1-3-4 Switching Method

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1-3-4 Switching Method

A switching method is used to determine how to transmit data to the other party through a line, such as a public line, for which the communication partner is not identified. Therefore, there is no need to consider the switching method in a leased line service that provides leased lines that are directly linked to the communication partner in a fixed manner.

(1) Circuit switching method

The circuit switching method is a method that has the similar configuration to a public telephone network, and transmits data by setting a physical communication channel with circuit switching equipment each time a data transmission request occurs. The network of the

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circuit switching method is called a circuit switched network, and a circuit switching service refers to the service that provides a communication environment by connecting the users within the network with circuit switching equipment.

Original Switching Method source table or explanation box, preserving its complete original arrangement, labels and values. Source text: [Characteristics of circuit switching method] • This is suitable for batch transmission of high-density/large amount of data. • The communication equipment at the transmitting side and the receiving side must have the same communication speed. • No transmission delay occurs within the network. — p. 301 · Enlarge

(2) Store-and-forward switching method

The store-and-forward switching method is used to transmit data via store-and-forward switching equipment on the basis of the address that is appended in each data unit, without setting a physical communication channel for the transmission destination. In the store-and-forward switching method, the optimum relay line is determined according to the congestion of the communication line. This is because when the traffic (i.e., data) that flows across the communication line becomes too high, the transmission efficiency declines, and a delay occurs easily.

Store-and-forward packet paths, with the original a, b and c data units and intermediate switching devices. Source text: Figure 5-3 Image of the store-and-forward switching method — p. 301 · Enlarge

The store-and-forward switching method has the following three kinds of typical transmission techniques and services.

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(1) Packet switching (Packet switching service) This is a method that divides the transmission data into units called packets. A header in which the address of the other party is recorded is appended to the packet. Generally, a PT (Packet mode Terminal) with a built-in PAD (packet assembly and disassembly) function is used to connect to the packet switched network. However, even in the case of NPT (Non-Packet mode Terminal), a connection can be established by providing the PAD function in the switching equipment.

(2) Frame relay (Frame relay service) This is a method that divides the transmission data into frame units of a variable length, and may be thought of as a packet switching method with a high speed. An address part including a DLCI (Data Link Connection Identifier) that represents the other party is appended to the frame. A connection is established to the frame relay network by a FRAD (FRame Assembly/Disassembly device) that performs assembly and disassembly of the frame.