Cisco Gigabit Switch Router 12008 Installation And Configuration Manual page 167

The alarm signals sent to this DB-25 connector correspond to those sent to the system alarm
LEDs on the CSC faceplate (see Figure 3-16). Thus, a critical, major, or minor alarm
condition detected in the router can trigger a simultaneous fault indication in some or all of
the following ways:
•
System alarm LEDs—The three system alarm LEDs on the CSC faceplate constitute the
standard method of alarm notification in the router.
These LEDs indicate router status at all times, but you must directly observe these LEDs
to become aware of a router alarm condition. Thus, these LEDs provide only a passive
alarm notification capability.
•
External alarm monitoring facility—By equipping your router with a telco-style
external alarm monitoring facility, you can provide a more overt indication of router
status.
For example, the same alarm signal that illuminates one of the three system alarm LEDs
on the CSC faceplate for a critical, major, or minor alarm condition is also sent to the
DB-25 connector by means of an associated alarm relay in the CSC.
An external alarm monitoring facility uses this signal to activate a visible alarm (such
as a flashing light) or an audible alarm (such as a Klaxon) that immediately alerts site
personnel to the existence of a router alarm condition.
Connecting an External Alarm Monitoring Facility
Installing a Cisco 12008 3-35