What are the common network protocols

1、 Basic concepts of protocol and protocol stack

1.1、 What is an agreement

A protocol is a set of rules for communication between computers or devices in a network . Common protocols are IP、TCP、HTTP、POP3、SMTP etc. .

1.2、 What is a protocol stack

In the network , In order to complete the communication , Multiple protocols on multiple layers must be used . These protocols are grouped together in hierarchical order , Constitute the protocol stack (Protocol Stack), Also known as protocol family (Protocol Suite).

1.3、 The role of the agreement

There are two main functions of a network protocol ： One is to establish virtual communication between peer layers , The second is to realize the independence between levels .

1.4、 The independence between levels

The so-called inter level independence , It refers to the communication between the higher level and the adjacent lower level , Just use the interfaces and services provided by the lower level , You don't need to know the details of the algorithm and protocol used by the low-level implementation of this function ; The lower level only uses the parameters and control information transmitted from the high-level system , That's the level of indifference .

2、 Network protocol family / Stack composition

The role of network communication protocol is to establish communication channels on the network and control the rules of information flow through the channels . For network communication , Both sides of the communication must abide by the communication agreement

explain ： Network protocols and standards are based on OSI Seven layer model , Each layer has its own protocol .

3、 Common network protocols

TCP/IP： Industrial standards 、 Open protocol ,Internet The standard of the Internet

IPX/SPX：Novell Developed Netware The protocol used by the operating system ,IPX Internet packet switching protocol , Working at the network layer ,SPX For sequential packet exchange protocol , Working on the transport layer .

NetBIOS/NetBEUI： Smaller protocol stack , be applied to IBM And the early ones Windows System , Now? Windows Still supported .

AppleTalk：Apple The company's Mac OS The network protocol used in .

（1）TCP/IP agreement

TCP/IP It's a layered protocol , As shown in the hierarchy ： From the bottom to the application layer , The physical layer , The link layer , The network layer , Transport layer , application layer . Data is encapsulated layer by layer , The way of encapsulation is to add a data control header in front of the original data .

author ： Zhibotong Electronics link ：https://www.zhihu.com/question/401244046/answer/1291721422 source ： You know The copyright belongs to the author . Commercial reprint please contact the author for authorization , Non-commercial reprint please indicate the source .

（2）Telnet agreement

Telnet yes TCP/IP An application protocol in , It can provide support for terminal simulation . Enables the user to connect to the host , Make the host respond as if it were directly connected to the terminal .Telnet Use... At the sender and receiver TCP Of 23 Port number for dedicated communication .

（3）FTP agreement

FTP Agreement to use TCP20 Number and 21 Port no. ,20 Port number is used for data exchange ,21 Port number is used to establish a connection , Allow directory and file access , Upload and download , Cannot execute file remotely .

TFTP It's simple file transfer protocol （Trivial File Transfer Protocol,TFTP）,TFTP It's disconnected , Use UDP Of 69 Port no. , It is used to transfer small files when data transfer errors are insignificant and security is not required .

（4）SMTP agreement

SMTP It's simple mail transfer protocol （Simple Mail Transfer Protocol,SMTP） It's designed for e-mail exchange between network systems . Use 25 port .SMTP Just need an email address on the receiving end to send the email .POP3 The protocol is used to receive mail . Use 110 port

（5）DNS service

DNS It's domain name resolution service （Domain Name Service, DNS）, The function is to convert the domain name to IP Address , Or will IP Address to domain , Used to resolve fully qualified domain names （FQDN）. Use 53 Port no. .

（6）DHCP service

DHCP Is the dynamic host configuration protocol (DHCP), What information can the server provide :

1、IP Address

2、 Subnet mask (subnet mask)

3、 domain name (domain name)

4、 The default gateway (default gateway)

5、DNS