Method and device for achieving address translation

The invention discloses a method and device for achieving address translation. The method comprises the steps as follows: IP address information of a fixed outlet IP service is set aiming at each NATin a cluster; the NAT detects that the message is an IP tunnel message of the fixed outlet IP service accessing a public network, and the IP tunnel message finds the IP address information of the fixed outlet IP service set by the NAT; source address translation is performed on the IP tunnel message and a session is built by using the found IP address information of the fixed outlet IP service, and the message after being subjected to NAT translation is sent to an NSW. 本申请公开了种实现地址转换的方法及装置，所述方法包括：针对集群中的每个NAT，设置固定出口IP业务的IP地址信息；NAT检测出报文为访问公网的固定出口IP业务的IP隧道报文，且该IP隧道报文找到NAT设置的固定出口IP业务的IP地址信息；利用找到的固定出口IP业务的IP地址信息对该IP隧道报文进行源地址转换并建立session，发送经过NAT转换的报文给NSW。