Date   : Tue, 18 Aug 2009 14:42:14 +0100
From   : philb@... (Phil Blundell)
Subject: maximum econet packet size

On Tue, 2009-08-18 at 14:16 +0100, Rob wrote:
> On 18/08/2009, Phil Blundell <philb@...> wrote:
> > Yeah, that's kind of what I suspected.  I wonder how that sort of stuff
> > was meant to work across the bridge, then.  Guess I'll have to look at
> > the disassembly again and try to figure out what buffer sizes it
> > actually uses.
> >
> > What fileserver were you loading from in that hibasic case?  I'm a bit
> > surprised that any of them would want to send more than 16k in a single
> > packet.
> 
> That was just from Acorn L4.
> 
> I'm not saying it's defiintly sending it as a single packet, but it
> certainly didn't work until I increased the buffer sizes ...

It does sound like it was sending it as a single packet.  There's
probably no reason that wouldn't work with the Beeb since it moves data
directly from the rx fifo to the destination in RAM, there's no
intermediate buffer.  I was just a bit surprised that the fileserver
would choose to use a packet that large, but I guess L4 has no shortage
of buffer space so it isn't too implausible in that case.

I wonder if L4 is smart enough to look at the destination network number
and use larger packets if it knows that the target station is not on the
other side of a bridge.  That'd make some kind of sense; I'll have to
break out my copy of L4 and try it out.

p.