What are IPV4 and IPV6?

First, write it in front

Binary

Binary only has 0 or 1, and every 2 will carry over. The comparison table is as follows

For example:
255=128=64+32+16+8+4+2+1
So the binary of 255 in decimal is eight 1s: 11111111

IPV4 address introduction

IPV4 address is composed of 4 groups of 8-bit binary, each group's decimal number range is 0 to 255
IP: network number + host number
IP addresses are divided into A, B, C,Classes D, E, D and E are special classes

In order to solve the unreasonable IP allocation caused by simple classification, the subnet mask was born
The subnet mask is actually used to distinguish the network number and the host number, and can be used to indicate that the following four IP addresses belong to the same network
> First convert the decimal to binary, use 1 to lock the same number of digits, and use 0 to represent different digits

The subnet mask is as follows:

Then convert the binary number to decimal, so the subnet mask is 255.255.255.252
We can clearly know the network number by putting the subnet mask and ip address togetherand host number boundaries

CIRD

There are several 1s in the subnet mask, so we can directly use '/(number of 1)' to represent the subnet mask
That is to say, we can use 192.168.0.0/30 to represent the above 4host numbers are in the same network

Second, the difference between IPV4 and IPV6

hex

Hexadecimal and decimal conversion

The difference between IPV4 and IPV6

1. Performance

Compared with IPv4, IPv6 increases the address length from 32 bits to 128 bits, which can support more address requirements.Moreover, the coding of IPv6 addresses adopts a hierarchical hierarchical structure similar to CIDR, which simplifies routing and speeds up routing.

2. Simplification of header format

IPv4 has a variable length of 20 to 60 bytes according to the IP options provided; while IPv6 has a fixed length of 40 bytes, and the header is simpler than IPv4.Also, IPv4 headers may come with various options, but IPv6 headers have no options, but add additional extension headers (optional, which contain hop-by-hop extensions, routes, fragments, and destinations, etc.), greatly reducing packet processingand header bandwidth overhead.

Compared with IPV4, IPV6 changes DiffServ toTraffic class, the total length is changed to the payload length, the TTL is changed to the hop limit, and the protocol is changed to the next header
The first 64 bits of IPV6 are the network part, and the last 64 bits are the interface ID

3. Cybersecurity

For IPv4, Internet Security Protocol (IPsec) is optional, but not necessarily free, and some require paid support; but for IPv6, Internet Security Protocol is required.Additionally, things like authentication, data consistency, and confidentiality were added to IPv6.
In this way, the design of IPV6 does consider many security issues, but there are still many security issues in practical applications, and it is not clear which is more secure than which one

4. Address Type