Tulips works but my brain does'nt

Thu Jan 6 01:48:04 2000

Chris wrote:

> G'day to everyone
> We have recently upgraded our office network of
> Linux and Win 9x/NT boxes to 100baseTX. The new
> ethernet cards are CNet PRO 120's they have a
> Macronix MX98715 / MX98725 (rev 32) chipset.
> Our Linux boxes currently run Mandrake Linux 6.1 with
> a 2.2.13 kernel. The shipped tulip module had problems
> when ifconfig was run, but tulip v.0.91 works fine without
> modification. I am using the options=11 in conf.modules.
> Everything is going OK but now and then our server
> disappears without complaining or logging anything.
> If I disconnect it from the hub and plug it back in
> everything is back to normal. I don't think its being
> partitioned ??
> I am a little unsure of the duplex that it should be set  to.
> tulip-diag.c:v1.19 10/2/99 Donald Becker (becker@cesdis.gsfc.nasa.gov)
> Index #1: Found a Macronix 98715 PMAC adapter at 0xe800.
>  Port selection is 10mpbs-serial 100baseTx scrambler, full-duplex.
>  Transmit started, Receive started, full-duplex.
>   The Rx process state is 'Waiting for packets'.
>   The Tx process state is 'Idle'.
>   The transmit threshold is 128.
> Since I'm a linux user, I have a tendancy to blame the windows machines
> on our network for this sort of thing. Its a good place to start most of
> the
> time !
> Any ideas or comments would be very helpful.
> Thanks
> Chris

Is it a hub or a switch?

Some general guidelines on if its FD or HD:

1- Connecting to hubs should be half duplex  (most 10/100 hubs are actually
hubs in one where each port autosenses and places the connection into the
"correct" hub. The internal hubs are bridged by an internal switch)

2- Connecting to switches can be full duplex if the switch supports it. Some
older ones have to be explicitly told to go to full duplex mode via dip
switches or management software. Sometimes autosensing does not always work

3- Connecting two devices via a crossover cable can be full duplex if both
devices support full duplex, but autosense may fail since it depends on
certain timing signals, so forcing full duplex may be needed in that

Forcing full duplex in some situations where it should be half duplex may
seem to work for a short while, but will eventually fail with symptoms like
what you describe to in some extreme cases total network cascade failure...
{rare, but it happens with some badly designed devices/networks}

Sami Yousif
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http://www.alug.org/     Amarillo Linux Users Group

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