Network performance issues in IP transition phase

IPv4 is a foundation of Internet communications. Designed many years ago the protocol is inadequate to modern networks. New sixth version is replacing the older one. It is often repeated that IPv6 was designated to solve some performance problems. This statement is true only to some extent. IPv6 deployment (especially in the transition phase) will have large impact, not always positive on many aspects of Internet services: network performance, data security, economy. As number of IPv6 networks grow, understanding of performance issues becomes more important. The paper attempts to present comprehensive survey on positive and negative IPv6 impact on performance with a special emphasis on IPv4 to IPv6 transition phase. The survey is accompanied by brief analysis of third party test results.