Which of the following measures are effective to keep good heat dissipation for an IDU?

Effective heat dissipation for an Indoor Unit (IDU) relies on maintaining adequate airflow.
A. Installing an external fan on the cabinet door actively forces air circulation, significantly improving the removal of hot air from the cabinet.
B. Reserving 1U of space above and below the IDU is a standard installation practice that facilitates natural convection, allowing hot air to rise and preventing heat transfer between adjacent devices.
D. Opening the cabinet door provides maximum ventilation by allowing unrestricted exchange with the ambient room air, which is a highly effective, if sometimes temporary, method to prevent overheating.

C. Opening vacant slots is incorrect. Filler panels must be installed in all vacant slots to maintain the designed internal airflow path, ensuring that cool air is directed over critical components and preventing air from short-circuiting.

1. Huawei OptiX RTN 950 Radio Transmission System Installation Guide.

Reference for B: In the chapter "Installation Preparations

" the section on "Cabinet Requirements" typically specifies that for proper heat dissipation

a space of at least 1U (44.45 mm) should be left above and below the chassis.

Reference for C: The chapter "Installing the Chassis and Boards

" under the section for installing boards

explicitly states that filler panels must be installed in any unused slots to ensure proper ventilation and dust protection

as they are critical for maintaining the designed airflow.

2. Huawei NE40E Universal Service Router Hardware Description.

Reference for A & D: The section on "Site Environment Requirements" details heat dissipation and ventilation. It discusses the total heat dissipation of the chassis and the need for a good ventilation system in the cabinet or room

which can include cabinet fans (A). It also implicitly supports (D) by emphasizing that insufficient airflow will cause the system to overheat

a condition that opening the door directly alleviates.