IPv6 test based on NAT-PT (1)

NAT-PT is a network address converter with protocol conversion. By modifying the protocol header, you can change the network address so that IPv4 nodes and IPv6 nodes can communicate with each other. Different from some tunneling technologies, NAT-PT only needs to be enabled on the network conversion device that is interconnected between IPv4 and IPv6, the purpose of protocol conversion is to achieve the conversion between IPv4 and IPv6 protocol headers, address Translation aims to allow IPv4 and IPv6 hosts to recognize each other. In addition, by combining with the Application Layer Gateway ALG), The NAT-PT realizes the communication between the host that only installs IPv6 and the application that only installs IPv4 host.
At the same time, the NAT-PT will SIITStateless IP/ICMP Translation) protocol conversion technology and IPv4 network dynamic address Translation technology NAT) combined. It uses the work mechanism of SIIT technology and the NAT technology of traditional IPv4 to dynamically access IPv6 nodes of IPv4 nodes and allocate IPv4 addresses, it effectively solves the problem of limited size of global IPv4 address pool in SIIT technology.
SIIT Technology
Stateless IP/ICMP Translation technology Stateless IP/ICMP Translation, SIIT) is a technology for protocol conversion of IP/ICMP packets, it does not record the status of a stream Stateless ). In the SIIT network, IPv6 nodes must be configured in the format of: FFFF: 0: W. x.Y. IPv4 address of Z, where W. x.Y. Z is the address of an IPv4 node in an IPv4 network. When an IPv6 node accesses an IPv4 node, it uses the ing address: FFFF: 0: W. x.Y. Z to represent IPv4 nodes.

 
Figure 1 SIIT Principle

Set IPv4 host AIPv4 address to 100.0.0.1), IPv6 host B address to: FFFF: 0: W. x.Y. Z IPv4 address, and W. x.Y. Z is the global IPv4 unicast address set to 1.1.1.1 ).
1. SIIT Principle Analysis
1) IPv4 to IPv6 Address Header Conversion
Assume that A wants to access B: When the packet sent by A to access B reaches the SIIT protocol converter, the destination address of the packet is B's low 32 bits. Here it is 1.1.1.1 ), SIIT determines that this address belongs to the IPv4 address space of its managed IPV6-Only node and is set to 1.1.1.1 ~ 1.1.1.254), the IPv4 → IPv6 Protocol packet header is converted, the source address is converted to the IPv4 ing address, and the destination address is converted to the IPv4 translation address: FFFF: 0: W. x.Y. z. Then, the packet is sent to host B. That is, the source address 100.0.0.1 →: FFFF: 0: 100.0.0.1, the destination address 1.1.1.1 →: FFFF: 0: 1.1.1.1.
2) Translation of IPv6 to IPv4 address Headers
Now suppose B wants to access A: When B sends A packet to access A to the SIIT protocol converter, the source address of the packet is B's translation address: FFFF: 0: 1.1.1.1 ), the destination address is the ing address of A: FFFF: 0: 100.0.0.1). If SIIT determines that the destination address is an IPv4 ing address, it performs Protocol packet header conversion from IPv6 to IPv4, the conversion result is: Source Address: FFFF: 0: 1.1.1.1 → 1.1.1.1, Destination Address: FFFF: 0: 100.0.0.1 → 100.0.0.1.