netdata/health/guides/net/outbound_packets_dropped.md

Understand the alert

This alert tracks the number of dropped outbound packets on a specific network interface (${label:device}) within the last 10 minutes. If you receive this alert, it means that your system has experienced dropped outbound packets in the monitored network interface, which might indicate network congestion or other issues affecting network performance.

What are dropped packets?

Dropped packets refer to network packets that are discarded or lost within a computer network during transmission. In general, this can be caused by various factors, such as network congestion, faulty hardware, misconfigured devices, or packet errors.

Troubleshoot the alert

1. Identify the affected network interface:

Check the alert message for the ${label:device} placeholder. It indicates the network interface experiencing the dropped outbound packets.

1. Verify network congestion or excessive traffic:

Excessive traffic or network congestion can lead to dropped packets. To check network traffic, use the nload tool. If it isn't installed, you can follow the instructions given here.

nload ${label:device}

This will display the current network bandwidth usage on the specified interface. Look for unusually high or fluctuating usage patterns, which could indicate congestion or excessive traffic.

1. Verify hardware issues:

Check the network interface and related hardware components (such as the network card, cables, and switches) for visible damage, loose connections, or other issues. Replace any defective components as needed.

1. Check network interface configuration:

Review your network interface configuration to ensure that it is correctly set up. To do this, you can use the ip or ifconfig command. For example:

ip addr show ${label:device}

or

ifconfig ${label:device}

Verify that the IP address, subnet mask, and other network settings match your network configuration.

1. Check system logs for networking errors:

Review your system logs to identify any networking error messages that might provide more information on the cause of the dropped packets.

grep -i "error" /var/log/syslog | grep "${label:device}"

1. Monitor your network for packet errors using tools like tcpdump or wireshark.

Useful resources

1. How to monitor network bandwidth and traffic in Linux