hi!
> > I'm using libpcap-0.6.2 on a linux 2.2.19 kernel machine. The
> > packet timestamps are sometimes jumping back:
> >
> > 02:51:20.084645 [...]: . ack 2840939448 win 32120 (DF)
> > 02:51:20.084360 [...]: . ack 3279847247 win 17424 (DF)
> > 02:51:20.084993 [...]: . ack 744835904 win 8930 (DF)
> >
> > Is this normal behaviour? I see these jumps for about 2-3% of the packets.
> > clock is synchronized via ntp.
Some more figures (obtained with a quick hack using libpcap-2001.09.25):
2.2.19:
stats: 100000 packets received
0 packets dropped
good: 90222 packets
bad: 9778 packets
max delta: 15850 usec
2.4.1:
stats: 100000 packets received
0 packets dropped
good: 99538 packets
bad: 462 packets
max delta: 471 usec
> Does this happen if NTP is shut down?
Yep.
> If your system clock is
> jittery, NTP could be correcting the clock backwards periodically to
> make up for it, which could cause the weirdness you're seeing...
I doubt this. The config.h generated by configure of ntp-4.0.99g defines
ADJTIME_IS_ACCURATE and HAVE___ADJTIMEX. The ntpd would rather die
than running a clock backwards.
Regards,
Joerg
--
Gaertner Datensysteme 38114 Braunschweig
Joerg Schumacher Hamburger Str. 273a
Tel: 0531-2335555 Fax: 0531-2335556
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