Comparison between IPv4 and IPv6 protocols (1)

1. Overview

The Internet has become an important part of information infrastructure in modern society. It plays an important role in the development of national economy and social progress. It has also become an important supporting environment for today's high-tech development, the success of the Internet is obvious to all.

The Internet protocol IPv4, which is widely used in the world, is the fourth version of Internet protocol. It has been around for 30 years. Technically, Although IPv4 has a brilliant performance in its past applications, it seems that there are many drawbacks.

The global development of WLAN, 2.5G, and 3G wireless mobile data networks accelerates the formation of Internet-centric communication models, the growth of mobile communication users is much faster than that of fixed network users, especially the rapid development of various mobile terminals with network functions, considering the need for personal multimedia communication in any form and in any place and anytime, the existing IPv4 address cannot meet the requirements of the network market for address space, end-to-end IP connection, service quality, network security, and mobile performance. Therefore, it is hoped that the new generation of IP protocol will solve the above problems.

IPv6 is based on this idea. It is short for "Internet Protocol version 6. IPv6 not only expands the IPv4 address space, but also reconsiders all aspects of the original IPv4 protocol and makes a lot of improvements. In addition to proposing a large number of addresses, IPv6 and IPv4 have a lot of work to achieve higher security and better manageability, and provide better support for QoS and Multicast Technologies. The following sections will discuss the differences between IPv6.

2. Comparison between IPv4 and IPv6 protocols

2.1 Header Format

As shown in table 1, the IPv4 header contains 20 bit + options and 13 fields, including 3 pointers.

Table 1 IPv4 Header

An IPv6 Header consists of a basic header and an extended header chain. The basic header is shown in table 2 and contains 40 BITs and 8 fields.

Table 2 IPv6 Header

The main differences between IPv4 and IPv6 Header formats are as follows.

IPv6 headers are composed of basic headers and extended header chains. This design allows you to easily add options to improve network performance, enhance security, or add new features.

2.1.1 fixed IPv6 basic header

The basic IPv6 Header is fixed to 40 BITs, which enables the router to speed up data packet processing and improve forwarding efficiency. This increases the overall network throughput and information transmission speed.

2.1.2 simplified basic IPv6 Header

The fields of the Shadow part in the IPv4 header are removed from the basic IPv6 Header. The segment offset, option, and fill fields are placed in the IPv6 extension header for processing.

Header Checksum is removed, and the intermediate Router does not perform packet verification. There are three reasons to remove this field: first, most layer-2 link layers have completed packet verification and error control, the reliability of the link layer makes it unnecessary for the layer-3 network layer to perform header verification. Second, the end-to-end Layer-4 Transport Layer Protocol also has the verification function to detect the wrong packet; third, header verification requires re-calculation at each hop as the TTL value changes, increasing the packet transmission latency.

Remove the IP Fragment-related fields from the basic IPv6 Header, so that the router does not need to partition the data packets. The fragment is performed by the source terminal device based on the MTU path discovery of the maximum transmission unit. In this way, IPv6 data packets can far exceed 64 kbit/s, and applications can use MTU for faster and more reliable data transmission.

2.1.3 Add a new traffic flag for the IPv6 Header

IPv6 not only saves service category fields in IPv4 headers, but also adds stream tag fields, allowing businesses to be further classified based on different data streams to achieve priority control and QoS Assurance, this greatly improves the quality of IPv6 services.