AWS RDS Goes Dual-stack: IPv4 and IPv6

I’ve spoken of the IPv6 transition for many, many years. Last month I gave a presentation at the AWS User Group (Perth) on this, and included a role play on packets through the network.

Earlier in 2022 we saw AWS VPC support IPv6-only subnets, a great way to scale out vast numbers of instances with 18 billion billion addresses per subnet. Today sees one of the most commonly used services with virtual machines – managed databases via the Relational Database Service – finally get its first bit of IPv6 support!

When creating a database, you now have a new option as shown here:

AWS Console Wizard for starting an RDS instance

It’s worth noting that, the Database Subnet defined in RDS can (at this point in time) select subnets that are either IPv4 only, or dual stack IPv4 and IPv6. To put this clearer, RDS is not (yet?) supporting IPv6 only deployment.

But that’s a small limitation. The power of scale-out of application servers in vast subnets can now natively talk to a dual-stack deployed RDS Instances using IPv6 as the transport protocol. No other proxies or adaptors or work-around required.

Of course, there’s more managed AWS services to even get this far – ElasticCache, for example, or even IPv6 as first class (eg: CloudFront origin fetch).

This is incremental improvement.

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