netstat -s output shows high number of Udp: packet receive errors
Getting high number of UDP packet drops or loss
SNMP trap issue :- SNMP trap seems to be fluctuating on my RHEL server.
Udp: packet receive errors is increased for the following reasons:
Not enough socket buffer space
UDP checksum failure
UDP length mismatch
IPSec Security Policy failure
Run the command netstat -nsu and see the Udp: section:
netstat -su Udp: 559933412 packets received 71 packets to unknown port received. 33861296 packet receive errors <---- HERE 7516291 packets sent Socket buffer checking:
The current system-wide default socket buffer size can be determined with the commands:
sysctl net.core.rmem_max sysctl net.core.rmem_default
This can be confirmed by watching socket statistics whilst packet receive errors is growing by running ss -nump at regular intervals, for example:
while true; do ss -nump; sleep 1; done
This will produce output as follows:
State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 0 192.168.0.2:4500 192.168.0.1:4500 users:(("processname",pid=1234,fd=3)) skmem:(r0,rb212992,t0,tb212992,f4096,w0,o0,bl0)
If the Recv-Q statistic is regularly growing large, such as approading the system-wide rmem_max, then increase the socket buffer size.
Note this means the application is not receiving from the buffer fast enough. It may be necessary to reconfigure or redesign the application to perform better.
The statistic Udp: packet receive errors is reporting the SNMP MIB called UDP_MIB_INERRORS.
run udp server
nc -4 -u -l 2389
cli to server
echo -n "hello" | nc -u x.x.x.x 2389