Figures 1 and 2 compare the IPv4 and IPv6 headers. In the IPv4 header, there are fields shaded in yellow (version, source I.P. address and destination I.P. address) that were kept in IPv 6.  There are fields shaded in green (type of service, total length, time to live and protocol) that were renamed or repositioned in IPv6 and the fields shaded in gray were dropped in IPv6. The IPv6 header has a new field called flow label. The advantages of IPv6 are listed in Figure 3. These advantages include: better routing efficiency for performance and forwarding-rate scalability; no requirement for processing checksums; simplified and more efficient extension header mechanisms (as opposed to the IPv4 Options field); and a Flow Label field for per-flow processing with no need to open the transport inner packet to identify the various traffic flows.