Service providers are obliged to move to IPv6 to accommodate new customers and content providers must ensure that their content is accessed regardless of the protocol of their customers use. Governments worldwide regulate the transition to IPv6 as well. This brings the challenge of ensuring that new IPv6 enabled devices are able to access any content - hosted on IPv4 or IPv6. NAT64 is a technology that provides the bridge between IPv6 and IPv4 by the transformation protocol that includes the other side.
NAT64 is the translation from IPv6 to IPv4 on the basis of a pre-assigned / 96 prefix that is carried in the packet destination IPv6 address. Last 32 bits of the IPv6 address are the address
IPv4 IPv4 destination host. As traffic passes through the NAT64 device, it looks for the prefix match - if the match is found, the device knows that the destination IPv4 host and needs translation. Unlike the good old NAT devices, NAT64 devices must perform the transformation protocol - the creation of an IPv4 header based on the information in the IPv6 header. There are additional requirements to ensure that two disparate systems can talk to each other as the ICMP translation and translation traditional applications that integrate information in layer 3/4 packet (eg, FTP, SIP, etc.).
Now the question is - how to initiate the connection IPv6 host knows the destination address? This space is filled by the DNS64 device. Whenever DNS64 device receives a request (AAAA) to resolve a name - it first tries to find the IPv6 address. If the address is found, it is returned to the host, but no IPv6 address - DNS64 device obtains the IPv4 address prepends the prefix and returns 96-bit preconfigured host . The following diagram shows the sequence of events when an IPv6 host attempts to connect with an IPv4 server.
In the early stages of transition to IPv6 content providers are mainly provide access to Web content hosted on IPv4 servers. In such scenarios SLB64 offer advantages over technology NAT64 pure. SLB64 is balancing server load by exposing the IPv6 connection points for IPv4 servers. - So SLB64 not only provide translation devices but also provide other benefits that come with advanced ADCs like NetScaler
There are many critics of NAT but there is no denying that NAT has been used for years and will not go anywhere soon. For IPv6 transition, it is becoming a technology very strong.
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