Lucent Technologies 7820-0802-003 manual Normal operation, Overview of redundancy operations

Configuring Shelf-Controller Redundancy (APX 8000)

Overview of redundancy operations

The controllers next elect the controller that will be primary. The election process is based on a hierarchical list of complex criteria. The first criterion in the list is evaluated and if the criterion is found to be true, one of the controllers is made primary. If the criterion is found to be false, the next criterion in the list is evaluated.

Following is an example of the initial criteria that might be used to designate the primary controller:

1If one controller is missing, the existing (current) controller is made primary.

2If one controller is not communicating, the current controller is made primary.

3If both controllers are communicating, the controllers use the Redundancy profile’s Primary-Preference setting to determine which controller is primary.

4If Primary-Preference is set to No-Preference, the controller that last acted as the primary controller is made primary.

If a primary controller is still not determined, additional criterion are evaluated. If all election criteria fail to designate a primary controller, the controller with more resources (for example, more RAM) is made primary.

If the criteria cannot determine which controller is primary, the system selects the right controller (slot 42) to be primary and the left controller (slot 41) becomes the secondary controller.

Once a controller is elected as primary, the primary controller proceeds to load operational code. When the primary is finished loading its code, the secondary controller loads its operational image and gets a copy of the profiles.

Note: Both controllers must load the same boot and operational code version.

Normal operation

During normal operation, the two shelf controllers communicate with each other over the packet bus in a back-and-forth heartbeat, exchanging context information. The status lights on each controller indicate the following activities:

•The heartbeat (HRT) status light on each controller visually indicates that the heartbeat protocol is active by blinking on and off every 4 seconds in a regular pattern that alternates between the two controllers. In a TAOS unit that has only one shelf controller, the HRT status light flashes on for 40 milliseconds every 4 seconds.

•The primary (PRI) status light on each controller is lit if the controller is the primary and is off if the controller is secondary.

•The operational (OPR) status light is lit when the operational code is successfully loaded onto the controller.

The secondary controller does not perform controller operations unless the primary controller resets or fails, or if you change the functionality of the shelf controllers. The secondary controller’s main role is to monitor the primary and be ready to take over primary controller functions. The secondary controller maintains the current configuration and the fatal-error history log.

2-2 APX 8000/MAX TNT/DSLTNT Physical Interface Configuration Guide