So, what is a "data packet"? What are its characteristics? Data packet is also a form of packet switching, that is, the transmitted data is divided into "packets" before transmission. However, unlike the traditional "connected" packet switching, it belongs to the "connectionless" type and sends each typed "packet" as an "independent message", so it is called "data packet". In this way, there is no need to connect the circuit before starting communication, and all data packets 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.
Every packet has two parts: a header and a message. The header contains necessary contents, such as the destination address, so that each packet 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 the packet can also be changed according to the packet size specified by the delivery network, and the maximum length of the IP packet can reach 65,535 bytes.
Another important content in the IP protocol is to provide every computer and other equipment on the Internet with a unique address 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. Nowadays, telecommunication network is merging with IP network, and new technologies based on IP are popular technologies, such as VoIP, and other technologies, such as IP over ATM, IPover SDH, IP over WDM, etc. , is the research hotspot of IP technology. IPV4 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.
When an IP address is divided into two parts: the network number and the host number, the designer must decide how many bits each part contains. The number of digits of the network number directly determines the number of networks that can be allocated (calculation method 2: Number of digits of the network number); The number of digits of the host number determines the maximum number of hosts in the network (calculation method 2 host number digits -2). However, because the network scale contained in the whole Internet may be relatively large or relatively small, the designer finally chose a flexible scheme: dividing the IP address space into different categories, and each category has a different network number and host number.
IP address is the basis of data transmission in IP network. It identifies a connection in an IP network, and a host can have multiple IP addresses. The IP address in the IP packet remains unchanged in the network transmission.
(1) Basic Address Format (IPv4)
The current IP network uses 32-bit addresses, which are expressed in dotted decimal system, such as 192 438+068.0. 1.
Address format: IP address = network address+host address or IP address = network address+subnet address+host address.
Network addresses are assigned by ICANN (Internet Corporation for Assigned Names and Numbers) of the Internet Society. InterNIC is responsible for North America, RIPENIC is responsible for Europe, and APNIC is responsible for Asia-Pacific, in order to ensure the global uniqueness of network addresses. The host address is assigned by the system administrator of each network. Therefore, the uniqueness of network address and the uniqueness of host address in the network ensure the global uniqueness of IP address.
(2) Allocation of reserved addresses
According to different purposes and security levels, IP addresses can also be roughly divided into two categories: public addresses and private addresses. Public addresses are used on the Internet and can be accessed at will. Private addresses can only be used in internal networks, and only through proxy servers can they communicate with the Internet.
ip address inquiries
Start-Run, enter cmd-enter ipconfig/all in the pop-up dialog box, and then press enter to appear in the list.
One of them: an ip address is an ip address.
Classification of IP addresses
Network number: used to identify the network where the host is located;
Host number: used to identify the host in this network.
IP addresses are divided into five categories: A reserved for government agencies, B allocated to medium-sized companies, C allocated to anyone who needs it, D used for multicast, and E used for experiments. The number of addresses that can be accommodated in each category is different.
Characteristics of class A, B and C IP addresses: When IP addresses are written in binary form, the first digit of class A address is always 0, the first two digits of class B address are always 10, and the first three digits of class C address are always 1 10.
1. Class address
(1) The1byte of Class A address is the network address, and the other three bytes are the host address.
(2) Class A address range:1.0.1-126.255.254.
(3) Private address and reserved address in Class A address:
(1)10.x.x.x is a private address (the so-called private address is an address that is not used on the Internet but used in the local area network).
Range (10.0.0-10.255.255)
② 127.X.X.X is a reserved address for loop testing.
2. Class B address
The 1 byte and the second byte of (1) Class B address are the network address, and the other two bytes are the host address.
(2) Class B address range:128.0.1-191.255.254.
(3) Private address and reserved address of Class B address
①172.16.0.0-172.31.255.255 is a private address.
② 169.254.X.X is a reserved address. If your IP address is automatically obtained and you can't find an available DHCP server on the network. You will get an IP.
3. Class C address
(1)1byte of class C address, the second byte and the third byte are the network address, and the fourth byte is the host address. In addition, the first three bits of the byte 1 are fixed as 1 10.
(2) Class C address range:192.0.0.1-223.255.255.254.
(3) Private address in Class C address:
192. 168.X.X is a private address. ( 192. 168.0.0- 192. 168.255.255)
4. Class D address
(1) Class D addresses do not distinguish between network addresses and host addresses, and the first four bits of the1byte are fixed as110.
(2) Class D address range: 224.0.01-239.255.255.254.
5. Class E address
(1) Class E addresses do not distinguish between network addresses and host addresses, and the first five digits of the1byte are fixed as111.
(2) Class E address range: 240.0.01-255.255.254.
The concept of IP is very broad, including brand, trademark, copyright, and most importantly, business secrets, business models, business standards and so on. The amount of intellectual property ownership is the most important symbol to distinguish manufacturing from creation. If a country has too little IP, its industry or enterprise can only play the role of primary processor in the international division of labor.
Special IP address
In the IP address space, some IP addresses cannot be assigned to devices, some IP addresses cannot be used in public networks, and some IP addresses can only be used in this machine. There are many such special IP addresses:
Restricted broadcast address
Broadcast communication is a one-to-many communication mode. If the binary digits of an IP address are all 1, that is, 255.255.255.255, then this address is used to define the whole Internet. If the device wants IP datagrams to be received by the whole Internet, it will send a broadcast packet with the destination address of 1, but this will bring a disastrous burden to the whole Internet. Therefore, all routers on the network will prevent this type of packet from being forwarded, thus limiting this kind of broadcast to the local network segment.
Directional broadcast address
The last address in the network is a direct broadcast address, which means that all HostID are 1. The host uses this address to send IP datagrams to all devices in the local network segment, and the router will forward the datagrams to all hosts in a specific network.
Note: This address can only be used as the destination address in IP datagrams. In addition, direct broadcast addresses reduce the number of addresses that can be assigned to devices in a network segment by 1.
The IP address is 0.0.0.0.
If all IP addresses are 0, that is, 0.0.0.0, then this IP address can only be used as the source IP address in the IP datagram. This happens when the device starts but does not know its own IP address. This kind of address is very common in the network environment where DHCP is used to assign IP addresses. In order to obtain an available IP address, the user host sends an IP packet to the DHCP server, and takes this address as the source address and the destination address is 255.255.255.255 (because the host does not know the IP address of the DHCP server at this time).
IP address with NetID 0.
This address can be used when a host sends a message to other hosts in the same network segment, and the router will not forward the packet. For example,12.12.12.0/24, one host in this network,12.2/24, another host in the same network,124.
Loopback address
All addresses in the 127 network segment are called loopback addresses, which are mainly used to test whether the network protocol works normally. For example, ping127.1.1can be used to test whether the local TCP/IP protocol is installed correctly. Another use is that when a client process sends a message with a loopback address to a server process located on the same machine, for example, by typing 127. 1.2.3 in the browser, it can be used to test whether IIS starts normally when network routing is excluded.
Private address
In IP address space, some IP addresses are defined as private addresses. This kind of address can't be assigned to internet network equipment, and can only be used within the enterprise, so it is also called private address. If you want to use such an address on the Internet, you must use network address translation or port mapping technology.
These proprietary addresses are:
10/8 Address range: 10.0.0 to 10.255.255 * * The address is 2 to the 24th power.
172. 16/ 12 address range: 172. 16.0.0 to172.31.255.255 *.
192.168/16 Address range: 192. 168.0.0 to192.168.255.255. Development and characteristics of IPV6 IPv6 is the abbreviation of "Internet Protocol Version 6", also known as the next generation Internet protocol. It is a new IP protocol designed by IETF (Internet Engineering Task Force) to replace the current IPv4 (current IP) protocol.
As we know, all Internet hosts have a unique IP address, and the IP address represents a host number with a 32-bit binary number. However, 32-bit address resources are limited, which can no longer meet the needs of users. Therefore, Internet research institutions have released a new host identification method, namely IPv6. In RFC 1884 (RFC is the abbreviation of document for soliciting opinions. RFC is actually some Internet standards about services), and the stipulated standard syntax suggests that the 128 bits (16 bytes) of IPv6 address be written as an unsigned integer with 8 bits 16, each integer is represented by 4 hexadecimal bits, and these numbers are separated by a colon (:), for example: 3ffe: 320/.
IPv6 features:
Extended addressing capability
IPv6 extends the length of IP address from 32 bits to 128 bits, supporting more levels of address hierarchy, more addressable nodes and simpler address automatic configuration. By adding a "range" domain to the multicast address, the scalability of multicast routing is improved. A new address type called "anycast address" is also defined to send packets to any node in the group.
Simplified title format
Some IPv4 header fields have been deleted or become optional fields to reduce the consumption of routine processing in packet processing and limit the bandwidth consumed by IPv6 headers.
Improvements to Extended Title and Option Support
The change of IP header option coding method can improve forwarding efficiency, make the restriction of option length more relaxed, and provide greater flexibility for introducing new options in the future;
Ability to identify streams
A new capability is added, which makes it possible to identify packets belonging to a specific communication "stream" that the sender needs special treatment (such as "real-time" service for non-default quality of service);
Authentication and encryption functions
IPv6 specifies extended functions to support authentication, data integrity and (optionally) data confidentiality. Other meaning with IP 1. In electronic products, IP means waterproof and dustproof level.
The International Electrotechnical Commission (iec) drafted the IP (International Protection) protection rating system. Lamps and lanterns are classified according to their dustproof, foreign body intrusion-proof, waterproof and moisture-proof characteristics. The foreign objects mentioned here, including tools and people's fingers, must not touch the live parts in the lamps to avoid electric shock.
The IP protection level consists of two numbers. The first number indicates the dustproof and foreign body intrusion prevention level of the lamp. The second number indicates the tightness of the lamp against moisture and water intrusion. The higher the number, the higher the protection level. Table 1 and Table 2 show the protection levels indicated by two tag numbers.
The protection level indicated by the first characteristic number (number)
The first marked number:
0 No protection, no special protection for people or things other than IP0-
1 Prevent the intrusion of solid objects larger than 50mm, and prevent the human body (such as palm) from accidentally contacting the parts inside the lamp. Prevent foreign bodies with larger size (diameter greater than 50mm) from invading IP 1-
2 to prevent the invasion of solids larger than 12mm, and to prevent people's fingers from touching the internal parts of lamps. Prevent medium-sized foreign objects (diameter greater than12mm and length greater than 80mm) from invading IP2-
3 to prevent the invasion of solids larger than 2.5mm, and to prevent tools, wires or similar small foreign bodies with a diameter or thickness larger than 2.5mm from invading and contacting the internal parts of lamps and lanterns IP3-
4. Prevent the invasion of solid objects larger than 1.0mm, and prevent tools, wires or similar small foreign objects with a diameter or thickness larger than 1.0mm from invading and contacting the internal parts of lamps and lanterns IP4-
5 dust-proof, completely prevent foreign bodies from invading. Although dust intrusion cannot be completely prevented, the amount of dust intrusion will not affect the normal work of lamps.
6 Dust density can completely prevent foreign bodies from invading IP6-
Protection level indicated by the second characteristic number (number)
The second number:
0 is unprotected, and there is no special protection for people or things other than IP-0.
1 Prevent dripping water from invading, and vertical dripping water (such as condensed water) will not have harmful effects on lamps and lanterns IP- 1.
When the lamp is tilted to15, it can still prevent the intrusion of dripping water. When the lamp is tilted from the vertical to15, dripping water will not have harmful effects on the lamp. IP-2
3. Prevent the sprayed water from invading, and prevent the sprayed water from entering the lamps and lanterns at an angle less than 60 from the vertical direction, thus causing damage to IP-3.
4 Prevent splashing water from invading, and prevent splashing water from all directions from entering the lamps and causing IP-4 damage.
5. Prevent the injected water from invading, and prevent the water sprayed by the nozzle from all directions from entering the lamps and causing damage to IP-5.
6. Prevent the invasion of big waves, and install lights on the deck to prevent IP-6 from being damaged by flooding due to the invasion of big waves.
7. Prevent water intrusion when immersed in water. If the lamp is immersed in water for a certain period of time or the water pressure is lower than a certain standard, it can be ensured that IP-7 will not be damaged by water ingress.
8. Prevent water from entering when sinking. If the lamp sinks indefinitely and the water pressure is specified, it can be ensured that IP-8 will not be damaged by water ingress.
2.IP stands for entrance protection
The first identification number of the grade, such as IP6_, indicates the dust-proof grade (6 indicates that no dust enters, see the table below).
The second number, such as IP_5, indicates the waterproof protection level (5 indicates the spraying of protective water, see the table below).
Prevent the invasion of solid substances.
The first number defines the description of preventing liquid intrusion–the second number defines the description.
0 is not protected. No special protection. 0 is not protected. No special protection.
1 Protect solid foreign bodies with a diameter of 50mm or more. Protect objects with large surface area, such as hands (against intentional intrusion). 1 Protective water droplets (water droplets falling vertically)
2 Prevent solid foreign bodies with a diameter of12mm or more. Protect fingers or other objects with a length not exceeding 80 mm 2 When the equipment is tilted 15 degrees, it will prevent water droplets. Water drops falling vertically should not cause harm.
3 Protect solid foreign bodies with a diameter of 2.5 mm or more. Protective tools, metal wires, etc. Its diameter or thickness exceeds 2.5 mm .. 3 to protect the spilled water. Water splashing from both sides of the vertical line at an angle of 60 degrees should not cause damage.
4 Protect solid foreign bodies with a diameter of 1.0mm or more. Protect metal wire or metal strip with thickness greater than1.0 mm. 4 Protective water spraying. When the equipment tilts to the normal position of 15 degrees, water spraying aimed at the equipment from any direction should not cause damage.
5 dustproof. It is impossible to completely prevent dust from entering, but the amount of dust will not affect the normal operation of the equipment. 5. Protect the sprinkler. Spraying water on the equipment from any direction will not cause damage.
6 dustproof. No dust has entered. 6 prevent big waves. The amount of water that big waves or strong currents enter the equipment should not cause damage.
7 flood protection. When immersed in water under the specified pressure and time, there should be no water that will cause damage.
8 prevent flooding. Under the conditions specified by the manufacturer, the equipment can be immersed in water for a long time.
The test method and main test conditions of water resistance test (ip5) are defined as follows:
Test method-The nozzle has an inner diameter of 6.3 mm and is placed 2.5-3 meters away from the test sample.
Water flow–12.5L/min 5%
Test duration–1min/m2, but at least 3 minutes.
Test conditions–Spray test samples from every feasible angle.
3. In 8088 or 8086, IP (instruction pointer) refers to the instruction pointer register, which is a register inside the CPU to store the offset of the next instruction to be executed. Its value can be changed by JMP instruction, for example, using JMP AX to change IP with AX value, thus realizing inter-segment jump.
4. Intellectual property rights
IP is the abbreviation of intellectual property, which means intellectual property.
Intellectual property is an intangible property right, also known as intellectual achievement right, which refers to the achievements obtained through intellectual creative labor and is the exclusive right enjoyed by intellectual workers according to law. Such rights include personal rights and property rights, also known as moral rights and economic rights. The so-called personal right means that the right is inseparable from the person who has made intellectual achievements, and it is a legal reflection of personal relationship. For example, the author's right to sign the work, or the right to publish and modify the work, and so on. The so-called property right refers to the right that the obligee can use the intellectual labor achievement to get remuneration or reward after it is recognized by law. This right is also called economic right. The object of intellectual property protection is the creation of human mind and intelligence, the right of human intellectual achievements, and the right enjoyed by intellectual achievements created by all intellectual activities in science, technology, culture and art according to law. Intellectual property is a legal concept widely used in the world.
Intellectual property rights include industrial property rights and copyrights (called copyrights in China). Industrial property rights include patents, trademarks, service marks, names of manufacturers, names of countries of origin and prevention of unfair competition. Copyright refers to the right of a unit or individual to print, publish and sell a work according to law. Anyone who wants to copy, translate, adapt or perform needs permission from the copyright owner, otherwise it will infringe on the rights of others. The essence of intellectual property rights is to treat human intellectual achievements as property.
Trademark right refers to the exclusive right given by national laws to trademark owners to protect their registered trademarks. A trademark is a commercial symbol used to distinguish goods and services from different sources. It consists of words, graphics, letters, numbers, three-dimensional symbols, color combinations or combinations of the above elements. The acquisition of trademark rights in China must fulfill the trademark registration procedure and implement the principle of first application.
Copyright is the creator and creator of literary, artistic and scientific works, and it is a civil right enjoyed by their works according to law.
Patent right and patent protection refer to the patent application filed with the State Patent Office, and after passing the examination according to law, the patent applicant is granted the exclusive right to enjoy the invention and creation within a specified time. After an invention-creation is granted a patent right, the patentee enjoys exclusive rights to his invention-creation. No unit or individual may exploit its patent without the permission of the patentee, that is, it may not manufacture, use, promise to sell, sell or import its patented products for production and business purposes. Without the permission of the patentee, the implementation of his patent will infringe his patent right and cause disputes, which shall be settled by the parties through consultation; Unwilling to negotiate or if negotiation fails, the patentee or interested party may bring a lawsuit to the people's court or request the administrative department for patent affairs to handle it. Patent protection adopts the protection mode of "two-way parallel and judicial guarantee" between judicial and administrative law enforcement. The administrative protection in this area takes the form of patrol law enforcement and joint law enforcement, focusing on cracking down on group infringement, repeated infringement and other phenomena that seriously disturb the patent legal environment.
Three characteristics of intellectual property rights
1, exclusivity of intellectual property, that is, exclusivity or monopoly;
2. The regionality of intellectual property, that is, it is only valid in the confirmed and protected areas;
3, the timeliness of intellectual property rights, that is, only within the prescribed protection period.
Internet Protocol (internet protocol)
Abbreviations.
1. Internet Protocol Computer Internet Communication Protocol
5. The rank of Hong Kong Police.
Ip is the abbreviation of Inspector of Police: monitor.
6. Short for Interpol
Ip is also the abbreviation of Interpol "I" NTER National Criminal Police Organization.