DA-MP Overload Control

DA-MP Overload Control (Message Priority and Color-Based DA-MP Overload Control) provides a mechanism for managing internal/local DA-MP congestion detection and control.

The DA-MP Overload Control feature tracks ingress message rate, calculates the amount of traffic that needs to be shed based on CPU congestion, and sheds that traffic based on Message Priority, Message Color, and discard policy.

Message Color is used as a means for differentiating Diameter Connections that are under-utilized versus those that are over-utilized with respect to ingress traffic - traffic from under-utilized Connections is marked green by the Per-Connection Ingress MPS Control (PCIMC) feature, while traffic from over-utilized Connections is marked yellow.

The following DA-MP Congestion Controls are associated with reducing the traffic processing load on the DA-MP when congestion is detected:

• Internal Resource Monitoring and Control

  The availability of key traffic-sensitive internal software resources (stack queues and buffer pools) is monitored in real-time against their static maximum capacity.

  When resource availability drops below engineered thresholds, alarms are generated. When resource availability is exhausted, controls are invoked to prevent over-utilization. Resource utilization KPIs and measurements provide real-time and long-term information for making decisions about system capacity and growth.

• DA-MP Overload Control

  Traffic loads, if allowed to exceed the DA-MP's engineered capacity, degrade the effective performance of the DA-MP, increase message latency, and can result in message loss. DA-MP Overload Control is responsible for reducing the traffic processing load to insure that the MP meets its performance specifications. MP Processing Overload Control monitors the Diameter Process CPU utilization of the Diameter Process.

Limitations

• DA-MP Overload Control is limited to local MP congestion management and does not address remote Diameter node congestion management.
• Automatic recovery from persistent MP or egress Connection congestion is not supported. Manual intervention is required.

Diameter Configuration for DA-MP Overload Control

The following Diameter Configuration components are used for DA-MP Overload Control:

• MP Profiles

  A DA-MP Profile is assigned to each DA-MP in the system. See the MP Profiles information in Diameter Common User's Guide.

  The assigned DA-MP Profile indicates the Engineered Maximum MPS for the DA-MP and the Message Rate Alarm Set and Clear Thresholds. These engineering-configured MP Profiles values shown on the MPs menu vary depending on the type of server used for the DA-MP.

  The following elements can be user-configured from the Diameter Common > MPs menu for use by the DA-MP Overload Control feature:

  • Congestion Level 1 Discard Percentage - The percent below the DA-MP Engineered Ingress MPS that DA-MP Overload Control polices the total DA-MP ingress MPS to when the DA-MP is in Congestion Level 1.
  • Congestion Level 2 Discard Percentage - The percent below the DA-MP Engineered Ingress MPS that DA-MP Overload Control polices the total DA-MP ingress MPS to when the DA-MP is in Congestion Level 2.
  • Congestion Level 3 Discard Percentage - The percent below the DA-MP Engineered Ingress MPS that DA-MP Overload Control polices the total DA-MP ingress MPS to when the DA-MP is in Congestion Level 3.
  • Congestion Discard Policy - The order of Message Priority and Color-based traffic segments to consider when determining discard candidates for the application of treatment during DA-MP Congestion processing. The following order is considered: Color within Priority, Priority within Color, and Priority Only.
  • Danger of Congestion Discard Percentage - The percent of total DA-MP ingress MPS above the DA-MP Engineered Ingress MPS that DA-MP Overload Control discards when the DA-MP is in danger of congestion.
• Routing Option Sets

  A Routing Option Set is a set of user-configurable routing options assigned to an ingress Diameter transaction. A Routing Option Set can be assigned to Peer Nodes and Diameter Application IDs.

  DA-MP Overload Control uses the following options:

  • Resource Exhausted Action
  • Resource Exhausted Result-Code Value
  • Resource Exhausted Vendor-ID Value
  • Resource Exhausted Error-Message Value