Table of Contents

Coverage of metrics by OSI levels

graph LR L1["L1 Physical
NIC counters via system"] L2["L2 Data Link
MAC, VLAN"] L3["L3 Network
IP, IPSec ESP, GTP-U"] L4["L4 Transport
TCP/UDP/SCTP"] L5["L5 Session
GTPv2-C, IKEv2"] L6["L6 Presentation
IKEv2/IPSec encryption, EAP-AKA'"] L7["L7 Application
Diameter, service bearer ops"] Operations["Operations
KPI, SLA, Capacity"] CX["CX Level
Subscriber Experience"] L1 --> L2 --> L3 --> L4 --> L5 --> L6 --> L7 --> Operations --> CX style L1 fill:#e74c3c,color:#fff style L2 fill:#e67e22,color:#fff style L3 fill:#f39c12,color:#fff style L4 fill:#2ecc71,color:#fff style L5 fill:#1abc9c,color:#fff style L6 fill:#3498db,color:#fff style L7 fill:#9b59b6,color:#fff style Operations fill:#34495e,color:#fff style CX fill:#2c3e50,color:#fff

Detailing metrics by level

OSI model:

Level Metrics Examples
L1/L2 Physical / Data Link - Covered by a separate node_exporter or equivalent at the OS level (not included in the ePDG metrics list)
L3 Network / IPSec tunnels 3 epdg_gtpu_packets_total, epdg_gtpu_bytes_total, epdg_gtpu_errors_total — GTP-U data plane
L4 Transport 1 epdg_network_connection_status — TCP connections to nodes (PGW/AAA/HSS)
L5 Session 3 epdg_session_ike_sa_total, epdg_session_child_sa_total, epdg_session_gtp_sessions_total
L6 Presentation/Security 3 epdg_ikev2_messages_total, epdg_ikev2_request_duration_seconds, epdg_ikev2_errors_total — IKEv2/IPSec encryption and EAP-AKA authentication
L7 Application 9 epdg_diameter_* (SWm/SWx/S6b, 5 metrics), epdg_gtp_* (GTPv2-C, 4 metrics)

Operator level:

Level Metrics Examples
Operations 11 epdg_service_availability, epdg_service_uptime_seconds, epdg_app_* (3), epdg_system_* (4), epdg_config_* (2)
Customer Experience 3 epdg_service_attach_duration_seconds p95, epdg_service_attach_total (success rate), epdg_ikev2_request_duration_seconds p99

Level 9: Quality of VoWiFi service perception

QoE indicator Source metrics Interpretation
VoWiFi connection time epdg_service_attach_duration_seconds p95 > 3 seconds — subscriber notices delay when switching to WiFi
Continuity of service epdg_session_ike_sa_total delta Mass discharge > 50 IKE SA = accessibility issue
Authentication success ePDG_High_Attach_Failure_Rate alert rate > 5% = HSS/AAA node problem
Delayed appointment bearer epdg_gtp_request_duration_seconds{msg=create-session} p99 > 500 ms — delayed availability of voice channel
GTP-U tunnel epdg_gtpu_errors_total rate / epdg_gtpu_packets_total > 0.1% = degradation of voice quality
IKEv2-reliability epdg_ikev2_errors_total by type NO_PROPOSAL_CHOSEN / AUTHENTICATION_FAILED — problems with certs / UE