Technical Documentation
T320 Cooling System Description
The cooling system components work together to keep all router components within the acceptable temperature range. The host subsystem monitors the temperature of the router components. When the router is operating normally, the fans function at lower than full speed. If a fan fails or the ambient temperature rises above a threshold, the speed of the remaining fans is automatically adjusted to keep the temperature within the acceptable range. If the ambient maximum temperature specification is exceeded and the system cannot be adequately cooled, the Routing Engine shuts down some or all of the hardware components.
Airflow
Figure 1 shows the airflow through the router.
Figure 1: Airflow Through the T320 Chassis
Fan Trays
 | Note: The standard fan trays and quiet fan trays are not interchangeable with each other. All fans in the chassis must be either standard fan trays or quiet fan trays. |
The cooling system contains the following fan trays:
One rear fan tray cools the components installed in the rear card cage (the Routing Engines, control boards, SCGs, and the SIBs). The T320 router supports the following types of rear fan trays:
- The standard rear fan tray with five blowers (EOL) is supported by Junos OS 5.4 and later. It has no label and is not interchangeable with the standard front fan trays.
- The quiet rear fan tray, labeled REAR FANTRAY FAN-R-S and supported by Junos OS 11.1 and later,, contains eight fans and is not interchangeable with the quiet front fan trays.
One upper front fan tray and one lower front fan tray that cool the components installed in the front card cage (the FPCs, PICs, CIP, and midplane). The T320 router supports the following front fan trays:
- The upper and lower standard front fan trays, each of which contain six fans and have no labels. Both standard fan trays are interchangeable with each other.
- Each quiet front fan tray contains four fans, as indicated
by the four fan icons on the faceplate.
Note: The quiet upper front fan tray and quiet lower front fan tray are not interchangeable with each other. In addition to the labels, the quiet upper fan tray also has an upward pointing arrow above the four fan icons on the faceplate.
The quiet upper front fan tray is labeled FAN-T-FTOP-S and UPPER FANTRAY (see Figure 2).
Figure 2: Quiet Upper Front Fan Tray
The quiet lower front fan tray is labeled FAN-T-FBOT-S and LOWER FANTRAY (see Figure 3).
Figure 3: Quiet Lower Front Fan Tray
All fan trays are hot-insertable and hot-removable.
Air Filters
The cooling system contains a front air filter and a rear air filter. All air filters are hot-insertable and hot-removable.
Power Supply Cooling System
Each DC power supply contains one fan that cools that power supply.
