IPv6 Dual-Stack Overview
FPT Cloud Console Portal supports Dual-Stack networking — letting network resources operate over both IPv4 and IPv6 on the same infrastructure at the same time.
What is Dual-Stack
Dual-Stack means a network resource (VPC, Subnet, Instance) can use both an IPv4 and an IPv6 address simultaneously. Unlike IPv4-only or IPv6-only, dual-stack lets you:
- Keep compatibility with your existing IPv4 systems
- Prepare for the IPv6 transition roadmap under VNNIC's plan through 2030
- Allocate a virtually unlimited pool of IPv6 addresses to cloud resources
Overall architecture
FPT Cloud configures a General-type VPC with dual-stack (on request)
└─► VPC receives an IPv6 Parent Pool (/64)
└─► Tenant creates a dual-stack Subnet
└─► Subnet automatically receives a /64 from the Pool
└─► Instance/NIC receives IPv4 + IPv6 via DHCPv6 Stateful
Three layers are required for an Instance to have IPv6:
| Layer | Who does it | Condition |
|---|---|---|
| General-type VPC | FPT Cloud (at your request) | stackMode = dual, pre-configured |
| Subnet | You (Tenant User) | Tick Enable IPv6 dual-stack when creating the Subnet |
| Instance/NIC | You (Tenant User) | Created in a dual-stack subnet → receives IPv6 via DHCPv6 |
Key concepts
stackMode
A VPC attribute that defines which IP address types are supported:
| Value | Meaning |
|---|---|
ipv4 | VPC supports IPv4 only (legacy default) |
dual | VPC supports both IPv4 and IPv6 |
stackMode is set when the VPC is created and cannot be changed afterward.
IPv6 Parent Pool (/64)
When FPT Cloud configures a General-type VPC with dual-stack, the system attaches an IPv6 Parent Pool to the VPC. This pool is a large IPv6 address block (for example, 2401:db00:1100:a00::/64) from which Subnets receive their /64 prefixes.
Subnet /64 prefix
Each dual-stack Subnet receives one /64 prefix from the VPC's Parent Pool. This is the basic unit of IPv6 subnetting — a single /64 holds roughly 18 quintillion addresses.
- The /64 is allocated automatically — you don't choose it manually
- IPv6 Gateway = the first address in the /64 (for example,
2401:db00:1100:a10::1) - IPv6 Mode is fixed at
DHCPv6 Stateful
DHCPv6 Stateful
The mechanism that automatically assigns IPv6 to an Instance's interface. When an Instance is created in a dual-stack subnet, DHCPv6 Stateful automatically assigns a unique IPv6 address to the NIC — no extra configuration needed.
Phase 1 scope
Phase 1 (Q2–Q3 2026) supports Dual-Stack for:
| Resource | IPv6 support | Who does it |
|---|---|---|
| General-type VPC | Dual-stack configured on request | FPT Cloud |
| Subnet | Enable IPv6 dual-stack at creation | Tenant User |
| Instance | Receives IPv6 automatically when created in a dual-stack subnet | Tenant User |
| NIC | Add an IPv6 NIC to a running Instance | Tenant User |
| Security Group | Create a rule with IP Type = IPv6 | Tenant User |
Not yet supported in Phase 1: Specific-type VPC, IPv6 Route Table, IPv6 Load Balancer, DNS AAAA record, and IPv6-only VPC.