Re: 3Com Corporation 3c905C-TX/TX-M [Tornado] initializes in promisc mode

On Mon, 29 Sep 2003, Tobias Poppe wrote:

> It seems as if the chip of the 3Com Corporation 3c905C-TX/TX-M
> [Tornado] (driver 3x59x.o) by default initializes with promisch mode.
> (The chip itself. The PROMISC flag is not shown in the ifconfig <dev>
> output). 
> 
> I send arp-request packets with a destination mac of ff:ff:ff:ff:ff:fe

Uhmmm, that's a multicast address.  Most of the 3Com chips either do not
have a hardware multicast filter, or have one that is unusable.  So the
driver puts the chips into Rx-all-multicast mode, or only adds (never
deletes) multicast filter channels.

Try the same test with a non-multicast address.

An easy way to run this test is with the ether-wake program.
   ftp://ftp.scyld.com/pub/diag/
It will send to arbitrary destination addresses, including multicast
addresses.  I use this program in the driver validation scripts rather
than maintain a unique program to generate packets.


-- 
Donald Becker				[email protected]
Scyld Computing Corporation		http://www.scyld.com
914 Bay Ridge Road, Suite 220		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993

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