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🧪 Lab 04 · Programmatic Telemetry & State Parsing (gNMI / pygnmi)

✅ Validated on gNMI (gRPC Network Management Interface) & Python pygnmi.

Time: ~45 minutes · Tools: gNMI, Protocol Buffers (protobuf), OpenConfig YANG

🧠 Technology Deep Dive: gNMI vs. Legacy SNMP

Traditional network monitoring relies on SNMP (Simple Network Management Protocol), which polls devices periodically over UDP 161. SNMP is CPU-intensive, unencrypted, and slow to reflect link flaps.

gNMI (gRPC Network Management Interface) is a unified RPC protocol defined by the OpenConfig consortium: - Transport: HTTP/2 over TLS (TCP 6030 or TCP 50051). - Data Encoding: Google Protocol Buffers (protobuf) or JSON. - YANG Modeling: Uses OpenConfig YANG paths (e.g. /interfaces/interface[name=Ethernet1]/state/oper-status). - Modes: Supports Get, Set, and Subscribe (streaming telemetry).

💻 Querying Device State with Python (pygnmi)

from pygnmi.client import gNMIclient

host = ("172.20.20.33", "6030")
path = ["openconfig-interfaces:interfaces/interface[name=Ethernet1]/state"]

with gNMIclient(target=host, username="admin", password="password", insecure=True) as c:
    result = c.get(path=path)
    print(result)

{
  "name": "Ethernet1",
  "admin-status": "UP",
  "oper-status": "UP",
  "counters": {
    "in-octets": 1048293,
    "out-octets": 948201
  }
}

✅ DONE when pygnmi retrieves live OpenConfig interface state over gRPC.