#4) IPv6 contains simplified Header Structures leading to faster routing as compared to IPv4
The present IP uses a Datagram service to transfer packets of data between point to point using routers. The IPv4 packet header structure contains 20 bytes of data, such that it contains within the header, all possible options thereby forcing intermediate routers to check whether these options exist and if they do, process them before forwarding them. In the IPv4 packet header, these options have a certain maximum permitted size.
Challenge to IPv4
The IPv4 header has two main problems that are instrumental in slowing down throughput – each packet must be processed and checksum computed, and each router that processes a packet must process the option field. This can cause a gradual degradation in performance during the forwarding of the IPv4 packets.
How does IPv6 provide a solution?
When compared to IPv4, IPv6 has a much simpler packet header structure, which is essentially designed to minimize the time and efforts that go in to header processing. This has been achieved by moving the optional fields as well as the nonessential fields to the extension headers that are placed only after the IPv6 header. Consequently, the IPv6 headers are processed more efficiently at the intermediate routers without having to parse through headers or recompute network-layer checksums or even fragment and reassemble packets. This efficiency allows for reduced processing overhead for routers, making hardware less complex and allowing for packets to be processed much faster.
Another feature of the IPv6 header structure is that the extension header allows for more flexible protocol inclusions than what IPv4 does. In contrast, IPv6 extension headers have no such restriction on the maximum size. They can be expanded to accommodate whatever extension data is thought necessary for efficient IPv6 communication. In fact, a typical IPv6 packet contains no extension header and only if intermediate routers or the destination require some special handling, will the host sending the packets add one or more extension headers depending on the requirement. This new extension header makes IPv6 fully equipped to support any future need or capabilities.