Cisco WS-C2950-24 Hardware Installation Guide - Page 46

Hardware Features Chapter 1 Overview of the Routers Figure 1-22 Cisco 3900 Series (Non NEBS) Router Airflow 250930 SYS ACT SYS PWR1 AUX PWR1 SYS PWR2 AUX PWR2 Cisco 3900 Series Figure 1-23 Cisco 3900 Series NEBS Router Airflow SYS ACT SYS PWR1 AUX PWR1 SYS PWR2 AUX PWR2 Cisco 3900 Series 250991 Real-Time Clock Upon system power up, the internal real-time clock with battery backup provides the system software with the time of day. This allows the system to verify the validity of the certification authority (CA) certificate. The Cisco 2900 and Cisco 3900 series routers have a lithium battery. This battery lasts for the life time 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 2900 or Cisco 3900 series ISR 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 1-26 Cisco 2900 Series and 3900 Series Hardware Installation Guide OL-18712-02