[vortex] 3c905C: Packet losses, but only with a switch

[Donald Becker]

On Mon, 3 Jul 2000, Giuseppe Ciaccio wrote:

> I recently purchased two 3COM 3c905C adapters, and tested them under
> Linux 2.2.13 with driver 0.99H .  In order to avoid any negotiation-related

Hmmm, the "real" 0.99H predates the 3c905C and thus does not support that
version.  The first version with 3c905C support is 0.99L.  You likely have a
driver version modified to recognize the card, but not really support it.

> problems, I explicitly set up the media type and duplexness using the
> 3c90xcfg.exe config program (under DOS).
>
> Then, I connected the two NICs by an Intel Express 510T switch.
> The switch is manageable, and I explicitly programmed the duplexness of
> each port to match the NIC duplexness.

This is usually bad: autonegotiation is a reliable technology.  If you have
a broken switch, you should default to half duplex rather than forcing full
duplex.


> The result:
> very frequent packet losses using "ping -f", with half-duplex as well as
> full-duplex.
> The problem does not occur if a crossover cable is used in place of the switch.

This is almost certainly a duplex mismatch of some type.
What does 'vortex-diag' report about the duplex?


Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Beowulf Clusters / Linux Installations
Annapolis MD 21403