Configuring EC2 + ELB as IPv6 only

Question

Hello:
Is it viable to configure a (webserver) EC2 + ELB  with IPv6 stack-only? What would happen with those clients that don't have IPv6 yet? Since IPv4 are getting more expensive now, we would like to migrate our resources to IPv6 only, but I'm not sure if this would work as a general solution...
I would appreciate any help or comment on this.

Thanks

Accepted Answer

As Riku_Kobayashi correctly stated, internet-facing ALBs can now be configured without public IPv4 addresses. To answer you question about IPv4 clients, this would make them unable to connect. The way you can make the setup work without your users losing access is by placing a CloudFront distribution in front of your ALB.

CloudFront shares its public IPv4 address space across vast numbers of different customers' distributions (when using the default SNI-only mode for HTTPS, which you should also do), and that's why you aren't charged for public IPv4 addresses, despite your site being accessible over IPv4 via CloudFront.

Answer

Hello.

EC2 can be changed to IPv6 only.  
https://aws.amazon.com/jp/blogs/networking-and-content-delivery/introducing-ipv6-only-subnets-and-ec2-instances/

However, ALB cannot be configured for IPv6 only as of May 2024, so it will be a dual stack configuration using IPv4 and IPv6.  
In other words, you cannot erase public IPv4 when using ALB.  
https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-ip-address-type.html  
https://repost.aws/knowledge-center/elb-configure-with-ipv6

> What would happen with those clients that don't have IPv6 yet?

I think it is possible for IPv4-only clients to access the application if the ALB is dual stacked.

Configuring EC2 + ELB as IPv6 only

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