Re: bifurcated results from netperf

Gregory P. Smith (
Fri, 16 Apr 1999 10:59:44 -0700

If you force -either end- of a 100baseT connection to full duplex you
MUST force the other end as well. Auto negotiation -only- works when
both ends are auto negotiating or one end is set to half duplex.
(because auto-negotiation falls back to the lowest common denominator
of half duplex if it couldn't negotiate).


> A few weeks ago I investigated a similar situation. Sometimes I got 96Mbs
> and sometimes as low as 1Mbs.
> My problem was Half vs Full duplex (or shall I say Full vs Auto NIC
> settings). The switch was (sometimes) changing to half duplex when the NIC
> was set to Full. When the NIC was set to AUTO, I always stayed at Full and
> the flaky performance problem never occurred.