Protocol transitions are challenging and are not easy especially when we talk about the transition of Internet Protocol version 4 to Internet Protocol version 6. This might be a bit simple in case of small network but really challenging in huge networks. This book shows research on a number of transition methods of IPv6 and problems associated with these existing transition mechanisms. Practical work on Tunnel Broker mechanism has been performed and experimented during this research. IPv6 performance was checked on a DHCPv6 server when it gives automatic IPv6 addresses to the clients, DHCPv6 clients when they receive IPv6 addresses from the server and at the tunnel broker when it creates a tunnel in the tunnel server for the client and sending relevant information back. Packet filtering has been done with IPv4 and IPv6.