| 1 | ### Understand the alert |
| 2 | |
| 3 | This alert is triggered when the number of inbound dropped packets for a network interface exceeds a specified threshold during the last 10 minutes. A dropped packet means that the network device could not process the packet, hence it was discarded. |
| 4 | |
| 5 | ### What are the common causes of dropped packets? |
| 6 | |
| 7 | 1. Network Congestion: When the network traffic is too high, the buffer may overflow before the device can process the packets, causing some packets to be dropped. |
| 8 | 2. Link Layer Errors: Packets can be dropped due to errors in the link layer causing frames to be corrupted. |
| 9 | 3. Insufficient Resources: The network interface may fail to process incoming packets due to a lack of memory or CPU resources. |
| 10 | |
| 11 | ### Troubleshoot the alert |
| 12 | |
| 13 | 1. Check the overall system resources |
| 14 | |
| 15 | Run the `vmstat` command to get a report about your system statistics. |
| 16 | |
| 17 | ``` |
| 18 | vmstat 1 |
| 19 | ``` |
| 20 | |
| 21 | Check if the CPU or memory usage is high. If either is near full utilization, consider upgrading system resources or managing the load more efficiently. |
| 22 | |
| 23 | 2. Check network interface statistics |
| 24 | |
| 25 | Run the `ifconfig` command to get more information on the network interface. |
| 26 | |
| 27 | ``` |
| 28 | ifconfig <INTERFACE> |
| 29 | ``` |
| 30 | |
| 31 | Look for the `RX dropped` field to confirm the number of dropped packets. |
| 32 | |
| 33 | 3. Monitor network traffic |
| 34 | |
| 35 | Use `iftop` or `nload` to monitor the network traffic in real time. If you don't have these tools, install them: |
| 36 | |
| 37 | ``` |
| 38 | sudo apt install iftop nload |
| 39 | ``` |
| 40 | |
| 41 | ``` |
| 42 | iftop -i <INTERFACE> |
| 43 | nload <INTERFACE> |
| 44 | ``` |
| 45 | |
| 46 | Identify if there is unusually high traffic on the network interface. |
| 47 | |
| 48 | 4. Check logs for any related errors |
| 49 | |
| 50 | Check the system logs for any errors related to the network interface or driver: |
| 51 | |
| 52 | ``` |
| 53 | sudo dmesg | grep -i "eth0" |
| 54 | sudo journalctl -u networking.service |
| 55 | ``` |
| 56 | |
| 57 | If you find any errors, you can research the specific problem and apply the necessary fixes. |
| 58 |