Loadbalancer needs 8 ip for each subnet, but cannot works with ipv6-only?

Question

I am using load balancer.
My tasks are available in 3 ipv4 only subnets
today i created an. ipv6-only subnet
I would like to attach my loadbalancer also to the ipv6 subnet
I'm doing this, in cloud formation template

```
  LoadBalancer:
    Type: AWS::ElasticLoadBalancingV2::LoadBalancer
    Properties:
      LoadBalancerAttributes:
        - Key: idle_timeout.timeout_seconds
          Value: 60
      Name: TestElb
      Scheme: internet-facing
      SecurityGroups:
        - Ref: LoadBalancerSecurityGroup
      Subnets:
        - Fn::ImportValue: SubnetAArn-staging
        - Fn::ImportValue: SubnetBArn-staging
        - Fn::ImportValue: SubnetCArn-staging
        - Fn::ImportValue: Ipv6SubnetAArn-staging
```

I got this error: the subnet it refers is the ipv6-only

> Resource handler returned message: "Not enough IP space available in subnet-0c7125.....1f5. ELB requires at least 8 free IP addresses in each subnet. (Service: ElasticLoadBalancingV2, Status Code: 400,----)

How can I use ELB with ipv6 only subnets?

Answer

Hello realtebo,

please look at the solution it will be helpful for you

When attempting to attach an AWS Elastic Load Balancer (ELB) to an IPv6-only subnet, a limitation arises due to ELB's requirement of at least 8 free IP addresses in each subnet, which is designed for IPv4 subnets. Unfortunately, ELB doesn't currently support IPv6-only subnets. To work around this constraint, one option is to create dual-stack subnets supporting both IPv4 and IPv6, allowing ELB attachment to the IPv4 portion. Alternatively, consider using AWS Application Load Balancer (ALB), which supports dual-stack endpoints and thus accommodates IPv6 traffic. Another approach involves directly routing IPv6 traffic to instances if they support IPv6.

Could you please find the below link if you get more information and if you follow step by step:

https://docs.aws.amazon.com/vpc/latest/userguide/aws-ipv6-support.html

https://aws.amazon.com/blogs/networking-and-content-delivery/introducing-ipv6-only-subnets-and-ec2-instances/

Loadbalancer needs 8 ip for each subnet, but cannot works with ipv6-only?

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