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Top1. Introduction
The IPv4 address space is quickly being exhausted, and there is a great need for a new protocol to overcome the lack of address space. It is for this reason that the new IPv6 protocol has been introduced, giving a larger address pool as it uses 128-bit address sizes. This means that there are many more addresses available than there are Internet-connected devices which mean that IPv6 is future-proof and allows for significant growth in internet technology. A further advantage is that there is no requirement for Network Address Translator (NAT) because each device is assigned a unique IP address. IPv6 has been designed with new features such as auto-configuration of addresses, improved the security, better quality of service (QoS) and a new header format (Zhou, 2014). It is due to this scarcity of address space that organisations are beginning the migration to IPv6 within their networks.
IPv6 and IPv4 are incompatible protocols, which means that interconnection between protocols is not available to network users, prohibiting them from connecting across networks. Therefore there is a requirement to use a transition mechanism(s) to allow for smooth migration and to allow IPv6 hosts to pass through IPv4 networks or connect with IPv4 hosts. The designers of IPv6 in the original specification (RFC 1752) defined the following transition criteria:
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It is simple to upgrade IPv4 hosts to IPv6 without disruption and can these be done without an upgrade of other routers or hosts which may be on the network?
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There are no dependencies which exist on other hosts or routing infrastructure when adding new IPv6 hosts.
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Both IPv4 and IPv6 addresses can be used in tandem without the need to upgrade all nodes at the same time.
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Upgrading IPv4 infrastructure to IPv6 requires little preparation, much like with deploying new IPv6 nodes.
There are a number of transition technologies which have been proposed and are widely use today such as dual stack and tunnel mechanisms. Due to the Internet services which widely use IPv4, it is important to know that the transition from the previous protocol to IPv6 may take years to complete, and that means both protocols will be working together (Wu et al., 2013).
It can be said that changes in networks such as an upgrade to IPv6 may cause issues and may come at a high risk to an organisation. Network security is a very important aspect that should be looked at before migrating to IPv6. Moreover, most network security tools are designed and implemented to secure the IPv4 only. The scarcity of IPv6 related tools for network security analysis, as well as the lack of trained professionals, will lead to slow response times against network attacks.
The aim of this paper is to investigate the dual stack and tunnelling technologies while also looking at security risks of IPv6 and transition technologies. This will be accomplished by looking at both dual stack and tunnelling mechanisms in section 3, the translation security issues in section 4, the implementation and analysis of dual stack and tunnelling mechanisms along with IPv6 attacks in section 5, the performance analysis of various network scenarios in section 6 and final thoughts and conclusion in section 7.
Top2. Background
This section examines the research which has already been conducted in IPv6 and looks at where further research is required. Despite the immature nature of IPv6, it has become a widely researched topic; however, one may say that there are still gaps in knowledge which have been generated by this research. In trying to accomplish the objectives of the research, the first element requires the IPv6 transition mechanisms to be defined, (Hou et al., 2010) an explanation for the scarcity of address spaces in IPv4 and extensive growth of the Internet in the past couple of years. Many kinds of systems and servers over the Internet have been developed based on IPv6 such as online shopping, Internet banking and trading stocks (Altaher et al., 2011; Albkerat and Issac, 2014).