A detailed explanation of the difference between IPV6 and IPV4

summed up the following points:

　　First, the ability to extend routing and addressing

IPV6 the IP address from 32 to 128 bits to support a larger address space, estimating that there are 4*10^18 IPv6 addresses per square metre on the surface of the Earth, so that IP addresses will not run out in the foreseeable future.

The IPV6 address is encoded with a hierarchical hierarchy similar to CIDR, like a phone number. Simplifies routing and speeds up routing.

A "range" field is added to the multicast address so that multicast is not confined to subnets, but can span different subnets and different LANs.

　　Second, the simplification of the header format

Some redundant domains in the IPv 4 header format are discarded or listed as extension headers, which reduces the overhead of packet processing and header bandwidth. Although the IPV6 address is 4 times times the address of the IPV4. But the header is only twice times as big as it is.

　　Third, more support for optional options

IPV6 options are not placed in the header, but are placed in a separate extension head. If you do not specify that the router does not open processing extension headers. This greatly alters the routing performance. IPv6 relaxes the strict requirements for optional lengths (the total length of the IPV4 option is up to 40 bytes) and can be introduced with new options as needed. Many of the new features of IPV6 are provided by options, such as support for IP layer Security (IPSEC), support for Jumbogram, and support for IP layer roaming (MOBILE-IP).

　　Four, the function of the QoS

The internet can not only provide a variety of information, shorten people's distance. You can also do online entertainment. Online VOD is now being fired by businessmen in full swing, and most are only quasi-VOD level, and can only be achieved on the LAN, the Internet on the VOD is not ideal. The problem is that the IPV4 header has a field of service type, which is virtually ignored in the current router implementation. In the head of IPV6, there are two corresponding priority and stream segments that allow the datagram to be designated as an integral part of a flow of information and can be used to control the flow of those datagrams. For real-time communication, even if all packets are lost and kept constant, the priority is highest, and a newsgroup delay is not felt for a few seconds, so its priority is lower. IPV6 specifies that both fields must be implemented for each IPV6 node.

　　V. Authentication and Confidentiality

Added content on authentication, data consistency, and confidentiality in IPv6.