netstat -di - Idrop vs. Drop

[Jon Schipp]

On FreeBSD what's the difference between Drop and Idrop in the netstat
output?

$ netstat -di
Name    Mtu Network       Address              Ipkts Ierrs Idrop
Opkts Oerrs  Coll Drop
bge0*  1500 <Link#1>      00:16:d4:e3:49:31        0     0     0
 0     0     0    0
wpi0   2290 <Link#2>      00:1b:77:86:2d:fa        0 53068     0
179587     3     0    0

The man page doesn't explain them.

Also, does netstat get the drop count from the NIC or from a kernel buffer?
For instance, if the NIC can't accept any more packets because of the lack
of descriptors, will the packets lost be reported as one of the drop values
in netstat?

I ask because in Linux, ifconfig reads from /proc/net/dev and as for as I
know, it drops only when the kernel buffer is full. So if the NIC wouldn't
accept packets due to lack of descriptors you wouldn't know about it i.e. it
hasn't made it's way into kernel memory.

that and netstat on FreeBSD has the -B option for the BPF buffer stats, so
right now it makes sense that netstat -di reports the drop count from the
NIC/driver itself.

Right/Wrong?

Any help is appreciated, Thanks
-- 
- Jon
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