4. To add a CIDR, choose Add IPv6 CIDR, choose a VPC CIDR block, enter a Subnet CIDR block, and choose a netmask length that's equal to or more specific than the netmask length of the VPC CIDR. For example, if the VPC pool CIDR is /50, you can choose a netmask length between /50 to /64 for the subnet. Possible IPv6 netmask lengths are between /44 and /64 in increments of /4.

  5. To remove a CIDR, find the IPv6 CIDR block and choose Remove.

  6. Choose Save.

To associate an IPv6 CIDR block with a subnet using the Amazon CLI

Use the associate-subnet-cidr-block command.

To disassociate an IPv6 CIDR block from a subnet using the Amazon CLI

Use the disassociate-subnet-cidr-block command.