The actual transition from IPv4 to IPv6 requires network administrators to become aware of the next generation protocol and the associated risk problems.Due to the scale and complexity of current internet architecture how to protect from the existing investment and reduce the negative influence to users and service providers during the transition from IPv4 to IPv6 is a very important future topic for the advanced version of an internet architecture.This paper summarizes and compares the IPv6 transition mechanism methods like Dual Stack,Tunneling issues like IPv6 Automatic tunneling and manually configured tunneling considerations, the IPv6 transition scenarios,IPv6 transition security problems,highlights IPv6 and IPv4 threat review with automatic tunneling and configuration tunneling considerations.In this paper we have proposed a transitional threat model for automatic tunneling and a configuration tunneling that could be followed by the University of Mysore(UoM),to estimate automatic tunneling and a manually configured tunneling threat review issues.Furthermore,there are different tunneling mechanisms such as IPv6 over IPv4 GRE Tunnel,Tunnel broker,Automatic IPv4 Compatible Tunnel and Automatic 6 to 4 Tunnel and also outlines many of the common known threats against IPv6 and then it compares and contrast how these threats are similar ones,might affect an IPv6 network.