Adopting Public IPv6 for Three-Tier Web Applications

As public IPv4 addresses are nearly full, the cost and effort of maintaining IPv4 public IPs for your workloads is only increasing. IPv6 public addresses can solve this problem. IPv6 public addresses are more plentiful and cheaper to purchase. This also improves compatibility with all IPv6-based clients, such as IoT devices.

Application Gateways now support dual-stack configurations, allowing you to use IPv6 addresses as the frontend for your web applications in Azure. This change only affects the frontend, and you do not need to allocate internal IPv6 address space to use it, and you can continue to use IPv4 frontends if needed.

This article simplifies the process of exposing your current web application to the Internet over IPv6 while continuing to run IPv4 on Azure Virtual Machines. This scenario is ideal for users who require IPv6 exposure but do not need to fully adopt IPv6 within Azure.

Existing solutions

The entire environment operates on IPv4 and consists of a single virtual network with four subnets.

AppGwSubnet

Includes an application gateway that acts as a front-end to load balance traffic to the web servers in the WebSubnet.

Web subnet

It contains two IIS web servers that forward traffic to the AppServer internal load balancer VIP in the AppSubnet, which distributes the load between the AppServers.

App Subnet

It contains two AppServers that forward traffic to the database internal load balancer VIP in the DataSubnet, which distributes the load between the database servers.

Data subnet

It includes two database servers using master/slave replication that respond to queries from the AppServer.

Step-by-step adoption process

1. Develop an IPv6 address plan and update your virtual networks with the IPv6 address space.

1st. reference Conceptual Plan for IPv6 Networking Guidelines for planning your IPv6 networking strategy. For IPv6, it is best to deploy /56 prefixes for virtual networks and /64 prefixes for subnets.

Conceptual Planning for IPv6 Networking – Azure Architecture Center | Microsoft Learn

1b. Add IPv6 addresses to the subnets connected to the virtual network and application gateway to support dual-stack (IPv4 and IPv6) configurations.

Add IPv6 to virtual networks and subnets

memo: If your subnet currently hosts Application Gateway SKU V1, you must create a new subnet to deploy Dual-Stack Application Gateway. However, if you use Application Gateway SKU V2, you can deploy Dual-Stack Application Gateway within the same subnet.

2. Distribute something new Dual stack Application Gateway New IPv4 and IPv6 frontend IP configurations

2a. Set up a new application gateway with dual stack support to handle both IPv4 and IPv6 traffic. Assign new public frontend IP addresses for both IPv4 and IPv6 during creation.

Creating a Dual Stack Application Gateway

Generate IPv4 and IPv6 frontend IPs

2. Ensure that the new Dual-Stack Application Gateway is configured with the same settings as the original, including a listener with a TLS certificate (for HTTPS/TLS offload), a routing rule with backend HTTP settings (including the certificate for end-to-end TLS), a backend pool, and a health probe.

2c. Both IPv4 and IPv6 frontend IPs use the same web application backend pool. Make sure the backend pool is healthy before proceeding to the next step.

3. Update your public DNS records

3rd. Update the DNS ‘A’ record to point to the new dual-stack public IPv4 frontend IP address. Similarly, update the DNS ‘AAAA’ record to point to the new dual-stack public IPv6 frontend IP address.

Create Azure Public DNS Records

memo: If you are using Public DNS in Azure, follow the link above. If you are using another Public DNS service, make sure your records are updated accordingly.

4. The original application gateway is deprecated.

4a. once you are This can be done safely by updating DNS records and ensuring that the new IPv4 and IPv6 frontend IP addresses are working on the dual stack application gateway. delete Originally an IPv4-only application gateway.

Learn more:

Get the latest information on Azure products that support IPv6

https://learn.microsoft.com/azure/architecture/networking/guide/ipv6-ip-planning#configure-azure-ser…

What is IPv6 in Azure Virtual Network?

https://learn.microsoft.com/azure/virtual-network/ip-services/ipv6-overview