Catalog

One 、IP Address

Two 、IP Address classification

  3、 ... and 、 Subnet partition

One 、IP Address

IPv4 from 32 Bit binary number composition , It is generally expressed in dotted decimal system
IPv4 By 32 Bit binary number composition , Divided into four groups , Group 8 . example   Such as :11000000.10101000.00000000.00000010
For ease of configuration, it is usually expressed in dotted decimal form, such as :192.168.0.2 255.255.255.0
IPv6 from 128 A composition , Generally separated by colons , Hexadecimal representation
IPv4 The address consists of two parts :
Network part (NETWORK) The host part of the （HOST)192.168.1.132
Network part (192.168.1) The host part of the (132)192.168.1.0（ network address ）192.168-1.255（ radio broadcast ）
IPvA Private network address and public network address :
Public network address （ Hereinafter referred to as the public network address ） It refers to the only in the world on the Internet IP Address .2019 year 11 month 26 Japan , It is a memorable day in the era of human Internet , almost 43 One hundred million IPv4 Address officially exhausted . 

Two 、IP Address classification

IP Address is divided into A、B、c、D、E Five category
A Class address range :1.0.0.1~126.255.255.254
A Class address = Network part + The host part of the + The host part of the + The host part of the ( There are class boundaries ) The default subnet mask is /8, namely 255.0.0.0
B Class address range :128.o.0.1～191.255.255.254
B Class address = Network part + Network part + The host part of the + The host part of the ( There are class boundaries ) The default subnet mask is /16, namely 255.255.0.0
C Class address range :192.0.0.1～223.255.255.254
C Class address - Network part + Network part + Network part + The host part of the ( There are class boundaries ) The default subnet mask is /24, namely 255.255.255.0

D Class address range :224.0.0.1～239.255.255.254
Address used for multicast communication
Multicast : A pair of columns
unicast : One to one broadcasting : One to many
E Class address : Range :240.0.0.1～255.255.255.254

Reserved address for scientific research .

  With 127 At the beginning IP All addresses represent local ( Broadcast address 127.255.255.255 With the exception of ),127.0.0.1 Is the local loopback address 169.254.0.0～169.254.255.255DHCP The address assigned when the service fails
Private network address 〈( Hereinafter referred to as private network address ） It refers to the internal network or host IP Address ,IANA( Internet Digital Distribution Agency ） It is stipulated that the following IP Address : Keep as private address , be not in Internet Assigned to , Can be used within a unit or company .RFC1918 The private address specified in the is as follows :

A Class private address :10.0.0.0～10.255.255.25510.0.0.0/8
B Class private address :172.16.0.0 One 172.31.255.255172.16.0.0/12c Class private address :192.168.0.0～192.168.255.255 192.168.0.0/16

  3、 ... and 、 Subnet partition

Network segment composition : network address , You can use IP, Broadcast address

Column :192.168.1.189/24
network number :192.168.1.0
You can use IP:192.168.1.1～192.168.1.254

Broadcast address :192.168.1.255
The subnet mask has 32 Binary bits
Corresponding IP Address : The network part of 1 Express

Corresponding IP The host part of the address is 0 Express

 192.168.1.0/24------>
11000000  10101000  00000001 00000000 IP
11111111    11111111   11111111   00000000 Mask
11000000   10101000  0000000 100000000  network address
192            .168            .1             .0                network address
11000000   10101000  00000001  11111111 Broadcast address
192             168             1                255

 172.16.0.0/12                                                                                    No class
10101100 00010000 00000000 00000000  IP                                 172.16.0.0/12
11111111 11110000 00000000 00000000  Mask                                 255.240.0.0
10101100 0001 0000 00000000 00000000 network address                        172.16.0.0     

 172.16.0.0
10101100 0001 1111 11111111 11111111 Broadcast address                             172.31.255.255

 192.168.100. 100/26
11000000 10101000 01100100 01100100    IP              192.168.100.100
11111111   11111111  11111111   11000000    Subnet mask     255.255.255.192
----------------------------------------------
11000000 10101000 01100100 01000000    network address    192.168.100.64

192.168.100.64
11000000 10101000 01100100 01111111    Broadcast address     192.168.100.127
11111111  11111111   111111111  1111111111
11000000 10101000 01100100  01000000 

IP Address and subnet mask " And " Calculate the network address 0 And any number is equal to 0
1 And any number is equal to any number itself

192.168.1.189/26                                    26------》
11000000.10101000.00000001.10111101     IP Address
11111111.11111111.11111111.11000000          Subnet mask
11000000 .10101000 .00000001.10000000  network address
192.168.1.128
Set all the bits of the host 1 Get the broadcast address 11000000.10101000. 00000001.10111111 Broadcast address
192.168.1.191
Number of subnets =2^n, among n Is the number of bits in the subnet , example :/26,n=26-24
Host number （ You can use IP）=2^N - 2, among N Number of bits for the host part :N=32-26 

26=255.255.255.192  11111111 11111111 11111111 11000000

Number of subnets :2^2=4
Host number :2^6-2=62 Available hosts :62
Available range :0-63、64~127、128~191、192~255 

192.168.100.100/25
Number of subnets :2^1=2
Host number :2^7-2=126    Available hosts 126
Available range :0-127、128~255 

 192.168.100.100/27
Number of subnets :2^3=8
Host number :2^5-2=30    Available hosts 30
Available range :0-31、32~63、64-95、96-127、128-159、160-191、192-223、224-255

192.168.1.0            /24        /25        /26    /27    /28    /29    /30     /31     /32

Subnet mask                 0           128        192   224   240  248    252    254    255
Number of subnets                 1            2            4       8       16     32     64     128    256

IP Number                     256       128         64     32     16      8      4         2        1
You can use IP                    254        126        62      30     14     6      2                   1 

 192.168.1.100/24 Expressed as a fixed IP          255.255.255.0
Simple algorithm
/26=255.255.255.192, On behalf of 26 individual 1, So it is 11111111.11111111.11111111.11000000, Subnet equals 2^6-2=62, So it is 62 Number of hosts , Available range :256-192=64,0~63、64~127、128~191、192~255
according to IP Judging by the type of address n Value :

A Class address : Subnet mask -8
B Class address : Subnet mask - 16

C Class address : Subnet mask - 24

172.16.0.200/20
10101100 00010000 00000000 11001000     

11111111.11111111.11110000 .00000000
10101100 00010000 00000000 00000000  network address 172.16.0.0

172.16.0.200/20
Number of subnets :2^4=16
Host number :2^12-2=4094
Available hosts 4094