Native IPv6 Support for VPC Virtual Server Instances (VSIs)

1. Real-Life Scenario & Problem Statement: Our organization is currently deploying a globally distributed application that requires direct end-to-end connectivity for millions of edge devices. In our current IBM Cloud VPC setup, we are restricted to IPv4-only (Single Stack).

As the available pool of public IPv4 addresses continues to shrink and costs rise, we are forced to implement complex NAT (Network Address Translation) and Proxy layers. This architecture introduces significant latency, creates a single point of failure in our gateway, and complicates troubleshooting because the original client IP is lost before it reaches the VM. Furthermore, we are unable to meet several government and regulatory requirements that mandate IPv6 compatibility for new infrastructure.

2. Current Workaround(s):

• Multi-Cloud Deployment: We currently shift IPv6-dependent workloads to other cloud providers (such as AWS or Azure) that offer native Dual-Stack (IPv4/IPv6) support.

• Protocol Translation: We use external Load Balancers or 3rd-party CDNs to terminate IPv6 connections and "translate" them to IPv4 before they enter the IBM VPC, which increases our monthly egress and management costs.

3. Proposed Solution: We propose the implementation of Dual-Stack VPC networking within IBM Cloud. This should include:

• Subnet Level: The ability to assign a /64 IPv6 block to VPC subnets.

• VSI Level: Ability to assign at least one global unicast IPv6 address to a VSI's primary and secondary network interfaces.

• Security Groups/ACLs: Updated rules to support filtering based on IPv6 CIDR blocks.

• Public Gateways & Floating IPs: Support for IPv6 routing to the internet without requiring NAT64.

4. Benefits & Value:

• Reduced Complexity: Eliminates the need for NAT/Proxy layers, simplifying the network stack and reducing latency.

• Cost Savings: Reduces reliance on expensive public IPv4 addresses.

• Compliance: Enables us to meet Federal and Enterprise "IPv6-only" or "Dual-Stack" mandates.

• Scalability: Provides a virtually limitless address space for microservices and containerized workloads running on VSIs.

5. Impacted Users & Frequency:

• Users Impacted: Entire DevOps and Network Engineering teams, as well as end-users of our global applications.

• Frequency: This is a constant (24/7) impact. Every new deployment requires manual workarounds for the lack of IPv6, and every troubleshooting session is elongated by the complexity of our current NAT-heavy architecture.