promiscuous mode, was Re: [HECnet] Multinet Tunnel Connections to SG1::

[Paul_Koning at Dell.com]

On Jun 8, 2012, at 3:18 PM, Johnny Billquist wrote:

On 2012-06-08 19:02, Paul_Koning at Dell.com wrote:
...
Thanks for making me re-read the DELQA manual again. :-)

You're very welcome!

I'm not totally clear on this point. This might be getting a little too technical and offtopic here, but basically, reading the manual, it might appear that having several unicast addresses in the setup might only be respected if you are running your DELQA in DEQNA mode, and the manual warn against potential performance issues if you do this.
But I had forgotten quite a lot of the DEQNA/DELQA anyway, including that you were supposed to fill the table with your own address to make it full. Gah! I've never liked the Q-bus ethernet controllers. And they are so buggy...

	Johnny

QNA, yes -- it was abandoned after revision L still didn't work right.   LQA is a completely new design that does work, but it is compatible at the driver level with QNA (or nearly so).

The address match is really very simple.   There are no bugs here... the hardware has a 16 entry table and it accepts packets whenever the DA matches any of the 16 entries (essentially a 16 entry CAM).   There are no "valid" bits (as you might find in some more advanced CAMs) so it treats all 16 entries as meaningful addresses.   That means you have to fill in all 16.   

If you don't need 16 distinct values, you simply pad the table with extra copies of any of the meaningful values; that way the result is what you want.   The easiest way to do that is to make extra copies of the entry that specifies the MAC address, but that isn't necessary, it is mentioned only because it's easy to remember.   

	paul