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TR7Enterprise Application Delivery & Security Platform
What is the difference between interface errors and drops?
Short answer
Both count problematic packets but point to different causes (Linux interface statistics). Errors are the packets counted as corrupt: packets that carry a CRC, frame or length error when received, or that run into a carrier or FIFO problem when sent; they usually point to physical problems such as the cable, the port, the transceiver or a speed/duplex mismatch. Drops, on the other hand, are packets that are intact but are discarded without being processed or sent; they arise from causes such as insufficient resources (buffer, queue) or an unsupported protocol. Packets dropped by Firewall or L4 DDoS rules are not counted in the interface drops counter. In TR7, these counters are shown per second with the RX Errors, TX Errors, RX Drops and TX Drops series in the Network Interface Errors panel on the Dashboard screen of the interface; the device total is in the Total Network Errors panel on the Network tab of the home page. The values are read from the interface counters of the operating system.
Where It Is Used in TR7
| Where | Field / label | What for |
|---|---|---|
| Left Monitor Panel → Interfaces → interface → Dashboard → Errors tab | Network Interface Errors (RX Errors, TX Errors, RX Drops, TX Drops; Errors/sec) | Errors and drops per interface |
| Home → Network tab | Total Network Errors (the same four series) | The total of all interfaces |
| Left Monitor Panel → Interfaces → View Settings | Primary Metric = Network Interface Errors | Sorting the interfaces by their error and drop values |
| The L4 DDoS Live View and Dashboard screens of the route table | Dropped traffic charts (L4 DDoS Live View) | Monitoring the packets dropped by the rules (separately from interface drops) |
| WEB-CLI | sys-cmd netstat (netstat) | Error and dropped packet counters per interface with the -i parameter |
Comparison
| Errors | Drops | |
|---|---|---|
| Packet | Corrupt | Intact but not processed / not sent |
| Possible cause | Cable, port, transceiver, speed/duplex mismatch, MTU mismatch | Buffer or queue filling up, overload, unsupported protocol |
| First place to look | The physical connection and the counters of the switch port on the other side | Traffic volume (packets/s), processor load |
| TR7 series | RX Errors, TX Errors | RX Drops, TX Drops |
Common Misconceptions
- "Packets blocked by the Firewall appear as drops." Packets dropped by Firewall and L4 DDoS rules are not written to the interface counters as drops; they are monitored on the L4 DDoS screens.
- "Every drop means a fault." Drops can be seen during short-lived congestion; a continuous increase is investigated.
- "Errors are fixed by software." Errors are mostly at the physical layer; the cable, the port and the speed/duplex setting of both ends are inspected.
How it is done in the documentation
