改进DNS64域名解析机制在IVI过渡方案中的应用

Application of DNS64 Mechanism in IVI Transition

IVI过渡方案是IPv4/IPv6网络过渡时期实现两种不同协议网络互联互通的重要机制,而对IVI DNS64域名解析机制的设计和部署是IVI过渡方案中的重要研究课题.本文针对IVI过渡方案中现有的域名解析机制存在的IPv6主机访问IPv4环境中双栈服务器时DNS64代理对双栈服务器的合成AAAA类型记录和真实AAAA类型记录的选择而造成的无法访问的问题和IPv6环境下的双栈主机查询IPv4服务器A类型记录却得到合成AAAA类型记录应答等缺陷,提出一种改进的域名解析机制,能够有效解决现有解析机制存在的缺陷,从而完善IVI DNS64域名解析机制.仿真结果表明,改进后的机制可使得IPv6环境中的主机通过IVI DNS64代理来共享IPv4环境中的DNS服务,同时避免了原方案中存在的问题.改进的IVI DNS64机制已应用在CNGI-CERNET2网络的实际部署中.

The IVI is a translation mechanism for the IPv4-IPv6 communications during the period of IPv4/IPv6 coexistence and tran- sition. And it is an important research issue of designing and deploying the domain name resolution function based on IVI DNS64 mechanism. Defects that are exposed in the native DNS64 mechanism under complex conditions, include that IVI6 （ i } hosts fail to communicate to the dual-stack server as well as that dual-stack hosts fail to receive the right response when they send A type request to IPv4 DNS in IPv6 environment. In order to improve the domain name resolution mechanism of IVI DNS64, this article proposes a modified version of DNS64 mechanism, which can effectively solve the existing defects in the native DNS64. The simulation shows that hosts in IPv6 can share the DNS in IPv4 through implementing the modified version of DNS64 mechanism in the IVI DNS64 cli- ent. The modified version of DNS64 mechanism is applied in the deployment of CNGI-CERNET2.