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IP addressing

The IP address is the only identification number assigned to the IP network, indicating the specific location of the host in the network.

The main purpose of IP is to enable hosts in one network to communicate with hosts in another network, regardless of the type of host.

The IP address is 32 bits long and is divided into 4 bytes (8 bits each).

You can express it in three ways

1) dotted decimal system

2) binary

3) hexadecimal

General binary and hexadecimal are easy to identify and easy to use. But hexadecimal is also used.

The reason why the 1P address is a structured address and does not choose a flat addressing scheme is.

1) the advantage of structured addresses is that the total address is 2 ^ 32 = 4 294 967 296.

2) the determination of the plane addressing scheme is related to the routing.

IP is a structured address, all of which are partly network addresses and partly host addresses.

Network address

The network address uniquely identifies the network, and the network address of each network is equal. For example, 172.16.12.1, the network address is 172.16.

Host address

Every machine in the network has a node address (host address). An IP address leaves the network and the rest is the node address. Each node address must be unique, because the host of a network is unique. For example, 172.16.12.1, the network address is 172.16 and the host address is 12.1.

According to the network model, the Internet designs five kinds of network models, which are Class A, Class B, Class C, Class D and Class E.

8 bit 8 bit

Class A network bit host bit

Type B network bit network bit host bit host bit

Class C network bit host bit

Class D for Multicast

Class E is used in scientific research

Reserved IP addr

The network bits are all 0. Current network segment

The network bits are all 1 and all network segments

The host bits are all 0. Any host in this network segment

The host bits are all 1. All hosts in this network segment

Both network bits and host bits are 0 default routes, which can replace any network.

Both the network bit and the host bit are 1 broadcast addresses, representing all hosts in the network

127.0.0.1 for loopback testing

Class An address range

Format network.node.node.node

The first bit of the network address must be 0

Therefore, the network address range is 00000000-01111111.

So the network address is 0-127 (but 0 and 127 are not legal network addresses)

The host address has 3 digits, but it cannot all be set to 0 or 1. So each network segment can have 2 ^ 24-2 hosts.

Class B address range

Format netwodrk.network.node.node

The first two places in the network must be 10

Therefore, the network address range is 10000000-10111111.

So the value of network address is 128-191.

There are 2 ^ 16-2 hosts that can exist in each network.

Class C address range

Format network.network.network.node

The first network bit must be 110

Network values range from 192 to 223

Class D, Class E

224-239 for Multicast

240-255 for scientific research

Private IP address

It can be used in private networks, but it is not routable in the Internet.

Objective: to solve the depleted IP address resources and help save valuable IP resources.

Reserved IP private addresses are

Address space reserved by address type

Class A 10.0.0.0-10.255.255.255

Class B 172.16.0.0-172.31.255.255

Class C 192.168.0.0-192.168.255.255

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