External Diameter Gateway Overview

External Diameter Gateway (EDGW) is a cloud native Diameter gateway that enables communication for the Rf, Gz, Gy / Ro, Gx, Rx, and Sy Diameter interfaces. It runs as a stateless pod and converts Diameter protocol messages to MDCs that are sent to MATRIXX Engine.

Important: In a multi-domain environment, each domain must have its own EDGW.
EDGW acts as a Diameter client when sending outbound Diameter messages (RAR, SNR, ASR, STR). It uses source host and realm information in outgoing MDCs to identify to which TCP/IP connection each message must be sent. Figure 1 shows how incoming Diameter messages are handled by MATRIXX.
Figure 1. External Diameter Gateway Communication
External Diameter Gateway converts Diameter messages to MDCs and sends them over TCP through TRA to MATRIXX Engine.

EDGW is not required for the Gz and Rf interfaces. MATRIXX supports Diameter Rf/Gz offline charging sessions using Diameter Accounting-Request (ACR) messages and Accounting-Answer (ACA) messages. The Diameter Gz interface is used for offline charging for data service from a Policy and Charging Enforcement Function (PCEF) client to an Offline Charging System (OFCS) (MATRIXX). The Diameter Rf interface is used for offline charging for voice and messaging services from AS, SMSC, and MMSC clients to an OFCS (MATRIXX). For more information about offline rating, see the discussion about rating in MATRIXX Pricing and Rating.

The Gy reference point enables communication between MATRIXX Charging Application Online Charging System (OCS) and a PCEF. The Ro interface is between an IMS entity and MATRIXX Charging Application.

The Diameter Sy reference point connects the MATRIXX Charging Application and an external Policy and Charging Rules Function (PCRF).

The Gx reference point enables MATRIXX Engine to communicate with a PCEF when a policy session is initiated. External Diameter Gateway maps incoming Diameter Gx requests to MDCs that are sent to the Traffic Routing Agent that forwards the MDCs to the MDC Gateway and returns a response with the policies, result codes, and so forth.

The Rx reference point enables MATRIXX Policy Application to gather data from an external Application Function (AF), which uses the data to construct and publish PCC and QoS rules over the Gx interface to an external Policy and Charging Enforcement Function (PCEF).

EDGW uses the Attribute Value Pair (AVP) elements in the diameter_dictionary.xml file to define the AVPs supported by MATRIXX for the interfaces supported by EDGW. Each avp element completely defines one AVP. Most MATRIXX implementations customize the Diameter Dictionary with custom MDCs. This custom dictionary file is used in the CI/CD pipeline to create the custom EDGW. For more information about building using the CI/CD pipeline, see the discussion about EDGW CI/CD pipeline in MATRIXX Diameter Integration.

Logging

All MATRIXX components produce log output used for debugging any issues that arise in the system. In a Kubernetes environment, you can view and search logs without having to log in to individual Kubernetes pods. To persist logs in a cloud native environment, use a log aggregator, which collects log output and sends it to persistent storage where it can be queried. For information about logging, including overriding default behavior so that all log output is redirected to STDOUT, see the discussion about aggregating logs in MATRIXX Monitoring and Logging.

OpenTelemetry

EDGW supports OpenTelemetry to provide a set of standardized vendor-agnostic SDKs, APIs, and tools for ingesting, transforming, and sending data to an observability back-end. For information about integrating EDGW with OpenTelemetry, see the discussion about OpenTelemetry configuration in MATRIXX Diameter Integration and the OpenTelemetry documentation.

For information about installing OpenTelemetry, see the OpenTelemetry documentation.