What is IP?

Internet Protocol

Brief introduction of intellectual property rights

Every host on the Internet has a unique IP address. IP protocol uses this address to transfer information between hosts, which is the basis of Internet operation. The IP address is 32 bits long, divided into 4 segments, each segment is 8 bits, expressed by decimal digits, and the range of each segment is 1 ~ 254, and segments are separated by periods. For example,159.226.1.1. An IP address consists of two parts, one is the network address, and the other is the host address. IP addresses are classified into classes a, b, c, d and E5. Commonly used are B and C, and the Ip address is just like our home address. If you want to write a letter to a person, you should know his or her address so that the postman can deliver the letter. A computer sends information just like a postman. It must know the unique "home address" so as not to send the letter to the wrong person. It's just that our address is expressed in words, and the address of the computer is expressed in decimal numbers.

As we all know, in telephone communication, telephone users are identified by telephone numbers. Similarly, in order to distinguish different computers in the network, it is also necessary to assign a number to the computer, which is an "IP address".

What is an IP address?

The so-called IP address is a 32-bit address assigned to each host connected to the Internet.

According to TCP/IP (Transmission Control Protocol/Internet Protocol) protocol, IP addresses are expressed in binary, and each IP address is 32 bits long, which is 4 bytes when converted into bytes. For example, a binary IP address is "000010100000000000001",which is too long for people to handle. In order to facilitate people's use, IP addresses are often written in decimal form, with the symbol "."separating different bytes in the middle. Therefore, the above IP address can be expressed as "10.0.0. 1". This representation of IP address is called dotted decimal representation, which is obviously much better to remember than 1 and 0.

Some people think that a computer can only have one IP address, which is wrong. We can specify that a computer has multiple IP addresses, so when accessing the Internet, don't think that an IP address is a computer. In addition, through specific technology, multiple servers can use one IP address, and these servers look like a host to users.

How to assign IP addresses

TCP/IP protocol needs different settings for different networks, and each node generally needs an IP address, a subnet mask and a default gateway. However, Dynamic Host Configuration Protocol (DHCP) can automatically assign an IP address to the client, which can avoid errors and simplify the setting of TCP/IP protocol.

So, how to assign IP addresses in the LAN? IP addresses on the Internet are managed by an organization called "IANA" (Internet Assigned Numbers Authority).

What is IP?

-IP is a popular technology at present. A number of new terms related to this, such as IP network, IP exchange, IP telephone, IP fax and so on, have also appeared one after another. So, what is IP?

-IP is the abbreviation of English Internet Protocol, which means "protocol for interconnection between networks", that is, a protocol designed for communication between computer networks. In the internet, it is a set of rules that can make all computer networks connected with the internet communicate with each other, and stipulates the rules that computers should abide by when communicating on the internet. As long as it conforms to the IP protocol, any computer system produced by any manufacturer can be interconnected with the Internet. It is precisely because of the IP protocol that the Internet has rapidly developed into the largest and most open computer communication network in the world. Therefore, IP protocol can also be called "Internet protocol".

-How does IP realize network interconnection? Network systems and devices produced by different manufacturers (such as Ethernet and packet-switched networks) cannot communicate with each other. The main reason why they can't communicate with each other is that the formats of the basic units (technically called "frames") of the data they transmit are different. IP protocol is actually a set of protocol software composed of software programs, which converts various "frames" into "IP datagram" format. This transformation is one of the most important features of the Internet, which enables all kinds of computers to communicate with each other on the Internet, that is, it has the characteristics of "openness".

-So, what is a datagram? What are its characteristics? Datagram is also a form of packet switching, that is, the transmitted data is segmented into "packets" before transmission. But unlike the traditional "connected" packet switching, it belongs to the "connectionless" type, and each typed "packet" is sent as an independent message, so it is called "datagram". In this way, there is no need to connect the circuit before starting communication, and all datagrams may not be transmitted through the same path, so it is called "connectionless". This feature is very important, which greatly improves the robustness and security of the network.

-Each datagram has two parts, a header and a message. The header contains necessary contents, such as the destination address, so that each datagram can reach the destination accurately without going through the same path. Recombined and restored to the original data at the destination. This requires IP to have the function of package encapsulation and assembly.

-In the actual transmission process, the length of datagram can be changed according to the packet size specified through the network, and the maximum length of IP datagram can reach 65535 bytes.

Another important content in the IP protocol is to give every computer and other equipment on the Internet a unique address, which is called "IP address". Because of this unique address, when users operate on networked computers, they can effectively and conveniently select the objects they want from thousands of computers in Qian Qian.

-At present, telecommunication networks are merging with IP networks, and new technologies based on IP are hot technologies, such as VoIP. Others, such as IP over ATM, IPover SDH and IP over WDM, are hot topics in IP technology research.

IP address type

When the Internet was originally designed, in order to facilitate addressing and hierarchical networking, each IP address contained two identification codes (IDs), namely the network ID and the host ID. All hosts on the same physical network use the same network ID, and a host on the network (including workstations, servers and routers on the network) has a corresponding host ID. According to the different network ID, IP addresses can be divided into five types: Class A address, Class B address, Class C address, Class D address and Class E address.

IP address classification

1 class. Ip address

Class A IP address consists of 1 byte network address and 3 bytes host address. The highest digit of the network address must be "0", and the address range is from 1.0.0.0 to 126.0.0. There are 126 Class A networks, and each network can accommodate more than 1 100 million hosts.

2. Class B IP address

Class B IP address consists of two bytes of network address and two bytes of host address. The highest digit of the network address must be "10", and the address range is128.0.0 to 19 1.255.255. There are 16382 Class B networks, each of which can accommodate more than 60,000 hosts.

3. Class C IP address

Class C IP address consists of a 3-byte network address and a 1 byte host address. The most significant bit of the network address must be "1 10". The range is from 192.0.0 to 223.255.255.255. There are more than 2.09 million Class C networks, and each network can accommodate 254 hosts.

4. Class D addresses are used for multicast.

The first byte of a Class D IP address begins with "lll0", which is a specially reserved address. It does not point to a specific network. At present, this address is used for multicast. Multicast address is used to address a group of computers at a time, which identifies a group of computers sharing the same protocol.

5. Class E IP address

Start with "llll0" and reserve it for future use.

All zeros ("0.0.0.0") address corresponds to the current host. The IP address of all "1"("255.255.255.255") is the broadcast address of the current subnet.

Who assigned the IP address?

All IP addresses are assigned by NIC (Network Information Center), an international organization. At present, there are three such network information centers in the world.

Inter: responsible for the United States and other regions;

ENIC: responsible for Europe;

APNIC: responsible for the Asia-Pacific region.

China applied for an IP address through APNIC, which is headquartered in Tokyo University. When applying, you should consider what kind of IP address to apply for and then submit it to the domestic agency.

What are public and private addresses?

Internic (Internet Network Information Center) is responsible for the public address. These IP addresses are assigned to organizations that register and apply for Inter NIC. Access the internet directly through it.

Private addresses are unregistered addresses and are used exclusively for internal organizations.

The reserved internal private addresses are listed below.

Class a10.0.0-10.255.255.255

Class b:172.16.0.0-172.438+0.3336.

Class C:192.168.0.0-192.654438+068. 5668686

Reserved IP address

When the Internet was originally designed, in order to facilitate addressing and hierarchical networking, each IP address contained two identification codes (IDs), namely the network ID and the host ID. All hosts on the same physical network use the same network ID, and a host on the network (including workstations, servers and routers on the network) has a corresponding host ID. According to the different network ID, IP addresses can be divided into five types: Class A address, Class B address, Class C address, Class D address and Class E address.

There is a cmd command to find tracert and add Ip address, so you can view the route you have passed!