1. Introduction:
The Internet is growing day by day around the world. Different types of devices are becoming the part of the Internet daily. Some of them are fixed and others are movable. Movable devices (such as Laptop and iPhone) can easily move anywhere in the network. They are required IP address for communication to each other over the network. Internet Protocol (IP) is the most widely used routed protocol over the Internet [1]. There are two versions of IP: IPv4 and IPv6. IPv4 protocol is a 32-bit addressing scheme. It was introduced in 1981. Due to its shortage addresses, IPv6 protocol was introduced by the Internet Engineering Task Force (IETF) in 1990 [2]. IPv6 is a 128-bit addressing scheme. IPv6 is the next generation internet protocol [3]. It will gradually replace with IPv4 in all over the world. IPv4 is comparatively easy to configure but IPv6 is more complicated due to its nature of complex addresses [4]. However, IPv6 has more advantages over IPv4 in terms of header format simplification, efficient routing, security, QoS and route optimized mobility [5-6]. IPv6 provides QoS through the fields of flow label and traffic class. IPv6 header consists of 8 fields and 40 bytes in length as shown in Fig. 1 whereas IPv4 header consists of 13 fields and 20 bytes as shown in Fig. 2. There are millions of devices around the world which are using IPv4; therefore, it is not easy to transit at once. A study report tells that after twenty five years, it replaced