[plug] PPC firewall question

[Denis Brown]

At 09:00 9/09/2003 +0800, you wrote:
>On Tue, 9 Sep 2003 08:55 am, James Devenish wrote:
> > In message <1063067784.1031.203.camel at latte.internal.itmaze.com.au>
> >
> > on Tue, Sep 09, 2003 at 08:36:24AM +0800, Onno Benschop wrote:
> > > On Tue, 2003-09-09 at 08:07, Quintin Lette wrote:
> > > > By the way does anyone know how to use the aaui port on a powermac
> > > > under linux, that would make life so easy... 2 onboard nics (10mb RJ45
> > > > + 10mb AAUI) and 3 pci slots on the 7200/x series Powermacs :-)

<snip thoughts on using both ports...>

If it is a standard NIC implementation then there is basically one piece of 
"port hardware" being the chipset with which the drivers interact and two 
"external interfaces" to it, in this case AAUI and RJ45.   Internal to the 
chipset will be a one-bit I/O port (or one bit of a byte / word I/O port) 
that controls which of the two external interfaces communicate with the 
chipset.   This is one of the things you set up in, for example, a 3-Com 
card with the setup software.  In Earlier Times (tm) there were jumper 
links that made a physical selection between the external interfaces.

I suppose that given (a) a 10 Mbit limit and (b) a fast-enough CPU and (c) 
fancy software in the drivers, one could imagine a scenario where the 
driver "sampled" both external interfaces at high speed, high enough to 
resolve signals coming in on each of the interfaces.   However the chances 
of missing bits on one or both interfaces could make this scheme very 
flaky.   Ergo an impractical scheme.

Having said that, and not having a 7200 available to inspect physically, 
Apple just may have dropped in two complete instances of "port hardware" in 
which case the above is rendered false.   Over to the Apple gurus...

Cheers,
Denis