[vortex] 3c905C: Packet losses (a more precise description)

[Andrew Morton]

Donald Becker wrote:
> 
> It should always be safe to enable Tx flow control when your link partner
> requests it.

I see.  So a switch which advertises flow control will implicitly _not_
perform multicasting of flow control packets from malicious hosts.

Whereas a switch which does _not_ advertise flow control capability
presumably doesn't know about flow control and will hence multicast the
attacker's packets.

So the logic for enabling flow control on the 3com cards should be

  user_asked_for_it && full_duplex && partner_supports_it.


> Well, I can't be confusing it with the Intel chips.  They have a bug
> where their automatic FC setting based on negotiation fails-on.  It sends
> FC frames even on half duplex links.  The bug manifests itself by hosing
> your network when a Linux machine crashes or shuts down without doing
> 'ifconfig eth0 down'.  "That'll teach you to never shut me down."

How nice.

What's your overall opinion on the 3com cards, Donald?  Compared with
tulip, eepro, etc?