AUN - Select Release Note
=========================

1. An introduction to AUN

When Acorn originally released the BBC micro, it had the capability to be
networked using Acorn's own networking system, Econet. This was commonly
used to share the then-expensive printers and disc drives (both floppy and
'Winchester' hard drives).

When the Archimedes series was launched, Acorn retained the Econet network
system, and all the Archimedes series machines (bar the A3010) could be
upgraded with a plug-in board. This gave access to the same network
facilities as were present on the BBC Micro.

The Acorn Fileserver protocol was used to allow BBC and Archimdes machines
to access files stored on a fileserver. The user would login with their
username and password, and would be able to use their own area of the
fileserver disc. In a similar way, the Printer Server Protocol allowed a
network user to print to a printer on a remote machine, shared with other
users.

Both Acorn and SJ Research produced a range of file server and printer
server solutions. The most common were the SJ Research MDFS, a stand alone
server box that connected to an Econet network and offered file and print
serving, and the Acorn Level 4 fileserver, which allowed an Archimedes
machine to act as a file server and / or a printer server.

Several other products made use of the networking abilities of both the BBC
and Archimedes. These included telextext page servers, terminal connections,
databases and even games.

As application and data sizes grew, the original Econet system was pushed to
its limits. While it was adaquete for transferring the relatively small
amount of data used by the BBC, as the Archimedes started to use megabytes,
Econet was just too slow.

Newer networking techonolgies allowed data to me moved around much quicker
than on Econet - whereas an Econet network was limited to around 200kbits a
second, an Ethernet could run up to 10 megabits a second - 50 times as fast!

Although ethernet was already available on the Archimedes to talk to TCP/IP
networks, usually with Unix servers, most users still wanted to be able to
run all their existing Econet-based applications. Acorn Universal Networking
was the way this was effected.

The term "AUN" has had many meanings in the past, but what we today call
"AUN" in RISC OS Select is a way to allow these Econet-based applications to
be run over an TCP/IP network (typically Ethernet).


2. What's in AUN?

AUN in RISC OS select consists of a number of ROM modules and supporting
disc files and scripts. These are configured using configuration plugins.

There are two main aspects to what is provided. There is the AUN system
itself - the way that Econet-based applications can run, and there are the
file and print server clients.


3. Econet Station Numbering

An Econet network was made up of a number of stations. Two networks could be
connected by means of a Bridge. Each computer connected was uniquely
identified by two numbers, the first was the station number, which could be
between 1 and 254, the second was the network number, which could be between
1 and 127.


4. Translating that to TCP/IP

AUN uses a TCP/IP network to provide the same facilties as Econet. Because
applications expect to be able to reference a station using the net and
station numbers, these must be "mapped" onto IP addresses. This mapping
defines what IP address ranges are used for an econet network.

To avoid clashes on machines that have both an ethernet and an econet
interface, the network number of an AUN station must be between 128 and 251.

The AUN Map file controls the translation between the network number and IP
address. For example, if your network runs on the private IP range of
192.168.0.x, you may want to map this to AUN network 128. This will mean the
machine with the IP 192.168.0.1 has an AUN address of 128.1.


5. Setting up AUN

The "AUN" plugin, in the the !Configure "Networking" section allows the AUN
system to be setup.

The first option is "Enable AUN" - this control wether or not the AUN system
is activated. If you wish to use any Econet-based network applications over
an ethernet network, you will need to enable this.

The current AUN network map is shown below this. The buttons at the side are
used to edit the values in the AUN map. The "Auto-configure AUN maps for
local interfaces" option provides a quick and easy way of setting up a
simple AUN system. It will automatically map each local ethernet interface
to a AUN network, based on that interface's IP address. Often, this will
give a fully functional AUN system without the need for the AUN Map files.

Finally, the current contents of the AUN Map file can be saved by dragging
the icon to a filer window, or a saved map loaded by dragging it to the box.
This allows a map file to be setup on one computer and quickly installed on
several others.


6. NetFS

Earlier we mentioned the file and printer server clients. The "NetFS" plugin
allows us to use these.

Level 4, or Advanced Level 4, allows an Archimedes or RiscPC to act as a
file server to an AUN network, providing a password controlled storage area
and spooled printer facilities. While these products are not provided by
RISC OS ltd, the clients to provide access to them are.

The file server client provides NetFS and a "Net" icon on the iconbar that
allows connections to be made to servers, the printer server client allows
the connection of "Net" to be selected in !Printers, allowing print jobs to
be sent to printer server machines which share one or more printers.

To enable these clients, the "Use NetFS and NetPrint" option should be
enabled. The file server and print server options allow the default file and
printer servers to be set. The default file server will appear in the logon
box when the "Net" icon is clicked.

The "Use ArthurLib" option allows Archimedes and BBC machines to have
seperate "Library" directories on the fileserver. It's usually left on.
