Internet Protocol version 6 (IPv6) is a new generation protocol that is designed to solve the issues which arises in IPv4. The introduction of IPv6 may pose additional security risks and give potential vulnerabilities in addition to those which are provided by IPv4. This paper analyzes the security vulnerabilities exist, network security improvements and implementation, and the distributed security policy in the IPv6. Hence, several security policies should be created to maintain the security for both IPv4 and IPv6.