PURPOSE: To attain miniaturization by connecting a board with a high speed switch section mounted thereon to plural circuit boards with a line control section mounted thereon so as to form one channel section module and connecting the module to a line interface section.

CONSTITUTION: A channel module SPM 10 consists of a high speed switch section 11 including a high speed switch circuit, a control circuit and a direct peripheral circuit and a line control section 12 implementing line traffic observation, operation monitor and other control. The control section 12 is controlled by a central control section 13. A line interface section 14 sending/receiving high speed communication data is connected to the control section 12 via a cable 15. The function of the interface section 14 is limited to a simple interface function. That is, the effect of the reliability and the working rate of the interface section 14 onto the entire equipment is decreased and then duplicate configuration for the interface section is not required even when redundancy is adopted and the equipment is made small.