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1 - 4 Transmission Control Procedures

Transmission control refers to the control that is implemented to perform efficient and accurate data transmission. The following types of controls are implemented under transmission control.

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When data transmission is performed, transmission control is implemented through each stage (i.e., phase) that is shown below.

Transmission control procedures refer to the procedures for implementing the above controls efficiently. However, since phase 1 and phase 5 are not required in the case of a leased line, phase 2 through phase 4 are defined in the transmission control procedures. Similar to phase 2 through phase 4, the method of communicating by establishing a data link is called the connection method. In contrast, the method of communicating without establishing a data link is called the connection-less method. Also, while the method of communicating by using a single data link is called the single link procedure, the method of communicating by using several parallel data links collectively as if they were a single data link is called the multilink procedure.

1-4-1 Non-Procedure (TTY Procedure)

Non-procedure (also known as TTY procedure or teletype procedure) is a method by which human beings specify the controls concerning data transmission without taking into consideration the transmission control procedures. Since only the minimum level of transmission control can be performed, it is used in low-speed lines.