Diagnosing packet loss

J65nko j65nko at gmail.com
Tue Nov 22 22:03:01 UTC 2011

On Tue, Nov 22, 2011 at 9:33 PM, Kees Jan Koster <kjkoster at gmail.com> wrote:
> Dear All,
> I am stuck with a machine that shows serious packet loss (about 1% of all traffic is dropped). I tried the obvious (new network cable, different switch port, different ethernet interface on the machine), but the problems remain.
> Another machine that sits in the same rack and is hooked up to the same switch shows no such packet loss issues. The problematic machine is a dual Opteron with FreeBSD 8.2-STABLE from Thu Aug 11 14:05:47 CEST 2011.
> The machine is lightly loaded. A MySQL slave is running, but the machine is not serving queries. Plus a Munin server process.
> I am at a loss where to start diagnosing this. Can you advise me where to look? Are there network buffers that may be overflowing?
> --

To check input/output errors and collisions : netstat -in

Detailed TCP/IP statistics: netstat -s  or  netstat -ss

Checking Receive and Send Queue : netstat -an -f inet

Buffers: netstat -m


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