10
Overview of Cisco 2800 Series Routers
OL-5783-01
Chassis Views

Chassis Ventilation

Internal multispeed fans provide chassis cooling, controlled by an onboard temperature sensor.
The Cisco 2801 router has two fans. The Cisco 2801 router with inline power includes two additional
fans integrated with the inline power supply, for a total of four fans. The Cisco 2801 internal fans operate
at three different speeds, running at the slower speeds to conserve power and reduce fan noise at ambient
temperatures below 40oC. They operate at the highest speed in ambient temperatures above 40oC.
The Cisco 2811 router has three fans that operate at a slower speed to conserve power and reduce fan
noise at ambient temperatures below 32oC. They operate at high speed in ambient temperatures above
32oC.
The Cisco 2821 and Cisco 2851 routers have three fans that operate at a slower speed to conserve power
and reduce fan noise at ambient temperatures below 40oC. They operate at high speed in ambient
temperatures above 40oC.

Real-Time Clock

An internal real-time clock with battery backup provides the system software with time of day on system
power up. This allows the system to verify the validity of the certification authority (CA) certificate. In
the Cisco 2811, Cisco 2821, and Cisco 2851 routers, the clock and battery are permanently installed; the
battery lasts the life of the router under the operating environmental conditions specified for the router.
The Cisco 2801 router has a socketed lithium battery. This battery lasts the life of the router under the
operating environmental conditions specified for the router, and is not field-replaceable.
Note If the lithium battery in a Cisco 2801 router should fail, the router must be returned to Cisco for repair.
Although the battery is not intended to be field-replaceable, the following warning must be heeded:
Warning
There is the danger of explosion if the battery is replaced incorrectly. Replace the battery only with
the same or equivalent type recommended by the manufacturer. Dispose of used batteries according
to the manufacturer’s instructions.
Statement 1015
Chassis Views
This section contains views of the front and rear panels of the Cisco2800 series routers, showing
locations of the power and signal interfaces, module slots, status indicators, and chassis identification
labels.

Cisco 2801 Chassis

Figure 7 shows the front panel of a Cisco 2801 router. Figure8 shows the back panel.