Understanding IPv6 network protocols

The driving force of technological development is the constant demand of people. With the increasing use of the Internet, the current network protocol version is no longer able to meet the needs of the times. Inevitably, we will launch a new generation of IPv6 network protocols that are more complete and have diverse functions. The inevitable elimination of IPv4 indicates that the development of the network will usher in its first innovation.

IPv6 is short for "Internet Protocol Version 6" and also known as the next-generation Internet Protocol. It is a new ipprotocol designed by IETF to replace the current IPv4 Protocol.

IPv6 is proposed to solve some problems and deficiencies in IPv4, and it also proposes improvements in many aspects, such as routing and automatic configuration. After a long period of coexistence between IPv4 and IPv6, IPv6 will eventually completely replace IPv4 in the dominant position on the Internet. Compared with IPv4, IPv6 has the following features. These features can also be called IPv6 advantages: Simplified headers and flexible extensions; hierarchical address structures; plug-and-play connection methods; authentication and encryption at the network layer, satisfying service quality, and better support for mobile communication.

1. Simplified headers and flexible extensions

IPv6 simplifies data headers to reduce processor overhead and save network bandwidth. The IPv6 network protocol Header consists of a basic Header and multiple Extension headers. The basic Header has a fixed length of 40 bytes) and stores the information to be processed by all routers. Because most packets on the Internet are simply forwarded by the router, a Fixed Header Length helps speed up routing. The IPv4 header has 15 fields, while IPv6 only has 8 fields. The IPv4 header length is specified by the IHL domain, while IPv6 is fixed to 40 bytes. This makes it easier for the router to process IPv6 headers.

At the same time, IPv6 also defines a variety of extension headers, which makes IPv6 extremely flexible, can provide strong support for a variety of applications, and at the same time to support new applications in the future. These headers are placed between the IPv6 Header and the upper header, each of which can be confirmed by a unique "next Header" value.

Besides the path-by-path option header, it carries the information that must be processed by each node in the transmission path, the extended header can be processed only when it reaches the target node specified in the IPv6 Header (each specified target node is used for Multi-Point broadcasting ). There, the standard decoding method used in the next header field of IPv6 calls the corresponding module to process the first extended header (if there is no extended header, the upper-layer header is processed ). The content and semantics of each extended header determine whether to process the next header. Therefore, the Extended Headers must be processed in the order they appear in the package. The implementation of a complete IPv6 network protocol includes the following implementation of the extension header: one-by-one path segment option header, destination option header, Route Header, segment header, identity authentication header, the payload Security Encapsulation Header and the final destination header.

2. Hierarchical address Structure

IPv6 expands the length of an existing IP Address by four times, from 32-bit IPv4 to 128-bit, to support a large number of network nodes. In this way, the total number of IPv6 addresses is about 3.4*10E38. On the earth's surface, 6.5*10E23 addresses per square meter will be obtained. IPv6 supports more levels of address layers. IPv6 designers divide IPv6 address spaces according to different address prefixes and adopt a hierarchical address structure, this helps the backbone network router to quickly forward data packets.

IPv6 defines three different address types. They are: Unicast Address, Multicast Address, and Anycast Address ). All types of IPv6 addresses belong to Interface) rather than node ).

An IPv6 spof address is assigned to an interface, and an interface can only belong to a specific node, therefore, the single point transfer address of any interface of a node can be used to indicate the node.

The spof address in IPv6 is continuous. The bitwise masked address is similar to the IPv4 address with CIDRclassless inter domain router. An identifier only identifies one interface. There are multiple single point transfer addresses in the IPv6 network protocol, it includes the Global provider-based spof address, geographical location-based spof address, NSAP address, IPX address, local node address, local link address, and IPv4-compatible host address.

A multi-point transfer address is an address identifier that corresponds to multiple interfaces. Generally, it belongs to different nodes ). An IPv6 multicast address is used to represent a group of nodes. A node may belong to several multi-point transfer addresses. Multicast over the Internet was developed with the emergence of class D IPv4 addresses in 1988. This function is widely used by multimedia applications. It requires the transmission from one node to multiple nodes. The RFC-2373 gives a more detailed description of the multi-point transfer address, and gives a series of pre-defined multi-point transfer address.

The transfer address of any point is also a condition where an identifier corresponds to multiple interfaces. If a packet is required to be sent to an arbitrary point transfer address, it will be sent to the nearest one in the group of interfaces identified by this address based on the distance measurement method of the routing protocol ). Any point transfer address is divided from the single point transfer address space, so it can use any form that represents the single point transfer address. Syntactically, there is no difference between it and the spof address. When a single point transfer address is directed to more than one interface, the address becomes a transfer address of any point and is explicitly specified by the IPv6 network protocol. When a user sends a data packet to this arbitrary point transfer address, the server closest to the user will respond to the user. This is of great benefit to network users who often move and change.