What Is the Definition of Packet Switching Technology?

Packet switching technology emerged when computer technology had developed to a certain level, and beyond direct voice communication via telephone, packet switching adds a packet header to each packet to indicate the destination address to which the packet is sent. The switch then forwards each packet to its destination based on the address flag in the packet header. This process is called packet switching.

A communication network that performs packet switching is called a packet-switched network. From the perspective of switching technology development history, data switching has evolved through circuit switching, message switching, packet switching, and integrated services digital switching. Packet switching is essentially developed on the basis of "store-and-forward." It combines the advantages of both circuit switching and message switching. Packet switching employs dynamic multiplexing technology on the line to transmit data—packets—that are divided into many small segments of a certain length. After each packet is identified, multiple data packets are transmitted simultaneously over a single physical line using dynamic multiplexing technology. Data from the calling user is temporarily stored in the switch's memory and then forwarded within the network. Upon reaching the receiving end, the packet headers are removed, and the data fields are reassembled in sequence into a complete message. Packet switching achieves higher circuit utilization than circuit switching and lower transmission delay and better interactivity than message switching.

A packet-switched network is a new type of switching network that follows circuit-switched networks and message-switched networks, primarily used for data communications. Packet switching is a store-and-forward switching method that divides user messages into packets of a certain length and performs store-and-forward on a per-packet basis. Therefore, it offers higher utilization than circuit switching and lower delay than message switching, while providing real-time communication capability. Packet switching utilizes the principle of statistical time-division multiplexing to multiplex one data link into multiple logical channels, ultimately forming an information transmission path between the calling and called users, known as a virtual circuit (V.C), to achieve packet transmission of data.

A packet-switched network has the following characteristics:

(1) Packet switching has the capability of multiple logical channels, resulting in high utilization of trunk line circuits;

(2) It enables interworking between terminals with different code formats, rates, and protocols on the packet-switched network;

(3) Due to its error detection and correction capabilities, the bit error rate of circuit transmission is extremely low;

(4) The network management functions of packet switching are powerful.

Packet switching offers two basic services: Switched Virtual Circuit (SVC) and Permanent Virtual Circuit (PVC). A switched virtual circuit is similar to a telephone circuit—when two data terminals need to communicate, they first establish a circuit (i.e., a virtual circuit) using a call setup procedure, then transmit data, and after communication ends, the virtual circuit is released using a disconnect procedure. A permanent virtual circuit is similar to a dedicated line—it provides a permanent logical connection between two terminals within the packet network during the contract period, without requiring call setup or disconnect procedures. During the data transmission phase, it operates the same as a switched virtual circuit.

A packet-switched data network consists of packet switches, a network management center, remote concentrators, packet assembly/disassembly equipment, and transmission equipment.