Half/full duplex

[Donald Becker]

On Thu, 1 Apr 1999, Stavros Kassinos wrote:

> How can I make sure that a 3c905 card is running in half-duples mode?  I
> am using it to connect a home LAN server (linux box with 2 NICS) to
> another linux box via a hub and the transfer rates are extremely low. I
> have been told that when used with a hub 3c905 should be in half-duplex
> mode. Is this correct?

Yes, when using a repeater you must be in half duplex mode.
The driver uses half duplex mode by default.

Note: You can confirm the duplex setting using 'vortex-diag', as done below
  http://cesdis.gsfc.nasa.gov/linux/diag/index.html

> And if yes then how can I set it to that? In the
> options listed in http://cesdis.gsfc.nasa.gov/linux/drivers/vortex.html
> I do not see one specifically for half-duplex.

You cannot force half duplex, since that's the default.

> I know the card is
> running in full-duplex because I run the vortex-diag. Also noted some
> checksum errors (?).  Here's the output:

> ./vortex-diag -a -e -m
> vortex-diag.c:v1.07 11/24/98 Donald Becker (becker@cesdis.gsfc.nasa.gov)
> Found a 3Com PCI Ethernet 3c905 rev 0 at 0xff00.
>  Indication enable is 06c6, interrupt enable is 069e.
>  No interrupt sources are pending.
>  Transceiver/media interfaces available:  MII.
>  MAC settings: full-duplex.

Hmmm, check /etc/conf.modules to make certain no options are set!

> Maximum packet size is 0.
>  Station address set to 00:10:4b:9a:ec:4a.
>  Configuration options 4000.
> Parsing the EEPROM of a 3Com Vortex/Boomerang:
>  3Com Node Address 00:10:00:10:00:10 (used as a unique ID only).
>  OEM Station address 00:10:00:10:00:10 (used as the ethernet address).
>  Manufacture date (MM/DD/YY) 0/16/0, division , product .
> Options: none.
>   Vortex format checksum is incorrect (00 vs. 10).
>  Cyclone format checksum is incorrect (00 vs. 10).

Hmmm, I'm not certain why the EEPROM isn't being read correctly.  (Note that
the contents are 0x1000.)

>  MII PHY found at address 24, status 786f.
>  MII PHY 0 at #24 transceiver registers:
>    3100 786f 2000 5c01 0141 40a1 0001 0000

You link partner is reporting 10-HDX and 100-HDX.
The driver shouldn't have switched to FDX automatically.

Donald Becker					  becker@cesdis.gsfc.nasa.gov
USRA-CESDIS, Center of Excellence in Space Data and Information Sciences.
Code 930.5, Goddard Space Flight Center,  Greenbelt, MD.  20771
301-286-0882	     http://cesdis.gsfc.nasa.gov/people/becker/whoiam.html