Understanding RTNICDiag: A Beginner’s GuideRTNICDiag is a command-line diagnostic utility often used to inspect and troubleshoot real-time network interface controllers (NICs) and related drivers. For systems administrators, network engineers, and developers working with high-performance or embedded networking, RTNICDiag provides a focused set of tools to gather status, health, and performance data from NICs, firmware, and associated subsystems. This guide explains what RTNICDiag does, how to use it, common commands and outputs, troubleshooting steps, and practical examples to help beginners get started.
What RTNICDiag is and why it matters
RTNICDiag is designed to expose low-level information about network interface hardware and drivers that typical high-level tools (like ping, ifconfig/ip, or netstat) don’t show. It can reveal firmware versions, link-level statistics, hardware error counters, queue and interrupt configuration, and diagnostic logs. This deeper visibility helps identify performance bottlenecks, hardware faults, misconfigurations, and driver/firmware mismatches that can cause packet loss, latency spikes, or complete interface failure.
Typical use cases:
- Diagnosing intermittent packet drops or CRC errors.
- Verifying firmware and driver compatibility after updates.
- Analyzing queue and interrupt balance for high-throughput servers.
- Collecting information for support tickets when escalating to hardware vendors.
How RTNICDiag works (high-level)
RTNICDiag interacts directly with device drivers and sometimes with NIC firmware to request diagnostic data. Depending on the platform and NIC vendor, RTNICDiag may use ioctl calls, vendor-specific kernel modules, or a dedicated userspace utility that communicates via sysfs, netlink, or device files. The output format varies by vendor but usually includes structured sections for device info, link statistics, error counters, queue states, and logs.
Installing and invoking RTNICDiag
Installation and availability depend on your operating system and NIC vendor. On many systems RTNICDiag is included with vendor support packages or as part of a diagnostic toolkit.
Basic invocation pattern (examples — actual command names/options vary by vendor and platform):
- rtnicdiag –list
- rtnicdiag –interface eth0 –status
- rtnicdiag –collect –output /tmp/rtnic_report.txt
Run with elevated privileges (root or sudo) because RTNICDiag often needs direct access to device interfaces and kernel facilities.
Common RTNICDiag sections and what they mean
Below are typical sections you’ll encounter and how to interpret them.
Device identification
- Manufacturer and model
- PCI/PCIe IDs and bus location
- Firmware and driver versions
Why it matters: mismatched firmware/driver often causes subtle bugs.
Link and PHY status
- Link speed (e.g., 1GbE, 10GbE, 25GbE)
- Duplex and auto-negotiation state
- PHY temperature and alarm thresholds
Why it matters: link negotiation failures or thermal issues can cause drops or resets.
Error counters
- CRC errors, frame alignment errors, FCS failures
- Dropped packets due to buffer overflow
- Link resets and reinitializations
Why it matters: trending these counters helps distinguish between transient congestion and hardware faults.
Queue and interrupt configuration
- Number of TX/RX queues
- IRQ mapping and CPU affinity
- Flow steering or RSS (receive-side scaling) configuration
Why it matters: poor queue/IRQ distribution leads to CPU bottlenecks and uneven packet handling.
Statistics and performance
- Packets/sec, bytes/sec per queue
- Latency metrics (if supported)
- Offload feature status (checksum offload, TSO/GSO, LRO)
Why it matters: verifies that offloads are enabled and functioning to reduce CPU load.
Logs and event history
- Firmware or driver-reported events
- Link up/down timestamps
- Diagnostic self-test results
Why it matters: provides historical context for when faults began.
Example RTNICDiag session (generic)
Below is a condensed example of the kind of output you might see and how to read it.
- Run: sudo rtnicdiag –interface eth0 –status
- Example output excerpts:
- Device: Acme NIC X1000, PCIe 0000:af:00.0
- Firmware: v2.3.4, Driver: rte_nic_driver 1.2.0
- Link: 25Gbps, Full duplex, Auto-negotiation: OK
- RX errors: CRC=12, Drops=43, Alignment=0
- TX errors: Retransmits=0
- RX queues: 8, IRQs: 8, RSS: enabled (hash: toeplitz)
Interpretation: CRC and drop counts are non-zero — investigate cabling, SFP module health, or remote peer. If counts steadily increase under light load, consider hardware diagnostics or firmware rollback.
Troubleshooting workflow using RTNICDiag
- Reproduce the issue (if safe): document load, packet rates, and time of occurrence.
- Capture baseline: run RTNICDiag when system is healthy to have comparison data.
- Collect current diagnostics: device info, counters, logs, queue stats.
- Correlate with other tools: tcpdump/wireshark, ethtool, dmesg, system logs, perf/top.
- Isolate variables: change cable/SFP, move NIC to different PCIe slot, test with another host.
- Apply mitigations: enable/disable offloads, adjust interrupt affinity, increase buffer sizes.
- If unresolved, gather a full report (device IDs, firmware, driver, counts, logs) and open vendor support ticket.
Practical tips and gotchas
- Always run diagnostic commands with root privileges; otherwise some data will be inaccessible.
- Keep firmware and driver versions documented — many issues stem from incompatible versions.
- When counters are large, capture timestamps to compute rates (errors/sec), not just raw totals.
- Remember environmental factors: temperature, power supply instability, and bad optics can mimic software faults.
- Offload features can hide packet-level issues; temporarily disabling offloads (checksum/TSO/LRO) can help reveal true packet behavior for debugging.
- Use careful testing when changing IRQ affinity or queue counts on production systems; improper settings can reduce throughput or increase latency.
Example troubleshooting scenarios
Scenario A — Increasing RX CRC errors:
- Check SFP/module compatibility and cleanliness of optical connectors.
- Replace the cable/module to rule out physical layer.
- Verify firmware revision; check vendor release notes for known PHY issues.
Scenario B — High CPU usage on one core with high networking load:
- Inspect IRQ/queue affinity; enable RSS and distribute queues across CPUs.
- Check whether offloads are active; if not, enable checksum offload/TSO.
- Confirm driver supports multiple queues and is configured accordingly.
Scenario C — Intermittent link drops:
- Review event logs for link transition timestamps.
- Check auto-negotiation settings and forced speed/duplex mismatches.
- Monitor temperature and power; investigate SFP thermal warnings.
When to escalate to vendor support
Collect these before contacting support:
- Full RTNICDiag output (device, firmware, driver).
- dmesg and system logs covering the timeframe of the issue.
- tcptrace/tcpdump samples or flows demonstrating the problem.
- Steps already taken (cable swap, firmware rollback, etc.) and their results.
Vendors often require firmware/driver pairings and logs; providing a complete diagnostic dump speeds resolution.
Summary
RTNICDiag is a specialized tool that surfaces low-level NIC and driver data beyond ordinary network utilities. Used methodically, it helps diagnose physical, firmware, and configuration problems affecting network performance and reliability. Beginners should focus on learning common sections of the output, capturing baselines, and correlating RTNICDiag findings with other system logs and packet captures.
If you want, I can:
- Provide a sample checklist for gathering diagnostics before contacting support.
- Convert the example usage to commands for a specific NIC/vendor if you tell me the vendor and OS.
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