n drops

Packet drops & CRC framing errors

Usage — n drops

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  Netscrew ("n") — drops (dr, errors, rx-errors) — NIC dropped-packet & error audit (with live 'rising?' check)
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USAGE:
  n dr .                               per-interface drop/error counters on this machine

Target: . = this machine · <host> = remote
Deeper: n dr -h = the concept/theory behind this command

The concept behind it — n drops -h

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  NETSCREW GUIDE: Network Interface Errors & Packet Drops ("n drops")
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WHAT THIS AUDITS:
  Reads the drop and error counters for every network adapter (eth0, enp3s0, docker0,
  br-xxx, veth, Wi-Fi...) twice, 2 seconds apart. Counters are cumulative since boot, so
  the second sample tells old history (steady) apart from a live problem (RISING).
  • Linux:   /sys/class/net/*/statistics (drops, errors, CRC errors)
  • Windows: Get-NetAdapterStatistics (discarded packets & packet errors)
  • macOS:   netstat -i -d (input/output errors & output drops)

TROUBLESHOOTING CHEAT SHEET:
  • RX/TX Drops > 0: Ring buffer exhaustion. Kernel cannot process packets fast
    enough. Increase rx/tx ring size with ethtool -G <iface> rx 4096.
  • CRC / Frame Errors > 0: Physical Layer 1 hardware defect! Bad or bent RJ-45
    Ethernet patch cable, loose SFP+ transceiver, or dirty optical fiber.
  • Carrier Flaps > 0: Faulty switch port, power supply noise, or failing NIC.