Removal of these fields makes processing of IPv6 header faster andimproves overallrouter performance (Ferry, 2003). Figure 1.1 shows the header structureof IPv4 andIPv6. Integrated Internet Protocol security (IPsec): Initially, Internet Protocol was not designed with security in mind (Kumar et al., 2011) therefore data was not protected in the IP layer.
When data security became a major issue, different security techniques were developed but implemented in the upper layers of the protocol suite to protect data from unauthorized access. An example of this is the Secure Socket Layer (SSL) used to protect web data in the application layer. Besides SSL, other security technologies exist for the same purpose. The use of different security technologies in the upper layers for the same purpose means that security functionality is duplicated.
To overcome this problem, a new security layer called IPsec was builtinto IPv6 toprotect packets in the IP layer. IPsec protects packets by providingintegrity,confidentiality, authentication and non–repudiation (Kent et al, 1998).Although IPsec can also be used in IPv4, it is optional but not mandatory as inIPv6.
Also, when IPsec is deployed together with NAT, packet protection becomesdifficult. With NAT the IP address and the port number of a packet must bechanged and hence complete packet protection cannot be guaranteed. This can alsolead to a compromise in end to end security deployment. In IPv6, the use of NATis eliminated and so complete end to end security can be deployed without thisissue. Also when the IP layer is protected, there is no need to protect packetsin upper layers that might lead to duplicated security functionality (Blanchet,2009). Improvements in IPv6 packet structure makes it different from the packetstructure of IPv4 and this means that routing IPv6 traffic will not besupported by older routing protocols used in IPv4 (Genkov, 2011).
Also,considering the importance given to network scalability and reliability duringrouting protocol implementation, development of dynamic routing protocolssupported by IPv6 became a necessity.