MX304 Cooling System

Fan Modules

The chassis monitors the temperature of the router components. When the router is operating normally, the fans function at a lower 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 the router by disabling output power from each power supply.

The router has three fan modules that install at the rear of the router. Each fan tray uses two 80 mm x 80 mm counter rotating fans. The fan modules are hot-swappable and hot-removable field-replaceable units (FRUs) (see Figure 1 and Figure 2).

Note:

When the chassis is online, you can replace one fan at a time. See Table 1 for fan removal time. To avoid disturbing the air flow and cooling, don't operate the chassis when a fan module is removed.

Table 1: Fan Removal

Ambient Temperature	Traffic	Fan Removal Tray Time (Seconds)
25°C (77°F)	100%	115
40°C (104°F)	100%	40

Airflow

The router has a front-to-back (AIR OUT) cooling system (see Figure 3). Cool air is pulled through the vents on the front the chassis and hot air exhausts through the vents on the rear of the chassis.

Air Filter Unit

The air filter unit consists of three parts:the outer filter cover, the air filter, and the inner cage (see Figure 4). The air filter sits right inside the outer filter cover and the inner cage. The air filter unit is installed into the cable management brackets, and are held tightly by captive screws.

Table 2: Air Filter

Product Number	Description	Oderable
JNP-FLTRDR-2RU	JNP304 Air filter assembly	Spare
JNP-AIRFLTR-2RU	Air Filter	Spare

Power Supply Cooling System

The self-cooling power supplies and exhaust vents are in the rear of the router (to the left of the chassis).