Date   : Tue, 28 Jul 2009 11:38:20 +0100
From   : robert@... (Rob)
Subject: Econet <> Ethernet

On 28/07/2009, Phil Blundell <pb@...> wrote:
> AUN won't go across the internet on its own because of the way the
> addressing is done (the Econet net and station numbers are mapped
> directly into the low-order octets of the IP address); it also expects
> that all the hosts will be in the same broadcast domain.  To make it
> routable in the general case, you'd need to wrap it in some kind of
> extra encapsulation.  That certainly wouldn't be impossible and I might
> have a go at it when I get back from my holiday.

Yups.. the way I've done it with BeebEm is to continue to support the
Econet,cfg file that was created for the original implementatin of
econet-over-IP.  This basically allows one to specify "override" ip
adress/ports for particular stn.net combinations, if you need to.

At the other end, to cope with receiving packets that come from
non-standard addresses/ports, any incoming packets from an otherwise
unrecognised IP address are just added to the tables based on the
net.stn in the packet..

But you don't need to use that because I also support an AUNMap file
(copied off the A5000) to link net number to IP range, so to contact a
given net.stn, it checks the overrides first, checks map for the
network range, then assumes the last octet based on the station
number.   (It then remembers all this for next time.)

Thus for me, 192.168.0.x is net 128,  192.168.12.x is net 132 and
192,168.13.x is net 133.

With the matching AUNMap in the RISC OS machine, it all seems to work,
although I've only got tested it across two subnets so far.  AUN seems
to rely on IP routing, rather than the bridge econet uses, so it
surprised, and pleased me, that it "just worked" without having to
emulate a bridge as well.

I'm still struggling a little with broadcasts, but I've not had much
time to spend on it recently; it's only going to be something simple
wrong,  Plus, I really need to find something relibale that uses them
to test, lol.

As soon as I get that sorted, I'll be ready to get the code off to
Mike for inclusion in the released version.

Rob