Excellent article: Troubleshooting
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Show NIC type:
$ lspci | grep net 03:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01)
Show generic information about NIC (supported modes, current speed/duplex…):
# ethtool eth0
Driver Information and Statistics:
$ ethtool -i eth0
NIC statistics:
$ ethtool -S eth0
NIC buffer overflow diagnostic (see RX-DRP):
$ netstat -i –udp eth0
Operating system kernel network buffers overflow diagnostic. InErrors column shows the number of UDP packets that are dropped when the operating system UDP queue is overflowed:
$ watch -d "cat /proc/net/snmp | grep -w Udp"
Application-level socket buffer overflow diagnostic. RcvbufErrors column shows the number of UDP packets that are dropped when the application socket buffer is overflowed:
$ watch -d "cat /proc/net/snmp | grep -w Udp"