Contents
- 1 Command Syntax — display ont optical-info Explained
- 2 Reading the Output — Summary Mode (All ONTs)
- 3 Reading the Output — Detailed Mode (Single ONT)
- 4 Optical Power Thresholds — What’s Normal, What’s a Problem
- 5 Step-by-Step Troubleshooting Using display ont optical-info
- 6 Related Huawei OLT Commands — Complete Diagnostic Toolkit
- 7 Common Issues Found with display ont optical-info — and How to Fix Them
- 8 Using display ont optical-info for Proactive Daily Monitoring
- 9 Frequently Asked Questions
- 10 Quick Reference Cheat Sheet SAVE THIS
- 11 Conclusion
If you’re an ISP engineer working on a Huawei OLT and you need to quickly check why an ONT is flapping, underperforming, or going offline — display ont optical-info is the single most powerful diagnostic command in your toolkit. It gives you real-time optical transceiver data for any ONT directly from the OLT CLI, without a fiber meter, without a site visit, and within seconds. This guide breaks down every output field, every command variant, and what every reading means — with real examples and actionable fix steps.
The display ont optical-info 0 1 command on Huawei OLT retrieves live optical health data from a specific ONT — its receive power, transmit power, what the OLT itself is measuring from that ONT, laser bias current, temperature, and voltage. Understanding this output is the difference between a 10-minute fix and a 3-hour truck roll that shouldn’t have happened.
This guide is for ISP technicians, GPON engineers, fiber network operators, and NOC teams managing Huawei OLT platforms including the MA5800, MA5600T, MA5680T, and MA5683T series.
Command Syntax — display ont optical-info Explained
Before looking at any output, let’s understand exactly what you’re running and how to form the command correctly for any scenario.
Where:
port-id = the PON port number on the current GPON interface (usually 0–7)
ont-id = the ONT’s ID number (0–127 for GPON), or all to check every ONT on that port
You must first enter the GPON interface context before the command is valid. Here’s the full navigation:
Command Variants at a Glance
Single ONT Check
display ont optical-info 0 1Detailed output for ONT ID 1 on port 0. Full field-by-field breakdown including alarm thresholds.
All ONTs — Quick Overview
display ont optical-info 0 allSummary table showing RX, TX, OLT Rx, Temp, Voltage, Current for all ONTs on the port at once.
Global View (No Interface)
display ont optical-info 0/1/0 1Run from any mode without entering interface context. Useful for NOC scripts and multi-port checks.
Detailed Single (Full Thresholds)
display ont optical-info 0 0Shows per-parameter alarm and warning thresholds alongside current values — essential for baseline comparison.
display ont optical-info 0 all first as your wide-angle diagnostic. It immediately shows you which ONTs have abnormal power levels across the entire port so you can triage quickly. Then zoom in with display ont optical-info 0 {id} for the problematic ones.Reading the Output — Summary Mode (All ONTs)
When you run display ont optical-info 0 all, you get a compact table. Here’s what a real output looks like — and what every column means:
In seconds you can see that ONT 11 is critical (below -27 dBm), ONTs 10 and 17 are marginal and need attention, and the rest are healthy. This is your daily health-check command.
Summary Column Definitions
| Column | What It Measures | Normal Range | Direction |
|---|---|---|---|
| ONT Rx power | Signal the ONT receives from OLT (downstream) | -8 to -27 dBm | OLT → ONT |
| ONT Tx power | Signal the ONT transmits toward OLT (upstream) | +0.5 to +5 dBm | ONT → OLT |
| OLT Rx power | What the OLT’s receiver actually sees from this ONT | -8 to -30 dBm | ONT → OLT (measured at OLT) |
| Temperature | ONT optical module temperature | 0°C to 70°C | Internal sensor |
| Voltage | ONT module supply voltage | 3.10V to 3.50V | Internal sensor |
| Current (mA) | Laser bias current (indicates laser health) | 5 to 25 mA | Internal sensor |
Reading the Output — Detailed Mode (Single ONT)
Running display ont optical-info 0 1 for a specific ONT gives you the full verbose output with alarm and warning thresholds for every parameter. This is your deep-dive diagnostic view.
Every Output Field — Explained in Plain English
| Field | Meaning | Good Value | Action if Bad |
|---|---|---|---|
Module type | PON technology type (GPON, EPON) | GPON / EPON | Wrong module type — check ONT compatibility |
Module sub-type | Optical class defining power budget | CLASS B+ or C+ | Mismatched class = limited reach/power |
Vendor name | Optical transceiver manufacturer | HWTC, Hisense, Broadex, etc. | Unknown vendor = check compatibility |
Rx optical power | Downstream signal strength at ONT photodetector | -8 to -27 dBm | Below -27: fiber loss issue → check path |
Tx optical power | Upstream signal strength from ONT laser | +0.5 to +5 dBm | Low Tx: aging/failing ONT laser → replace ONT |
Laser bias current | Electrical current driving the laser diode | 10 to 25 mA | Above 30 mA: laser aging → plan replacement |
Temperature | Optical module operating temperature | 0°C to 70°C | Above 75°C: ventilation issue or failing module |
Voltage | Optical module supply voltage | 3.10V to 3.50V | Out of range: power supply issue at ONT |
OLT Rx ONT optical power | What OLT actually receives from this ONT upstream | -8 to -30 dBm | Very low: fiber issue in upstream path |
CATV Rx optical power | CATV optical signal level (triple-play ONTs only) | >-6 dBm (if used) | Low: CATV splitter or RF overlay issue |
alarm threshold | The OLT will generate an alarm if value crosses this | Depends on ONT model | [-,-] means thresholds not set — configure them |
[-,-], it means they haven’t been configured. For production networks, always configure Rx power alarm thresholds with ont alarm-profile so the OLT auto-alerts you when any ONT approaches the danger zone — before subscribers complain.Optical Power Thresholds — What’s Normal, What’s a Problem
This is the section you’ll reference most often. GPON Class B+ (the most common standard for ISP deployments on Huawei OLTs) has well-defined power ranges. Memorize these or bookmark this page.
📊 ONT Rx Power Level Scale (GPON Class B+)
| Parameter | Excellent | Acceptable | Marginal ⚠️ | Critical 🚨 |
|---|---|---|---|---|
| ONT Rx power | -8 to -20 dBm | -20 to -24 dBm | -24 to -27 dBm | Below -27 dBm |
| ONT Tx power | +2 to +5 dBm | +0.5 to +2 dBm | Below +0.5 dBm | Below -1 dBm |
| OLT Rx ONT power | -8 to -22 dBm | -22 to -27 dBm | -27 to -30 dBm | Below -30 dBm |
| Temperature | 25°C to 55°C | 55°C to 70°C | 70°C to 80°C | Above 80°C |
| Voltage | 3.20V to 3.40V | 3.10V to 3.20V | 3.00V to 3.10V | Below 3.00V or above 3.60V |
| Laser bias current | 10 to 20 mA | 20 to 25 mA | 25 to 30 mA | Above 30 mA or below 5 mA |
display board 0/1 to confirm which class you’re operating.Step-by-Step Troubleshooting Using display ont optical-info
Here’s the systematic workflow experienced GPON engineers use when an ONT is offline or performing poorly. Follow this order — it moves from fastest/easiest to most complex.
Confirm the ONT Is Registered and Its Run State
Before running optical-info, verify the ONT actually exists in the OLT database and check its current state. Optical info is only available for online ONTs.
display ont optical-info will return no data or N/A. Fix the offline issue first (see our Huawei ONT Offline Fix Guide), then use optical-info for fine-tuning.Run the Wide-Angle Port Scan
Scan all ONTs on the affected port to immediately identify which ONTs have power issues and prioritize your work.
Deep-Dive the Problem ONT
Now get the full detailed output for the specific ONT with issues — with all thresholds visible.
Diagnosis from this output: The ONT hardware itself is aging (high laser bias current at 31 mA with temperature at 59°C). The Rx power being below threshold indicates additional fiber loss. This needs both a fiber path check AND an ONT replacement.
Cross-Reference with ONT Info and Alarm History
Combine optical data with the ONT’s administrative state and alarm history to build the complete picture.
Correlate: Is It the Fiber or the ONT?
Use the optical data to determine root cause before dispatching a technician. This decision matrix saves truck rolls.
| What optical-info shows | Probable Root Cause | Fix |
|---|---|---|
| Low Rx, Normal Tx, Normal OLT Rx | Fiber attenuation in downstream path | Check downstream splitter ports, connectors |
| Low Rx, Low OLT Rx, Normal Tx | Fiber loss in both directions — likely feeder/splitter | OTDR trace, check splitter and feeder fiber |
| Normal Rx, Low Tx, High Laser Current | Aging or failing ONT laser module | Replace ONT hardware |
| Low Rx, No OLT Rx (N/A) | ONT offline — fiber cut or no signal | Check ONT info first, then trace fiber |
| High temperature (>75°C), Low Tx | Overheating ONT laser | Improve ONT ventilation or replace module |
| Voltage out of range | ONT power supply issue | Check ONT adapter and power input |
| Rx fluctuating (run command multiple times) | Intermittent connector or fiber bend | Inspect and re-seat all connectors in path |
| All ONTs on port weak simultaneously | OLT PON port SFP issue or first-stage splitter | Check OLT port state, reseat SFP, check feeder |
Reboot the ONT Remotely If Needed
If optical levels look acceptable but the ONT is stuck or misbehaving, a remote reboot often resolves it without a site visit.
Monitor for Stability Over Time
Run display ont optical-info several times across different times of day — especially morning/night when temperature swings can push borderline ONTs offline.
Related Huawei OLT Commands — Complete Diagnostic Toolkit
The display ont optical-info command works best when combined with these companion commands for full-picture troubleshooting.
| Command | What It Shows | When to Use |
|---|---|---|
display ont info {port} {id} | ONT run state, config state, SN, auth type, last down cause | First command — always check this before optical-info |
display ont info summary {port} | Summary of all ONT states on a port (online/offline count) | Quick health overview of entire port |
display ont autofind {port} | ONTs detected but not yet registered | When a new/replaced ONT isn’t showing up |
display ont register-info {f/s/p} {id} | Registration history — all up/down events with timestamps | Diagnosing intermittent or flapping ONTs |
display ont alarm-info {port} {id} | Current active alarms on an ONT | When optical levels seem fine but service is degraded |
display port state {port} | OLT PON port optical module TX power, temperature, SFP status | When all ONTs on one port are affected |
display ont version {f/s/p} {port} {id} | ONT firmware version, vendor ID, equipment ID | Before firmware upgrade decisions |
display ont wan-info {f/s/p} {port} {id} | WAN IP, VLAN, gateway info on the ONT | Service-layer issues after optical is confirmed OK |
display mac-address port {f/s/p} | MAC addresses learned on a port | Verify subscriber traffic is flowing post-fix |
display ont port state {port} {id} eth-port all | LAN port status on the ONT | When fiber is fine but subscriber’s LAN port is down |
The Complete Diagnostic Sequence
Common Issues Found with display ont optical-info — and How to Fix Them
Issue 1: ONT Rx Power Below -27 dBm
Causes: fiber break/cut, dirty or damaged SC connector, degraded splitter port, excessive fiber length, too many splices with high loss, or wrong splitter ratio.
Fix sequence:
- Clean all SC/APC connectors in the path (OLT port, patch panel, splitter ports, ONT port)
- Use an OTDR to locate any reflections or loss events in the fiber
- Check splitter output power with a PON power meter (should match other ports on same splitter ±0.5 dB)
- Reduce splitter ratio if overcrowded (e.g. 1:64 → 1:32 for long-distance runs)
- Check total link budget: OLT TX – path loss – splitter loss = ONT Rx (should be above -27 dBm)
Issue 2: Low ONT Tx Power with High Laser Bias Current
Meaning: The ONT laser is working harder than it should (high current) to produce weak output. This is a classic sign of a laser diode nearing end of life.
Fix: Plan ONT replacement. This is a hardware failure — no software fix or fiber cleaning will resolve it. Schedule replacement before it fails completely and takes the subscriber down unexpectedly.
Issue 3: High ONT Temperature
Causes: ONT installed in an enclosed box with no ventilation, direct sunlight exposure, inadequate air circulation, or faulty ONT cooling.
Fix: Improve ONT housing ventilation, add ventilation holes, relocate ONT away from direct heat, ensure airflow around the device. If the ONT is in an outdoor enclosure in a tropical climate, consider a shaded, ventilated IP54-rated box.
Issue 4: Voltage Out of Range
Meaning: The ONT optical module is receiving insufficient power. This can cause erratic behavior, intermittent offline events, and eventually permanent failure.
Fix: Check the ONT power adapter — test output voltage with a multimeter. Replace the adapter if voltage is low. Also check for corroded power connectors on the ONT itself.
Issue 5: N/A or No Output from Command
Meaning: The ONT is not online. Optical transceiver data is only accessible when the ONT is actively registered and running.
Fix: Run display ont info 0 5 first to check the run state. If it shows offline, troubleshoot the offline issue first using the ONT offline guide.
display ont optical-info reveals, never look directly into a fiber connector or cable end — even on what appears to be an inactive port. Invisible 1310nm/1490nm laser light from GPON systems can cause permanent eye damage. Always use a proper fiber inspection microscope, endface camera, or fiber inspection probe. Wear appropriate safety eyewear when working with fiber.Using display ont optical-info for Proactive Daily Monitoring
The best NOC teams don’t wait for customers to call — they spot deteriorating optical levels before ONTs go offline. Here’s how to build a simple proactive monitoring habit:
Daily NOC Health Check Routine
Setting Optical Alarm Thresholds
Instead of manually checking every day, configure alarm profiles so the OLT alerts you automatically:
Frequently Asked Questions
optical-info is the port-id (the PON port within the current GPON interface, typically 0–7). The second number is the ONT-ID (the specific ONT on that port, 0–127 for GPON). So display ont optical-info 0 1 checks ONT ID 1 on port 0. Use display ont optical-info 0 all to see all ONTs on port 0 in a summary table.Run state: offline), the transceiver cannot be queried remotely. Run display ont info {port} {id} first to confirm the run state. If offline, troubleshoot the registration/offline issue before querying optical info.display ont optical-info 0/1/0 1 where 0/1/0 means slot 0, port 1, sub-port 0. This lets you query any ONT without navigating into the interface context, which is useful for NOC scripts or quickly checking ONTs across multiple ports.Quick Reference Cheat Sheet SAVE THIS
| Task | Command |
|---|---|
| Check single ONT optical info (full detail) | display ont optical-info 0 1 |
| Check ALL ONTs on port (summary) | display ont optical-info 0 all |
| Check from global view (no interface) | display ont optical-info 0/1/0 1 |
| Check ONT run state and last down cause | display ont info 0 1 |
| Check all ONT states on a port | display ont info summary 0 |
| Check ONT alarm history | display ont alarm-info 0 1 |
| Check ONT registration up/down log | display ont register-info 0/1/0 1 |
| Check OLT PON port optical module | display port state 0 |
| Find auto-discovered unregistered ONTs | display ont autofind 0 |
| Check ONT firmware version | display ont version 0/1/0 0 1 |
| Check ONT WAN / service info | display ont wan-info 0/1/0 0 1 |
| Reboot ONT remotely | ont reset 0 1 |
| Check MAC addresses on port | display mac-address port 0/1/0 |
| Check ONT LAN port status | display ont port state 0 1 eth-port all |
Conclusion
The display ont optical-info command is, without exaggeration, one of the most valuable tools in a Huawei GPON engineer’s daily toolkit. In a single command, it tells you whether an ONT’s signal is strong or fading, whether its laser is aging, whether it’s overheating, and whether its power supply is stable — all without leaving the OLT CLI or sending a technician to the field.
The key is knowing how to read the output systematically: check Rx power for downstream fiber quality, check Tx and laser bias current for ONT hardware health, check OLT Rx for upstream path quality, and watch temperature and voltage as early-warning indicators. Use display ont optical-info 0 all daily to spot marginal ONTs before they go offline — that’s the difference between reactive firefighting and proactive network management.
Bookmark this guide, share it with your NOC team, and check the related guides below for the next level of Huawei GPON troubleshooting depth.