Some network protocol protocols

A network protocol is a collection of standards, rules, and norms that a computer uses to Exchange data over a network. Common protocols are TCP protocol, IP Protocol, UDP protocol, ICMP protocol. These are all transport protocols, as well as application layer protocols such as HTTP protocol, FTP protocol, etc. This application layer protocol is meant to tell other computers what they mean by sending their own data.

IP protocol: This protocol is the network layer protocol, IP is similar to each host's house number, through the IP to determine which host to send the data. IP currently has two versions IPv4 and IPV6, in fact IPv4 is a 32-bit binary number, but also is divided into ABCDE five classes of IP address, IP address = Network address + host address or IP address = Network address + subnet address + host address. The IP protocol is only responsible for sending and receiving data, and does not care about the accuracy of the data. No retransmission and confirmation.

TCP protocol: This Protocol belongs to the Transport layer protocol, which is used for data transmission. is a reliable transmission protocol, each time the data received to reply to a confirmation message. First, connect with the host that needs to be connected-three handshake: first send the connection signal, the client waits for the service side to respond, The server receives a connection request sends a confirmation message, and allocates system resources for the connection, enters the wait state, and after the client receives the reply, sends a confirmation message to the server three times the handshake is complete. The data to be sent is sliced and numbered, and each time the data is received, a corresponding number confirmation is returned. And after a certain period of time, the sender will retransmit the data, and if the receiver has already received the packet, the packet will be discarded. Returns the acknowledgement signal, as well as the time-out retransmission mechanism when the data is received. So that the data transmission is basically not the risk of packet loss. End transfer requires four waves: The TCP client sends a fin to turn off the client-to-server data transfer, the server receives the fin, it sends back an ACK, and confirms that the sequence number is the received sequence number plus 1. As with Syn, a fin will occupy a sequence number. The server shuts down the client connection and sends a fin to the client. The client sends back ACK message acknowledgement and sets the confirmation sequence to receive the serial number plus 1

UDP protocol: The Protocol is also a transport layer protocol, but also for the transmission of data, is an unreliable transport protocol, the Protocol does not need to pre-connect, and does not retransmit, received data do not return confirmation information, so that the transmission of data has the risk of packet loss, but because there is no early connection, so the consumption of less resources, The protocol can be used when the correctness requirement is low. The protocol is also used for broadcasting, multicast, etc.

ICMP protocol: The Protocol is a network layer protocol that does not transmit data and is used to view the network properties of the local host to the target host, such as whether the network is available, the routing information, and whether the target host can reach the information. There is no specific port, because the data is not transferred, so the port is not required.

The application layer protocol is to send some strings, and then the receiver parses the string to understand what the sender needs the receiver to do. Does not involve the transmission of data. Detailed later.

Some network protocol protocols