Diameter Rx Interface¶

Overview¶

The Diameter Rx interface is used for policy control between the Application Function (AF) and the Policy and Charging Rules Function (PCRF). It enables applications to request QoS resources and provides service awareness to the policy control system.

Interface Specifications¶

Rx Interface (3GPP TS 29.214)¶

Application ID: 16777236
Vendor ID: 10415 (3GPP)
Commands:
AA-Request (AAR)
AA-Answer (AAA)
Re-Auth-Request (RAR)
Re-Auth-Answer (RAA)
Session-Termination-Request (STR)
Session-Termination-Answer (STA)
Abort-Session-Request (ASR)
Abort-Session-Answer (ASA)

Message Flows¶

Basic Session Flow¶

sequenceDiagram
    participant AF as Application Function
    participant PCRF as Policy Control Function

    AF->>PCRF: AAR (Initial Request)
    PCRF->>AF: AAA (Initial Answer)
    Note over AF,PCRF: Service Delivery
    PCRF->>AF: RAR (Policy Update)
    AF->>PCRF: RAA (Update Response)
    Note over AF,PCRF: Service Modification
    AF->>PCRF: STR (Session Termination)
    PCRF->>AF: STA (Termination Response)

Implementation Examples¶

Session Establishment¶

from telcoapi.diameter import rx

# Initialize Rx client
client = rx.RxClient(
    host="af.example.com",
    realm="example.com",
    destination_host="pcrf.example.com",
    destination_realm="example.com"
)

# Send AA-Request
aar = client.create_aar(
    session_id="session123",
    subscription_id="123456789",
    media_component=[{
        "media_component_number": 1,
        "media_type": "AUDIO",
        "codec_data": "PCMU",
        "bandwidth": {
            "upstream": 64000,
            "downstream": 64000
        }
    }]
)

response = client.send_aar(aar)
print(f"Session establishment response: {response}")

Policy Update Handling¶

# Handle Re-Auth-Request
@client.on_rar
def handle_rar(rar):
    # Process policy updates
    if rar.specific_action == "INDICATION_OF_LOSS_OF_BEARER":
        # Handle bearer loss
        notify_application_of_bearer_loss()

    # Send Re-Auth-Answer
    raa = client.create_raa(
        session_id=rar.session_id,
        result_code=2001  # DIAMETER_SUCCESS
    )
    client.send_raa(raa)

Session Termination¶

# Send session termination
str_request = client.create_str(
    session_id="session123",
    termination_cause="DIAMETER_LOGOUT"
)

response = client.send_str(str_request)
print(f"Session termination response: {response}")

Vendor Integration¶

Ericsson PCRF Integration¶

# Ericsson PCRF configuration
client.set_vendor_config({
    "vendor_id": 193,    # Ericsson vendor ID
    "product_name": "Ericsson PCRF",
    "firmware_revision": 1,
    "custom_avps": [
        {"code": 9001, "name": "Ericsson-Service-Awareness"},
        {"code": 9002, "name": "Ericsson-QoS-Profile"}
    ]
})

Huawei PCRF Integration¶

# Huawei configuration
client.set_vendor_config({
    "vendor_id": 2011,   # Huawei vendor ID
    "product_name": "Huawei PCRF",
    "firmware_revision": 1,
    "custom_avps": [
        {"code": 7001, "name": "Huawei-Media-Policy"},
        {"code": 7002, "name": "Huawei-Bandwidth-Policy"}
    ]
})

Error Handling¶

Common Error Scenarios¶

Result Code	Name	Description	Action
5001	DIAMETER_ERROR_USER_UNKNOWN	Unknown user	Verify user identity
5002	DIAMETER_ERROR_INVALID_SERVICE_INFORMATION	Invalid service info	Check media components
5003	DIAMETER_ERROR_FILTER_RESTRICTIONS	Filter error	Review filter rules
5004	DIAMETER_ERROR_REQUESTED_SERVICE_NOT_AUTHORIZED	Unauthorized service	Check authorization

Error Handling Example¶

from telcoapi.diameter.exceptions import RxError

try:
    response = client.send_aar(aar_request)
except RxError as e:
    if e.result_code == 5002:  # INVALID_SERVICE_INFORMATION
        # Modify service information and retry
        modify_service_info(e.request)
        retry_request(e.request)
    else:
        # Log error and take appropriate action
        logger.error(f"Rx interface error: {e}")

Monitoring¶

Key Metrics¶

Session Establishment Success Rate
Policy Update Success Rate
Average Response Time
Active Sessions Count
QoS Modification Rate

Monitoring Example¶

# Register monitoring callbacks
@client.on_metrics
def collect_rx_metrics(metrics):
    print(f"Session success rate: {metrics.success_rate}%")
    print(f"Average response time: {metrics.avg_response_time}ms")
    print(f"Active sessions: {metrics.active_sessions}")

Configuration Examples¶

Basic Configuration¶

rx_interface:
  host: "af.example.com"
  realm: "example.com"
  port: 3868
  application_id: 16777236
  vendor_id: 10415
  security:
    tls_enabled: true
    certificate: "/path/to/cert.pem"
    private_key: "/path/to/key.pem"
  peers:
    - host: "pcrf1.example.com"
      realm: "example.com"
      port: 3868
      role: "server"
    - host: "pcrf2.example.com"
      realm: "example.com"
      port: 3868
      role: "server"

Advanced Configuration¶

rx_interface:
  host: "af.example.com"
  realm: "example.com"
  port: 3868
  application_id: 16777236
  vendor_id: 10415
  vendor_specific:
    vendor_id: 193
    product_name: "Example AF Client"
    firmware_revision: 1
  security:
    tls_enabled: true
    certificate: "/path/to/cert.pem"
    private_key: "/path/to/key.pem"
    cipher_suites:
      - "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384"
      - "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256"
  routing:
    strategy: "round_robin"
    failover_enabled: true
    retry_count: 3
    timeout: 5000
  session_management:
    cleanup_interval: 300
    max_sessions: 10000
    session_timeout: 3600
  peers:
    - host: "pcrf1.example.com"
      realm: "example.com"
      port: 3868
      role: "server"
      weight: 100
    - host: "pcrf2.example.com"
      realm: "example.com"
      port: 3868
      role: "server"
      weight: 100

Best Practices¶

Implement proper session management
Handle policy updates promptly
Use secure transport (TLS)
Implement proper failover
Monitor session states
Handle media component updates
Implement QoS monitoring
Use appropriate timeouts
Handle multiple media streams
Implement proper event notification