Identifying a network bottleneck / packet loss on CentOS

We can check for for packet loss at the hardware level using ethtool:

ethtool -S eth0

Typically (although can vary) you are looking for a counter such as:

rx_*_errors

When the packets are received from the NIC they are then placed into send and receive queues - we should ensure that none of them are currently full - we can view these with:

ss -nmp

and finally check for protocol errors with netstat:

netstat -s

Sources

https://access.redhat.com/sites/default/files/attachments/20150325_network_performance_tuning.pdf