All faultfinding roadmaps · FF-01 · Deployed / workshop / training
No service, an intermittent fault, or an unclear starting point.
Have to hand
Site / network diagram, commissioning record, access to status indicators and an incident log.
Before you start
Record the current state before a restart. Confirm the affected service, permitted work and a way to retain or recover management access.
Follow the equipment manual and local procedure. If a tool, permission, safe test setup or required measurement is unavailable, record the result as unknown and escalate with the available evidence. Change one item at a time.
For offline use, print or save this page as a PDF using your browser’s Print command. Include any linked roadmaps you expect to need.
Checks on this page
- 1. Define the symptom and the working boundary
- 2. Check power and the physical connection
- 3. Choose the next diagnostic path
- V. Verify recovery
- E. Escalate
1. Define the symptom and the working boundary
- Record UTC time, affected equipment, the exact failing operation and when it last worked. Note recent changes, weather and whether one or several users are affected.
- Follow the intended chain: user device → local interface → switch / radio → network path → destination service. Identify the last point known to work; do not assume a shared symptom proves a common cause.
Can the checks be performed within the agreed access and outage conditions?
- Yes
Start with device power and the local connection.
Next: FF-01 · Check 2: Check power and the physical connection.
- No / uncertain
Collect available status remotely. Record the access or outage constraint and request the appropriate support.
Next: E · Escalate with evidence.
2. Check power and the physical connection
- Check device / peer power, alarms, Ethernet carrier, external connectors and obvious cable damage. For PoE, check the specified injector / switch mode, budget and cabling. A power light alone does not prove healthy operation.
- Do not open energised equipment or disconnect an active RF feed. For an approved substitution, use a compatible known-good supply, cable or port and change one item at a time.
Is there an obvious power or connection fault?
- Yes
Correct the identified issue within the equipment procedure; otherwise record it for repair. If corrected, repeat the original failing operation.
Next: V · Verify recovery.
- No
Use service scope and radio evidence to choose the next layer.
3. Choose the next diagnostic path
- Review both ends of a radio link where possible. Compare current signal / quality and alarms with the commissioning baseline.
- More than one fault may be present. Follow the strongest evidence, record each finding, then repeat the original service test.
Which observation best matches the fault?
- IP / application failure; no clear RF alarm
Check interface, addressing, route, name resolution and service.
Next: FF-02 · Check 1: Does the local interface have a usable link?.
For packet-level follow-up on an authorised network, use Wireshark in Practice.
- Weak, noisy or unstable radio link
Compare received signal, noise and error trends at both ends.
- VSWR / reflected-power alarm
Check the feed-system match using the specified test procedure.
- Damaged cable / connector or unexplained loss
Inspect and isolate the cable assembly.
Next: FF-06 · Check 1: Inspect connections and identify the cable type.
V. Prove the service is restored
- Restore the approved configuration, connections, covers and weather seals. Remove test equipment and temporary changes using the equipment procedure.
- Repeat the original failing user operation and the relevant measurements. Check both ends where applicable; ping success or a good RF reading alone is insufficient.
- Compare before / after readings with the equipment limits, required service level and baseline under representative traffic.
- Observe for the agreed period, record remaining limits and return the equipment to the responsible operator. A brief pass does not establish long-term availability.
Meets the agreed requirements: record the evidence and corrective action in the fault record. Close the fault through the normal reporting process.
Fails / no correction / still uncertain: keep the fault open. Record the last confirmed working boundary and remaining symptoms; avoid repeating unchanged checks. Escalate with evidence.
E. Escalate with evidence
Send the record through the approved support channel. Exclude credentials, tokens and unnecessary sensitive details.
- System / location, UTC time, impact, exact failing operation, last working state and recent changes.
- Roadmap code and check reached, expected result, actual readings, instrument / command used, units and measurement reference point.
- Relevant interface counters, addressing / route, neighbour state, bounded path tests, resolver results and service logs.
- For RF: measurements at both ends, band / bandwidth / mode, baseline, cable type / length, calibration settings, traces and installation observations.
- Changes and substitutions tried, their results, current configuration, working boundary, missing tools / access and the next support action needed.
Fault record
Use your incident log, or print this space for field notes. This page does not store incident details.
UTC date / time and operator
System / location and incident reference
Symptom and last working state
Check reached and expected result
Before / after readings, units and test setup
Change / substitution and result
Verification operation and observation period
Open / resolved, handover owner and next action
Technical references
The decision sequence combines the references below. Product examples explain the method; use the manual for your deployed equipment to set acceptance limits.
- Linux kernel — network interface operational states
- ethtool — Ethernet settings and statistics
- Cisco — interpreting reported noise and SNR
- Anritsu — understanding cable and antenna analysis (PDF)
- Keysight — instrument input protection (PDF)
Reference content: revision 1, 15 September 2026. Generic source-reviewed guidance; use site and equipment-specific procedures for actual work.