====== NETWORKING TROUBLESHOOTING ======

Excellent article: [[http://ref.onixs.biz/lost-multicast-packets-troubleshooting.html|Troubleshooting]]\\
One more article: [[https://community.mellanox.com/s/article/counters-troubleshooting-for-linux-driver|Mellanox]]

==== GENERIC ====

Show NIC type:
<code bash>
$ lspci | grep net
03:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01)
</code>

Show generic information about NIC (supported modes, current speed/duplex...):
<code bash>
# ethtool eth0
</code>

Driver Information and Statistics:
<code bash>
$ ethtool -i eth0
</code>

NIC statistics:
<code bash>
$ ethtool -S eth0
</code>
==== BUFFER OVERFLOW ====

NIC buffer overflow diagnostic (see RX-DRP):
<code bash>
$ netstat -i –udp eth0
</code>

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:
<code bash>
$ watch -d "cat /proc/net/snmp | grep -w Udp"
</code>

Application-level socket buffer overflow diagnostic. RcvbufErrors column shows the number of UDP packets that are dropped when the application socket buffer is overflowed:
<code bash>
$ watch -d "cat /proc/net/snmp | grep -w Udp"
</code>