WeOS
5.20.1

# SFP DDM Guide

- Introduction
- Description
- TX Power
- RX Power
- Temperature
- BIAS current
- Voltage

## Introduction

In this chapter you will learn about:

- how the SFP digital diagnostic monitoring (DDM) is managed in WeOS
- where to find the DDM parameters
- which DDM parameters are available for monitoring
- a description of the DDM parameters

## Descriptionhttps://ta.snia.org/higherlogic/ws/public/download/294/SFF-8472.PDF) The DDM parameters can be monitored in WeOS CLI or SNMP. In CLI the SFP information is located in port status context, e.g. ‘show port ethN’ SNMP OID for the diagnostics are x.xx.x.x.x.x WeOS provides diagnostic information for the following DDM parameters which are read from the SFP on demand when you ask for them.

## TX power

Measures the optic power when transmitting, which can be used for detecting a deteriorating link.(see 3) The accuracy is better than +/-3dB and the total range of -40 to +8.2 dBm (0–6.5535 mW) in SNMP reported in 0.01 dBm steps.

## RX power

Measures the optic power when receiving, which can be used for detecting a deteriorating link. The accuracy is better than +/-3dB and the total range of -40 to +8.2 dBm (0–6.5535 mW) in SNMP reported in 0.01 dBm steps.

## Temperature

The temperature of the SFP should be very close or equal to the temperature of the unit. The temperature accuracy is better than 3 degrees Celsius (°C) and the total range of -128°C to +128°C.

## Bias current

The transmitting bias current can be used to determine how fast an SFP is aging. The accuracy is better than +/- 10% and the total range of 0 - 131 mA in SNMP reported in 1 uA steps.

## Voltage

The voltage should always be 3.3V since the SFP’s power supply line is the same as the unit. The accuracy is better than +/-3% and the total range of 0–6.55 V in SNMP reported in 1 mV steps.

3 By comparing the TxPower on a unit with the RxPower on the unit it is connected to, the user can find out the amount of “signal strength” that is lost over the optic link. When the gap between TxPower and RxPower is increasing, the optic link’s capability to transfer the signal decreases.