---
type: Sensor Reference
title: "SNMP Optical / dBm OIDs: SFP DOM Monitoring Reference"
description: "The SNMP OIDs for optical transceivers — SFP/SFP+ DOM Rx/Tx power in dBm, temperature, bias and voltage via ENTITY-SENSOR and vendor MIBs, with examples."
resource: "https://snmp-monitoring.info/sensors/optical-dbm/"
tags: [sensors]
timestamp: 2026-07-11T00:00:00Z
---

# SNMP Optical / dBm OIDs: SFP DOM Monitoring Reference

The SNMP OIDs for optical transceivers — SFP/SFP+ DOM Rx/Tx power in dBm, temperature, bias and voltage via ENTITY-SENSOR and vendor MIBs, with examples.

## Related concepts

- Up: [SNMP Sensors & OID Catalog: Every Metric You Can Monitor](/sensors/index.md)

## Frequently asked questions

### What OID is SFP optical power?

Where a platform maps DOM into the standard table, optical power is an ENTITY-SENSOR-MIB sensor typed dBm, read from entPhySensorValue (1.3.6.1.2.1.99.1.1.1.4) with its precision applied. Many vendors instead expose it through an enterprise MIB — on Cisco, the CISCO-ENTITY-SENSOR-MIB under 1.3.6.1.4.1.9.

### What is DOM/DDM?

DOM (Digital Optical Monitoring), also called DDM (Digital Diagnostics Monitoring), is a transceiver feature that reports live diagnostics — Rx and Tx optical power, module temperature, laser bias current, and supply voltage. It lets you read an optic's health over SNMP instead of physically metering the fibre.

### How do I read Rx power in dBm?

Read the dBm-typed entPhySensorValue for the receive sensor and apply its precision — values are logarithmic and usually negative, so a raw -52 at precision 1 is −5.2 dBm. On vendor platforms, read the equivalent object from the vendor MIB (e.g. Cisco's CISCO-ENTITY-SENSOR-MIB) and apply the same value-plus-scale logic.

### Why is my Rx power too low?

A low or falling Rx power means less light is arriving than the optic needs — commonly a dirty or loose connector, a tight fibre bend, a damaged cable, or an aging laser at the far end. As Rx power approaches the transceiver's receiver-sensitivity floor, the link budget margin shrinks and errors rise, so a declining trend is worth acting on before the link flaps.

## Source

Concept generated from https://snmp-monitoring.info/sensors/optical-dbm/ — the SNMP Monitoring vendor-neutral knowledge base. Content is limited to what that page states (no external claims added here).