Detailed explanation of IPv6 theory and concept

Preface ：

At present, our country has also begun to vigorously promote the use of ipv6, And Tencent cloud 、 Alibaba cloud and other major manufacturers are also on the shelves ipv6 Services related to , If you are interested, you can go to the official website of the cloud manufacturer to learn about ,ipv6 The emergence of ipv4 The problem of address exhaustion , however ipv6 The network is not perfect yet , Through this article , It gives you a general idea of ipv6 Principle , Convenient for future use , Without further ado , Let's get started. .

IPV6 Introduction and how the address is expressed or written ：

IPv6 Is the sixth edition of the Internet Protocol ; At first it was IETF Of IPng The winner in the selection process is called the Internet new generation Internet protocol (IPng),IPv6 It is the second version of internet protocol that is officially and widely used .

ipv4ipv5ipv6

IPV4： Existing standards IPv4 Only about 40 Billion (4×109) Network addresses , At present, the mainstream three-layer communication address .

IPv5： No IPv4 Inheritance , Is an experimental stream oriented data flow protocol , Used to sound , Images, etc .

IPv6： Support 3.4 ×10^38 individual , This is equivalent to... Per square inch of earth 4.3×1020 Address .

IPv6 Address representation

by 128 Bit length , But usually writing 8 Group , Each group is in the form of four hexadecimal numbers

for example ：2003:0bd8:75c3:08d3:1319:8e2a:0371:7433/120

If all four numbers in one group are zero , Can be omitted .

for example ：2003:0bd8:75c3:08d3:0000:8e2a:0371:7433

2003:0bd8:75c3:08d3::8e2a:0371:7433

If more than two colons appear because of ellipsis , It can be compressed into a , But this zero compression can only occur once in an address .

for example ：

2003:0bd8:0000:0000:0000:8e2a:0371:7433

2003:0b08::8e2a:0371:7433

2003:0bd8:0000:0000:0000:8e2a:0000:7433

2003:0bd8::8e2a:0000:7433

If IP All addresses are 0 Words , You can use two colons instead of .

for example ：

::

If ipv6 Address of the 8 In the group , front 7 All the patients in group A were normal 0, And the last group 0 start , Then you can omit the beginning , But don't omit the ending and the middle 0.

for example ：

0000:0000:0000:0000:0000:0000:0000:0433

::433

0000:0000:0000:0000:0000:0000:0000:0403

::403

0000:0000:0000:0000:0000:0000:0000:0400

::400

IPv4 The address can be converted to IPv6 Format 128-32

Ipv4 yes 8 position 2 Into the system for 1 Group ,ipv4 All in all 4 Group , and ipv6 All in all 8 Group , Each group of 16 position , that ipv4 Convert to ipv6, The first one can put the front 6 The groups are all 0, Replace with a colon , Then left 2 Group , In the process of transformation .

for example ：135.75.43.52172.3.5.111010110000000011

::874b:2b34::ac03:050b

IPV6 Header format ：

Ipv6 A detailed explanation of the headlines ：

Ipv6 In the newspaper Traffic level ： amount to ipv4 In the newspaper Type of Service（ Service type ）; Which type of high priority forwarding , That low will be forwarded later .

Stream tags ： In the three-layer network layer , Every packet , Make corresponding labels , Carry out segmented data transmission processing ; Be similar to ipv4 Identification in the header .

Payload length ： In the header transmission data , The maximum transmission unit is 1500 byte , Remove the basic header 40 Bytes and extended headers , Its payload length is 1500-40; If there is an extended header , It also needs to be included .

The next headline ： Be similar to ipv4 The protocol in the header ; The protocol that encapsulates the next header is that .

Jump limit ：ipv6 The packet is in the router , Jump restrictions to be followed for conversion ; Be similar to ipv4 The lifetime in the header .

notes ： To achieve ipv4 Functions in the header , You can extend the header , Add .

IPV6 Address type of

①： Unicast address Point to point transmission

②： Multicast address

③： Anycast address

IPV6 The subnet partition of

①： Prefix

ipv6 in , There is no concept of subnet mask and network segment , If the broadcast domain is divided , Similar to the network bit and host bit based approach , The network bit length is prefixed . 128=64+64

②： host ID

How to identify the host bit

Prefix / host ID

And different operating systems , Subnets are represented in different ways

Windows China and Israel % Express

Pictured above , The prefix for 8 position （ With 2 It's expressed in hexadecimal ）, That means as long as it is fe At the beginning ipv6 The address is in the same subnet ; And the rest of the 120 All bits are hosts ID.

IPV6 Special address

IPV6 Uncertain address ：::/128

IPV6 Local return address ：::1/128

IPV6 Multicast address ：FF00::/8

IPV6 Local link address ：fe80::/10 For a single link , For automatic configuration 、 Adjacent machine discovery, etc , Routers don't forward （ amount to IPV4 Miscellaneous address 169.254.xxx.xxx）

IPV6 Private network address ：FC00:: - FD00::1/128

Global unicast address assigned ： The third place must be 1 Default prefix 64 Further subnet division can be done

With 2000 start 2000:: 2001、2002 Reserve special unicast

2003 Start normal global unicast address

ipv6 Address calculation tool site ：

http://www.gestioip.net/cgi-bin/subnet_calculator.cgi

Add... To the router IPV6 Address method

Global mode ： Turn on IPV6 Addressing function ipv6 unicast-routing

Interface mode ： To configure IPV6 Address ipv6 add xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx/xxx （IPV6 Address / Prefix number ）

ipv4 The defects of

iPV4 The address is exhausted

iPV4 Address one uses private address translation , This is the solution IP An expedient for address shortage , It is not conducive to ensuring network service quality and network security , Affect the long-term development of China's Internet ;

IPv6 The constraints of

1： The lack of IPv6 information resources ;

2： Current situation of network security protection , Firewall management control , Restricted IPv6 Development . What's important is ：IPv4 and IPv6 Theoretically incompatible , Therefore, the interconnection technology needs to be developed .

3： Network operator related development and constraints