ifconfig shows dropped rx packets
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After updating to SLES 11 SP2 packets are being dropped
Dropped counter incrementing
rx_dropped counter is incrementing
Customers have reported seeing dropped packets when examining statistics on their network card, bonds, or virtual interfaces.
Softnet backlog full
Bad / Unintended VLAN tags
Unknown / Unregistered protocols
IPv6 frames when the server is not configured for IPv6
If any frames meet those conditions, they are dropped before the protocol stack and the rx_dropped counter is incremented.
host:~# ifconfig <interface> promisc
And then watching the rx_dropped counter. If it stops incrementing while the NIC is in promiscuous mode; then it is more than likely showing drops because of the reasons listed earlier. If frames continue to be shown as dropped, investigation should take place to determine root cause.
Many administrators find it useful to perform performance testing on their interfaces to see if the alleged drops are hurting actual performance. Using a tool like iperf can help determine if your interfaces are performing near to their advertised speed.
This effect is seen starting from SLES 11 SP2, as it utilizes a 3.x kernel series. Previous SLES versions do not exhibit it (that are using kernels prior to 2.6.37)
Additional information can be found by researching commit # caf586e5
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- Document ID:7007165
- Creation Date:17-MAY-12
- Modified Date:17-SEP-14
- SUSESUSE Linux Enterprise Server
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