On 16/01/2023 11.25, [EXT] Mohammad Reza Keshavarzianpoor wrote:
yes I tried tcp dump and it says ubuntu is dropping packets 618916 packets captured 1242894 packets received by filter 623578 packets dropped by kernel
"Packets dropped by kernel" means that some aspect of the system isn't keeping up with the network traffic. That could be tcpdump itself (see `-n` and `-B` options), or it could be the network hardware or driver, or the CPU or some other component could be maxed out (perhaps the disk that tcpdump is writing to isn't keeping up).
If you can't eliminate packet drops after making sure that it's not tcpdump itself that is the bottleneck, perhaps look into what tunables your network hardware supports (see ethtool), especially regarding RX queues.
Cheers