Date   : Fri, 29 Jul 2005 18:28:34 +0100
From   : Rob <robert@...>
Subject: Re: Econet-Ethernet bridge

At 16:14 29/07/2005, Johan Heuseveldt wrote:

>Hi Jules,
>
>On Fri 29 Jul, Jules Richardson wrote:
>
>[snip]
>
> >
> > Does it actually have to do much though? I mean isn't functionality just
> > a case of watching packets on each network interface and if they're not
> > destined for that interface, write them out to the other interface?  I'm
> > surprised much memory's needed to do that.
>
>The nets can have different speeds setup for their clocks.
>
>   1 From hi to lo speed you need you need some queue, possibly
>      still sending;
>   2 From lo to hi speed you need the store the data completely, and
>      after being complete, it can be send
>
>  1 is a bit complicated in comparison with 2, and
>  2 can't use the technique of 1
>
>  perhaps both use the technique or 2, so only one protocol is needed.
>  It does puts both nets on hold for longer periods between the frames
>  in the 4-way handshake, than without bridge.
>
>TBH, I don't how how it is really happening, but because of different
>speeds between the nets, it isn't as simple as you thought! :-)
>Time to invetigate the ROM code.

I imagine it'd also be pretty common for an incoming packet to have to be 
queued simply because the destination network was currently in use (perhaps 
by a 20K *view packet...) and it had to wait for the network to be free again..


Now ... can a 6502 drive that ISA based ethernet chip that was being talked 
about?

Rob.