Related Terms:
TCP/IP
? TCP / IP (Transmission Control Protocol / Internet Protocol, Transmission Control Protocol / Internet Protocol) refers to the protocol suite enables transmission of information between multiple different networks. TCP / IP protocol refers not only two TCP and IP protocols, but rather refers to a protocol stack consisting of FTP, SMTP, TCP, UDP, IP and other protocols, just as the TCP / IP protocol in the TCP and IP protocol the most representative, it is called TCP / IP protocol.
TCP / IP is the Internet around the world and the most basic core of the agreement, the basis of the Internet.
TCP / IP system:
4. Application Layer: (Telnet, FTP, SMTP) is used to receive data from the transport layer or a different application requirements and methods to transmit data to the transport layer.
3. Transport Layer: (UDP, TCP) and internet user computer information network using the internal data bound channel, data transmission can be achieved and data sharing.
2. Network layer: (ICMP, IP, IGMP) is responsible for packet transmission network.
1. The network access layer (network layer or data link layer interfaces) :( ARP, RARP) primary function is to provide error detection link management of different communication media information for efficient processing details.
Features:
TCP / IP protocol can be developed rapidly and become a de facto standard, it is exactly adapted to the needs of the worldwide data communications. It has the following characteristics:
1. The protocol standard is completely open, it may be available for free use, and independent of the specific computer hardware and the operating system.
2. independent of the network hardware system that can run on a wide area network, more suitable for the Internet.
3. uniformly allocated network address, the network terminal and each device has a unique address.
4. The high-level protocol standardization, can provide multiple reliable network services.
HTTP protocol (Hypertext Transfer Protocol)
? HTTP is a simple request - response protocol, which typically runs on top of TCP. It specifies the client may send a message to the server, and what kind of response obtained.
HTTP is an application layer protocol.
FTP protocol:
? File Transfer Protocol (File Transfer Protocol, FTP) is a standard protocol for file transfer over the network, it works in the seventh layer of the OSI model, Layer 4 TCP model, namely the application layer, using TCP transport instead of UDP, the client and the server before establishing a connection to go through a "three-way handshake" process to ensure that the connection between client and server is reliable and connection-oriented, to provide a reliable guarantee for the data transmission.
? Manner allowing the user to the FTP file operations (such as file add, delete, change, search, transfer, etc.) communicate with each other with another host. However, the user does not actually log on to the computer you want to access the top and become completely user available FTP program to access remote resources, to achieve the user to transfer files back and forth, directory management, and access e-mail, etc., even if the two sides may be equipped with different computer the operating system and file storage.
FTP transmission in two ways: ASCII, Binary.
UDP protocol:
? UDP is the User Datagram Protocol short, the Chinese name is the User Datagram Protocol, is the OSI (Open System Interconnection, Open Systems Interconnection) reference model in a non-transport layer protocol connection, not to provide a simple and reliable transaction-oriented messaging service, IETF RFC 768 is the official specification of the UDP. UDP protocol number in the IP packet is 17.
There does not provide UDP packet grouping, assembly and disadvantages can not sort the data packet, that is, when the message is sent, it is not known whether the complete security arrived.
UDP packets do not guarantee reliability, flow control, and order assurance field and the like, poor reliability. However, because control option less UDP protocol, data transmission delay, high data transmission efficiency, reliability for less demanding applications, or may protect the reliability of the applications, such as DNS, TFTP, SNMP Wait.
OSI protocol
OSI is Open System Interconnection of acronym meaning Open Systems Interconnection. International Organization for Standardization (ISO) developed the OSI model, which defines a standard interconnection of different computers, and the basic frame design described computer network communication. OSI model divides network communications into seven working layers, namely a physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer.
This is a fact to be eliminated TCP / IP 4-layer model agreement. No large-scale use in the world today.
Network layer of the OSI model supports both connection-oriented and connectionless communication, but only supports the transport layer connection-oriented communication; network layer TCP / IP model only provides a connectionless service, but also provides two modes of communication on the transport layer.
IP protocol
IP (Internet Protocol) protocol, also known as Internet Protocol, is the core TCP / IP protocols. It is responsible for communication between network on the Internet, and provides for the transmission of data packets from one network to another network rules to be followed.
Although the IP protocol that makes it possible to send and receive data packets between computers, but it is not responsible for addressing security issues datagram to convey reliability, these safety factors are mainly responsible for the TCP protocol to complete.With this address, it is possible to easily communicate between a computer network users. It is because of IP protocol, the Internet was able to quickly become the world's largest open computer communications network. Therefore, IP protocol also known as the "Internet protocol."
IPv4 address bits is 32, that is, up to 2 ^ 32 computers can be connected to the Internet.
Address bits for IPv6 is 128, which is up to 2 ^ 128 computers can connect to the Internet.
We can specify a single computer with multiple IP addresses, when accessing the Internet, you do not think that an IP address is a computer; in addition, through a specific technology, but also allows multiple servers to share a single IP address, which server the user It looks like a host-like.
IP addresses are divided into two parts network number and host number, the designer must decide how many of each section contains. Network digit number can be assigned directly determines the number of network (a network calculation 2 ^ digit number); host number is the number of bits determines the maximum number of network hosts (Calculation Method 2 ^ -2 host ID bits) .
Today IP networks use 32-bit address in dotted decimal notation, such as 192.168.0.1.
Address format is: IP address = address + host network address or network address = IP address + address + subnet host address.
IP addresses are divided into five categories, A class reserved for government agencies, Class B assigned to medium-sized companies, category C person assigned to any need for multicast class D, E class for experiments, which can accommodate all kinds of The number of different addresses.
Class A addresses
- A Class 1 byte for the network address of the first address, the other three bytes for the host address. It is the first byte of the first bit is fixed to 0.
- Class A network number range address: 0.0.0.0 --- 127.0.0.0 address range 0.0.0.0 to 127.255.255.255.
- Private addresses and reserved addresses Class A address:
① 10.XXX is a private address (the so-called private address is not used on the Internet, and is used in local area network address). Range (10.0.0.0 --- 10.255.255.255)
② and 127.xxx The addresses are reserved and used as cycle testing.
Class B addresses
- Class B addresses 1 byte and 2 bytes for the network address, 2 bytes for the other host address. Its first byte 10 is fixed to the first two.
- Class B network number range address: 128.0.0.0 --- 191.255.0.0. Address range 128.0.0.0 to 191.255.255.255.
- Private addresses and reserved addresses Class B address
① 172.16.0.0 --- 172.31.255.255 is a private address
② 169.254.XX is reserved addresses. If your IP address is automatically obtain an IP address, and you do not find an available DHCP server on the network. You will get one IP.
191.255.255.255 is a broadcast address can not be assigned.
Class C addresses
Class C addresses the first byte, the second byte and the third byte for the network address, the first 4 bytes of the host address. Further the first byte 110 is fixed to the first three.
Class C network number range address: 192.0.0.0 --- 223.255.255.0. Address range 192.0.0.0 to 223.255.255.255
Class C addresses private address:
192.168.XX is a private address. (192.168.0.0 --- 192.168.255.255)
Class D address
- Class D addresses, regardless of the network address and host address, which the first byte is fixed to the first four 1110.
- Class D address range: 224.0.0.0 --- 239.255.255.255
Class E address
- Class E addresses, regardless of the network address and host address, it first pre-fixed at five bytes 11110.
Class E address range: 240.0.0.0 --- 247.255.255.255
If only the IP address ABCDE class division, it will cause a lot of waste: a network of 500 hosts can not use the class C address. But if you use a class B address, more than 60,000 host addresses only 500 are used, resulting in substantial waste of IP addresses. Therefore, IP addresses, also supports VLSM technology, on the basis of class ABC network, based on further subnetting.