User Configurable Connection Pending Transaction Limiting

User-Configurable Connection Pending Transaction Limiting (UC-CPTL) provides a configurable pending transaction limit for each DSR Peer Connection, to customize the distribution of the available Pending Transaction Records on a DA-MP based on the varying deployment requirements. The limit can be configured independently for each DA-MP in the DSR.

DSR Peer Nodes have differing requirements for the maximum number of pending transactions required on the DSR:

DSR-to-Server Connections typically carry higher traffic volumes than DSR-to-Client Connections due to DSR aggregation of traffic from many client Connections to few server Connections.
A high percentage of the traffic on DSR-to-Server Connections requires Pending Transaction Records in the DSR, because Requests are the majority of the DSR egress traffic on these Connections.
A low percentage of the traffic on DSR-to-Client Connections requires Pending Transaction Records in the DSR, because Answers are the majority of the DSR egress traffic on these Connections.
DSR-to-Server Connections might encounter significant increases in offered load for a very short time immediately following network events such as MME failures or failures of redundant Servers providing the service. Handling these types of sudden increases in traffic volume can require higher Pending Transaction Limits on the Connections.

A DA-MP allocates a Pending Transaction Record for a Request message sent by the DA-MP to a Peer, and holds the PTR until the transaction completes or otherwise terminates (including Answer received and timeout termination). (An Answer message sent by a DA-MP to a Peer does not require a Pending Transaction Record.)

Multiple Active DA-MPs can route Requests to a single Connection. As a result, the maximum number of pending transactions that can exist in the DSR for a single Connection is dictated by the sum of the Pending Transaction Per Connection values enforced independently by each Active DA-MP that is routing Requests to the Connection.

The primary use of pending transaction limits for Connections on a DSR DA-MP is to prevent a small number of Connections on a DA-MP from consuming a disproportionate number of the available Pending Transaction Records on the DA-MP, which could result in limited Pending Transaction Record availability for the remaining Connections.

Diameter Configuration for the Pending Transactions Per Connection Option

The DSR provides a configurable Pending Transactions Per Connection option for each DSR Peer Connection. The value is configured in the Diameter Options of the Connection Configuration Set that is assigned to the Connection. The configured limit is enforced independently by all DA-MPs in the DSR.

The Pending Transaction Per Connection value for a Connection can be modified while the Connection is in-service. If the Pending Transactions Per Connection value is modified to a value below the current value, any pending transactions on the Connection that are above the new limit will continue to be processed and the new Pending Transactions Per Connection value will be applied only for new transactions that are initiated after the change.