Re: questions on -B, performance, mbufs, and

[Rick Jones <rick.jones2 () hp com>]

On 09/28/2011 03:57 PM, Sanjay Sundaresan wrote:
> What is the meaning of dropped by interface ?
> Dropped by kernel means packets dropped due to lack of memory at the kernel
> in the same way what does interface drop signifies ?

If the numbers for dropped by interface correlate with the packet drops 
being reported by ethtool -S <interface> over the length of time tcpdump 
was running, then it means packets dropped by the NIC.  So, do

ethtool -S <interface> > before
tcpdump <your parameters>
ethtool -S <interface> > after

and then "subtract" before from after and compare that with what tcpdump 
reports for dropped by interface.  99 times out of 10 the stats reported 
by ethtool -S are statistics as measured by the NIC itself.

rick jones
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