Chapter 20: Layer 1 Troubleshooting; Troubleshooting Fiber Optic Links - Avaya 8800 Troubleshooting Manual

Chapter 20: Layer 1 troubleshooting

Use this section to help you troubleshoot Layer 1 (physical layer) problems.

Troubleshooting fiber optic links

To troubleshoot optical links and devices, you can use Digital Diagnostic Monitoring (DDM),
as well as published optical specifications.
You can troubleshoot fiber optic links to ensure that the optical transmitters and receivers are
operating correctly, and to determine if a receiver is saturated, or not receiving enough
power.
For small form factor pluggable (SFP) transceiver, 10 Gigabit SFP (XFP) transceiver, and
Gigabit Interface Converter (GBIC) specifications, see Avaya Ethernet Routing Switch
8800/8600 Installation — SFP, XFP, GBIC and OADM Hardware Components,
NN46205-320.
Procedure steps
1. Measure the SFP, XFP, or GBIC transmit power.
2. Compare the measured transmit power with the specified launch power.
3. Compare the measured transmit power for the near-end optical device to the
4. Measure the receive power at each end of the link.
5. Compare the receive power to the transmit power.
Troubleshooting
The values should be similar. If the measured power is far below the specified value,
then a faulty transmitter is a possible cause.
measured transmit power for the far-end device.
Large differences could mean that the optical devices are mismatched (that is, -SX
versus -LX).
• For short fiber links, the transmit and received power should be similar (after
taking into consideration connection losses).
• For long fiber links, the transmit and received power should be similar (after
taking into consideration connection losses and fiber attenuation).
Large differences could mean a damaged fiber or dirty or faulty connectors. It could
also mean that the link does not use the right type of fiber (single mode or
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