Network compatibility-IPv4 and IPv6 protocol conversion

We usually say that IPv4 and IPv6 are too compatible, which is essentially the protocol conversion between IPv4 and IPv6. Now we will discuss this topic. We will discuss about IPv4 and IPv6 protocol conversion technologies. First, let's take a look at their specific work methods and features.

IPv4 and IPv6 protocol conversion technology

The main idea is that when an IPv6 node communicates with an IPv4 node, an intermediate protocol must be used to convert the server, the main function of this protocol conversion server is to convert the network-layer protocol header between IPv4 and IPv6 protocols to adapt to the protocol type at the peer end.

Advantage: it can effectively solve the problem of intercommunication between IPv4 nodes and IPv6 nodes.

Disadvantage: All applications cannot be supported.

These application applications include:

① If an application that contains IP addresses, ports, and other information in the application layer protocol does not change the IP addresses in the higher-level packets, these applications will not work, such as FTP and STMP.

② Applications that are included in the application layer for authentication and encryption cannot work in this protocol conversion.

SOCKS64

One is to introduce SOCKS library in the client, which is called socks socksocksock). It is located between the application layer and socket, and replaces the socket API and DNS name resolution API at the application layer;

The other is SOCKS gateway, which is installed on IPv4 and IPv6 Dual-stack nodes. It is an enhanced SOCKS server that can implement any protocol combination of client C and destination D. When the SOCKS database on C initiates a request, the gateway generates a thread to relay the connection. SOCKS libraries and Gateways communicate with each other through the SOCKSSOCKSv5 protocol. Therefore, the connections between them are SOCKS-based connections, including not only business data but also control information; however, the connection between G and D is not changed and is a normal connection. The application on D does not know the existence of C. It thinks that the communication peer is G.

Transport Layer relay TransportRelay)

Similar to the working mechanism of SOCKS64, SOCKS64 performs protocol translation on the transport layer repeater, while SOCKS64 performs protocol translation at the network layer. Compared with SOCKS64, it can avoid problems caused by "IP group fragmentation" and "ICMP packet conversion", because each connection is a real IPv4 or IPv6 connection. However, the address cannot be converted because network application data contains network address information.

Application Layer Proxy gateway ALG)

ALG is short for Application Level Gateway. Like SOCKS64 and transport layer relay, ALG provides a dual-stack Gateway between IPv4 and IPv6 to provide the "protocol translation" function, that is, protocol conversion. However, ALG performs protocol translation at the application level. This effectively solves the problem of network address in the application, but ALG must write a separate ALG proxy for each business, and the client application must also support ALG proxy in different programs, poor flexibility. Obviously, this technology must be integrated with other transitional technologies for promotion.

Summary of IPv4 and IPv6 transition policies

Dual-stack and tunnel are mainstream

All transition technologies are implemented based on dual-stack.

Different transition strategies have different advantages and disadvantages and different application environments.

The evolution of networks will be a combination of various transitional Technologies

Analysis Based on the carrier's specific network conditions

There are many smooth IPv4 to IPv6 transition strategies proposed by different organizations or individuals. They all have their own advantages and disadvantages. Therefore, the best solution is to combine several of the Transition technologies to learn from each other and take into account the specific network facilities of operators and the cost factors, design a smooth transition solution suitable for the carrier's own development.