Layer 2 Multicasting problem on shut down system brings down all eepro100's on the net!!

[Donald Becker]

On Fri, 10 Sep 1999, Manfred Young wrote:

> The packets with Ether type 8808 frame are 802.3x link flow control packets.
> These packets are meant to be used only when the link is in full duplex
> mode.
> 
> Unfortunately, the eepro100 driver always enables flow control. Since it's
> not always possible to determine the duplex setting for a link, I believe
> that the eepro100 driver should, by default, disable flow control. A new
> option to enable flow control would then be required.

The chip is documented to generate flow control packets only when it is in
full duplex mode.  The driver, by default, sets the chip chip to use the
negotiated duplex.

Since there have been reports that the chip generates Flow Control frames
even in half duplex mode, the documentation must be wrong.  So I changed the
driver to only enable FC when it's explicitly negotiated on a full duplex
link.

The current driver version, v1.09m, includes this change.
  http://cesdis.gsfc.nasa.gov/linux/drivers/kern-2.3/eepro100.c
  ftp://cesdis.gsfc.nasa.gov/pub/linux/drivers/kern-2.3/eepro100.c

> > On occasion, after a linux box is halted (we've reproduced it on a Red
> > Hat 6.0 system running with the stock kernel 2.2.5-15(?)) but the power
> > remains on, the eepro100 card will start multicasting to mac
> > destination: 01:80:c2:00:00:01 an Ether type 8808 frame. This, in turn,
> > causes ALL other eepro100's on the network to pause transmitting,
> > effectively, crippling all network communications to/from ANY machine
> > with an eepro100 card on the network!!

There might be a problem in the RH6.0 system -- the interface is supposed
to be stopped by the shutdown scripts.  Shutting down the interface should
stop the EEPro100 completely.

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