The cooling system includes three fans at the rear of the chassis. The airflow produced by these fans keeps router components within the acceptable temperature range (see Figure 9). The speed of the fans is adjusted automatically according to the current temperature.
An air filter protects the air intake opening at the front of the chassis and must be replaced periodically. For instructions, see Replacing an Air Filter.
The Routing Engine monitors the temperature of the router components. If the maximum temperature specification, as measured at the CPU junction, is exceeded and the router cannot be adequately cooled, the Routing Engine shuts down the hardware components.
When the CPU temperature reaches 80°C (176°F), a yellow alarm is triggered. When the CPU temperature reaches 105°C (221°F), the system shuts down. There is no red alarm for temperature. You can view the CPU junction temperature using the show chassis routing-engine command. The CPU temperature runs a few degrees higher than the routing engine temperature displayed on the Monitor>Chassis page of the J-Web interface.
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On J4350 and J6350 routers that are not designed to comply with Network Building System (NEBS) criteria, the temperature at which the system shuts down is 90°C (194°F) rather than 105°C (221°F). To verify if the system is a NEBS compliant system, run the show chassis hardware command; a NEBS compliant system will contain the term NEBS in the output. |
An additional fan is part of each power supply. This fan is not regulated by the operating system.
Figure 9: Airflow Through the J4350 and J6350 Chassis
