TCP/IP protocol details

OSI communication protocol model (Open System Interconnection)

 

The OSI (Open System Interconnection) communication protocol model is a multi-layer communication protocol proposed by ISO. An open system is a set of protocols that allow any two systems with different basic architecture to communicate. Theoretically, OSI allows communication between any two computers. The OSI model divides the network into a layer-7 model:

Each layer in the OSI model only communicates with the upper and lower layers adjacent to each other. High-level protocols focus on processing user services and various application requests, while underlying protocols focus on actual information transmission. The purpose of layering is to separate various specific functions, and each layer is relatively independent.

 

TCP/IP protocol model

OSI communication protocol is only a theoretical model, and the most used is TCP/IP protocol. The TCP/IP protocol model divides the network into a layer-4 model:

• Application)

The application layer corresponds to the application layer of the OSI model. It provides applications with the ability to access services at other layers and defines the protocol that applications use to exchange data.

• Transport)

The transport layer corresponds to the transport layer and some Session Layer functions of the OSI model. It provides session and datagram communication services for the application layer. The core protocol of the transport layer is the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP ).

• Network)

The network layer is also called the Internet layer. It is applied to the network layer of the OSI model and is responsible for addressing, packaging, and packet forwarding mechanisms from one or more routers to the final target.

• Network Access)

The network access layer corresponds to the physical layer and data link layer of the OSI model, and is responsible for placing TCP/IP packets on the network transmission medium and receiving TCP/IP packets from the network transmission medium.

 

TCP/IP protocol family

The so-called TCP/IP protocol family does not simply refer to the TCP and IP protocols, but includes a network protocol set of many other protocols, called the protocol family:

• IP

The internetprotocol is used to route data between hosts and store data on the network. It also provides Group Sending services for ICMP, TCP, and UDP. User processes do not involve this layer.

• ARP

Address Resolution Protocol, which maps Network (IP) addresses to hardware (MAC) addresses.

• RARP

Reverse Address Resolution Protocol, which maps hardware (MAC) addresses to network (IP) addresses.

• ICMP

Internet Control Message Protocol, which processes information and host errors and transmission control.

• TCP

Transmission Control Protocol is a reliable connection-oriented full-duplex byte stream protocol provided to user processes. It provides virtual circuit services for user processes and establishes a check for reliable data transmission. Most network user programs use TCP.

• UDP

User Datagram Protocol, which is a connectionless protocol provided to user processes. It is used to transmit data without performing a correctness check.

• FTP

File Transfer Protocol (file transfer protocol) allows you to communicate with another host in the form of File Operations (File addition, deletion, modification, query, transfer, etc.

• SMTP

Simple Mail Transfer Protocol, which is used to send emails between systems.

• TTP

The terminal protocol (Telnet terminal Protocol), which allows users to access the remote host through a virtual terminal.

• HTTP

Hypertext Transfer protocol is used to transmit files written in HTML or Hyper Text Markup Language, that is, webpages.

• TFTP

Trivial File Transfer Protocol is used to transmit "simple" files. Unlike FTP, it uses UDP port 69, therefore, it can traverse many firewalls.