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RAW NIC Troubleshooting Playbook

Use this playbook when RAW mode does not start, does not send, or does not appear in Wireshark.

1. No adapters listed

Likely causes:

  • Npcap is not installed.
  • Npcap service is disabled.
  • The app is not running with enough privileges.
  • Only loopback, VPN, Wi-Fi, or virtual adapters are exposed.

Actions:

dotnet run --project .\src\PtpLabClock.Console -- --list

Then reinstall/update Npcap and run the app as Administrator.

2. Adapter opens but send fails

Likely causes:

  • Driver blocks injection.
  • Adapter is down or disconnected.
  • Selected adapter is virtual/VPN/Wi-Fi.
  • Security software prevents packet injection.

Actions:

  • Prefer wired Ethernet.
  • Disable unused VPN/virtual adapters during the test.
  • Use a controlled lab switch/TAP.
  • Try another USB Ethernet adapter and record the result in docs/raw-nic-compatibility.md.

3. Send succeeds but local capture does not see the packet

This can happen with some drivers. Local self-capture is useful, but external capture is stronger evidence.

Actions:

  • Run Wireshark on the same adapter.
  • If possible, capture on a mirror/TAP/external analyzer.
  • Use this display filter:
eth.type == 0x88f7 or ptp

4. VLAN packet not visible

Actions:

  • Enable VLAN tag in the app or CLI.
  • Confirm VLAN ID and PCP.
  • Use this capture filter:
ether proto 0x88f7 or (vlan and ether proto 0x88f7) or (vlan and vlan and ether proto 0x88f7)

5. Relay/analyzer still does not accept timing

This tool is a simulator and timing-visibility companion, not a certified timing source. Relay acceptance may depend on real grandmaster quality, domain, profile, BMCA behavior, hardware timestamping, sync accuracy, and network architecture.

Use a proper certified PTP grandmaster for final protection or metering validation.

Evidence to capture in an issue

Include:

  • Windows version.
  • Npcap version.
  • Adapter model and driver.
  • Whether the app ran as Administrator.
  • RAW self-test output.
  • Wireshark screenshot or PCAP.
  • VLAN/QinQ configuration.
  • Whether external capture saw the frame.