Troubleshooting Guide

Chapter 18: Layer 1 troubleshooting
Use this section to help you troubleshoot Layer 1 (physical layer) problems.
Troubleshooting fiber optic links
About this task
You can troubleshoot fiber optic links to ensure that the optical transmitters and receivers operate
correctly, and to determine if a receiver is saturated, or does not receive enough power.
To troubleshoot optical links and devices, you can use Digital Diagnostic Monitoring (DDM), as well
as published optical specifications.
For more information about Small Form Factor Pluggable (SFP) transceivers and SFP plus (SFP+)
transceivers, see Installing Transceivers and Optical components on VSP Operating System
Software, NN47227-301.
Important:
Avaya recommends the use of Avaya branded SFP and SFP+ transceivers as they have been
through extensive qualification and testing. Avaya will not be responsible for issues related to
non-Avaya branded SFP and SFP+ transceivers.
Procedure
1. Measure the SFP or SFP+ transmit power.
2. Compare the measured transmit power with the specified launch power.
The values are similar. If the measured power is far below the specified value, a faulty
transmitter is a possible cause.
3. Compare the measured transmit power for the near-end optical device to the measured
transmit power for the far-end device.
Large differences can mean that the optical devices are mismatched (that is, -SX versus -
LX).
4. Measure the receive power at each end of the link.
5. Compare the receive power to the transmit power.
• For short fiber links, the transmit and received power are similar (after taking into
consideration connection losses).
January 2017 Troubleshooting 142
Comments on this document? [e-mail]