It can't be done, IPv4 and IPv6 don't understand each other.

Communication between computers using IPv4 and IPv6 is a technical challenge due to the inherent incompatibility between the two protocols. However, to facilitate the transition and coexistence of IPv4 and IPv6 in mixed networks, there are several transition techniques and technologies.

We explain the most common transition techniques:

1. Dual Stack

This is the most direct technique and consists of configuring devices and servers to operate with both protocols, IPv4 and IPv6, simultaneously. Each device in a dual stack network can send and receive both IPv4 and IPv6 traffic, allowing communication with other devices regardless of the type of IP they use. This requires that operating systems, applications, and network devices support both protocols.

2. Tunnels

Tunnels are a solution that allows IPv6 packets to be encapsulated within IPv4 packets, thus allowing IPv6 traffic to be transported over an existing IPv4 infrastructure. This is useful for connecting islands of IPv6 networks across a predominantly IPv4 network. There are several tunneling methods, including:

• 6to4 tunnel: Uses a public IPv4 address as the anchor for the tunnel.
• Teredo Tunnel: Specially designed for clients behind NAT, it encapsulates IPv6 packets into UDP packets and sends them over IPv4.
• Configured tunnels: Requires manual configuration and is established between two specific points on the network.

3. Protocol Translation (NAT-PT and NAT64)

Network Address Translation for Protocols (NAT-PT) was one of the first techniques designed to translate communication between IPv4 and IPv6. Although it is obsolete and no longer recommended for new deployments, it introduced the concept of translation between the two protocols. NAT64 is a more modern approach that allows IPv6 devices to communicate with IPv4 services. Typically used in combination with DNS64, which synthesizes AAAA (IPv6) records for domain names that only have A (IPv4) records.

4. proxy

Using a proxy is another technique to facilitate communication between IPv4 and IPv6. A proxy server can accept IPv6 connections and then communicate with an IPv4 server on behalf of the client, or vice versa. This is particularly useful for web applications.

Considerations

The choice of technique depends on several factors, such as the existing network infrastructure, performance and security requirements, and the availability of resources to implement and maintain the chosen solution. The transition to IPv6 is inevitable in the long term, so planning for coexistence and eventual full migration to IPv6 is crucial for any organization.

Each of these solutions has its advantages and limitations, and the choice between them should be based on a detailed evaluation of the specific network needs and long-term objectives related to IPv6 adoption.