Shutdown

DA-MP - The Policy and Charging Application running on DA-MPs supports the DSR Application Infrastructure graceful shutdown with 5 seconds grace period. This means that when PCA is Disabled (using the Diameter > Maintenance > Applications page), the application will transition to the Degraded Operational Status for 5 seconds to allow in-flight messages to be processed without accepting any new Requests before transitioning to the Unavailable Operational Status. In the Unavailable status, neither Requests nor Answers are processed by the PCA.

SBR - Because SBR servers use the Active/Standby/Spare redundancy model, and ComAgent supports reliable transactions, there is no need for a graceful shutdown mode. Shutdown of a SBR server will cause a failover to another server in the same Server Group. (The exception is if the Server Group only has one server, as might be the case in a small demo system.)

The PCA Operational Status (Unavailable, Degraded and Available) is determined by its Admin State, Congestion Level, and the Shutdown State. The PCA calculates and maintains its own operational status and reports it to the Diameter Routing Function.

When the PCA is not processing requests (in Operational Status of Degraded or Unavailable), the Diameter Routing Function will attempt to route new Requests using the rules in the Peer Routing Tables. If the Request has no Destination-Host AVP, as would be the case for session-initiating Requests, the routing will fail and the Diameter Routing Function will respond with a 3002 DIAMETER_UNABLE_TO_DELIVER Answer.

When a Server is Stopped using the Stop function on the Status & Manage > Server page, Diameter will terminate all Diameter connections by sending a DPR and waiting for the DPA. If all DPAs have not been received within 15 seconds, Diameter begins termination of its layers and queues. If Diameter is still not shut down after another 15 seconds, the process is abruptly terminated.

To properly shut down a PCA DA-MP server,

1. Go to the Diameter > Maintenance > Applications page and Disable the PCA application.

   The Operational Status of the application will transition to Unavailable

2. Go to the Status & Manage > Server page and Stop the Server's application processes.

   After 30 seconds maintenance can proceed as necessary.

Table 7-6 shows an example of the PCA Operational Status determination where the Shutdown mode is Graceful Shutdown. The Shut down and Shutting down in the Operational Reason column indicate the states where the (Graceful) shutdown process has been completed (Shut down) and is in progress (Shutting down) respectively. While the Graceful Shutdown is in progress, the PCA continues to process the messages in its queue for a time interval that is engineering configurable.

Table 7-6 PCA Operational Status

Admin State	Congestion Level	Shutdown State	Operational Status	Operational Reason
N/A	N/A	N/A	Unavailable	Not initialized
Disabled	0 ,1, 2, 3	False	Unavailable	Shut down
Disabled	0 ,1, 2, 3	True	Degraded	Shutting down
Enabled	0 1 2	N/A	Available	Normal Available with CL_1 Available with CL_2
Enabled	3	N/A	Degraded	Congested with CL_3

SBR - Because SBR servers use the Active/Standby/Spare redundancy model, and ComAgent supports reliable transactions, there is no need for a graceful shutdown mode. Shutdown of a SBR server will cause a failover to another server in the same Server Group. (The exception is if the Server Group only has one server, as might be the case in a small demo system.)