The start of EUnet
------------------
A presentation of "UNIX and networking" on the EUUG conference in Paris
in 1982 started the "European UNIX systems Network", called EUnet.
Soon thereafter links were set up between 10 sites in three countries.

By then only public phone lines were available as carrier; in most
countries autodialers weren't yet allowed and thus not obtainable, so
we simply smuggled a couple of dialers to them to set up the network...
The transport software used was a rather well debugged version of AT&T's
UUCP software package.

Some lessons were taken from the experience that UNIX sites in the United
States had with the UNIX network (then called USENET), leading to rules
for the setup and use of EUnet in Europe.

EUnet is NOT free to join. Responsible for Eunet is:
a. the European UNIX systems Users Group;
b. the CWI in Amsterdam ("mcvax") as the central network node.

The maintenance of the network is centralised in every country
by means of backbone sites, and coordinated by one central site (CWI
in Amsterdam) and network manager.

From 10 sites in the summer of 1982, EUnet has grown to about 500
sites in 1985 with links to Australia, Canada, Israel, Japan and the USA.
A "site" here is defined as a computer in a institute,
directly or indirectly connected to EUnet. This number comprises only
the officially known sites; quite a lot of small local machines connected
up to a EUnet site are not known to the outside world; it is estimated
that currently a total of some 800 sites sowehow are connected to EUnet.


Structure
---------
In every country in Europe (Austria, Belgium, Denmark, Finland, France,
Germany, Greece, Ireland, Italy, Netherlands, Norway, Sweden, Switzerland,
United Kingdom and Yugoslavia) there is - or will soon be established - a
backbone site, responsible for its national sites.
These backbone sites look after the software (screening, maintenance,
and local development), hardware (PTT connections, maintenance) and
administration (accounting, address contacts, routing info exchange, etc).

Most connections inside a country are based on public phone lines, X.25
and private lines.

The inter-backbone links now run over the public X.25 networks, as do most
of the intercontinental links. A few links still have use the phone.
Every backbone site is able to connect directly to another backbone site
(N by N connections).


Software
--------
The basic carrier is AT&T's software called UUCP, running on UNIX machines.
For source license holders of UNIX there is a very reliable UUCP version,
maintained by the CWI. Most distributors of UNIX machines have taken over
this UUCP sofware package.
The package has enhancements like: faster protocols for X.25 usage,
support of PADs, accounting, grading, and better noisy line handling.

Above this transport layer, many user support utilities are made available:
  Electronic mail systems:
    Berkeley Mail system, MH.5 Rand Mail system, UNIX mail system.
  Mail addressing systems:
    Sendmail (for support of ARPA and UNIX address styles, complete with
    usable configuration files and European timezone handling), MMDF.
  News systems:
    electronic news (USENET news 2.10.3) (with compression).
  Routing system:
    an automatic router for path optimization, address and route mapping,
    rerouting and automatic site/route maintenance.
  Accounting system:
    for automatic cost accounting of the network.
The user utility software is free (in C source code) to EUUG members.

Due to the initial start with UNIX systems most of the machines connected
to EUnet are UNIX machines.
However some companies have software available which emulate the
transport UUCP layer, fi. VAX/VMS (UUCP for VMS, UNIX emulations,
or UNIX machines are connected to LANs with non-UNIX machines on the LAN.
By the usage of a UNIX machine as a gateway machine, many users on
non-UNIX machines can be reached.
EUnet, USENET, ARPA, CSnet, BITnet, MAILnet, DECnet and other networks
(logical or physical) are used as intermediate transport network.

Most intercontinental connections are via the main backbone site (mcvax)
of the CWI in Amsterdam.


EUnet participants
------------------
The sites of EUnet are all a member of the EUUG.
The EUUG provides the structure of EUnet, administrative tools,
responsibility, maintenance and representation.
The EUUG is a non-profit organization.

Originally only universities, non-profit research and development
institutes were EUnet sites.
Due to changes in those sites towards commercial activities
this has changed, so commercial sites are now on EUnet too.
There was no way to avoid this. To give an impression of what
organizations/institutes are connected now to EUnet, a list of
them is attached.
About 85% of the current connected institutes are operating in the
field of computer science and high-tech development.


Current developments
--------------------
Because of the fact that a lot of computer program developments are done
on UNIX-based machines, especially in the network area EUnet will be
influenced by current developments.
Current EUnet experience is recognized and will be used in future network
developments.

EUnet has influenced EEC efforts like ESPRIT. EUnet is prepared to switch
to alternative routes like ISO layering, but only if the software has proved
to be acceptable to take over current tasks; that means is has to be able
to stand the comparison with the current UUCP software regarding such issues
as reliability, automatic routing, flexibility and especially
cost-effectiveness.

At this moment new protocols are tested like MMDF, X.400, ASCnet, etc.


Cost accounting
---------------
In the past DEC provided EUnet with a VAX750 configuration to handle the
central communications. The basic transport scheme for data is "store and
forward". 
This means that intermediate sites (notably the backbone sites) will carry
the data stream. These intermediate sites will only pay for the hardware,
energy and logistics costs.
Due to the fact that there is no site/organization on EUnet that is willing
to pay for all the communication costs an accounting system has been worked
out: all external transport costs will be paid by the receiver and/or sender
of the data.
Normally a sender has only to pay for the (mostly PTT costs) transport of
his data to the backbone site.
The receiver will pay for the costs of sending the data to him.
Since US sites cannot be accounted, European or EUnet sites have to pay for
transatlantic costs themselves. In certain cases (e.g. for getting the USENET
news to Europe) the transatlantic costs are shared amongst all EUnet sites.

The basic charging strategy is top down: the central backbone site (mcvax)
bills the national backbone sites, the national backbone sites bill their
subsites, etc.


EUnet addressing
----------------
Originally the addressing scheme for electronic mail was explicit, i.e.
a full path had to be given, listing all the (interconnected) sites the
mail had to pass to reach its destination. Some time ago an effort was
made to map all sites on the UUCP network and to make the maps available
to all sites on the UUCPnet; that would enable them to provide some routing.
Nowadays this is a well-established service throughout UUCPnet. Despite of
the large number of sites on UUCPnet, it still has been possible to keep
a flat namespace, where every site has a unique name. This routing service
is mainly provided by the backbone sites. Thus any user on the net can now
be reached with an address like "host!user" or "user@host.domain"; in the
latter case the absence of ".domain" defaults to ".UUCP". (Sites with older
software have to prepend "backbone!" to the given addresses).

Due to the influence of ARPA other addressing schemes are going to be made
available in EUnet as well: full RFC822 addressing and some domain addressing.
Besides using the normal UUCP addressing a user can now reach any user on
other networks with an address like "user@site.network".


Other protocols
---------------
Other protocols that are considered now are ACSnet and X.400; as for the
latter: a pilot installation of the EAN software has been done at mcvax,
revealing so many problems that it has been set aside for some time.


Some statistics
---------------
Currently the throughput of mcvax (as the intercontinental gateway for
EUnet) is about 250 Mbyte per month (mail and news). The cost of that
is about $15,000 per month. On the average the transatlantic cost is
about $0.95 per Kbyte over phone links, $0.15 per Kbyte over X.25 links.


Current problems
----------------
Accounting
  Due to missing information exchange between the various software levels,
  the fact that US sites cannot be accounted and the fact that only directly
  connected sites can be accounted, the whole accounting scheme is highly
  an ad hoc scheme. Especially when we're thinking of setting up gateways
  between EUnet and other networks, detailed agreements will have to be made
  about cost charging/forwarding.

Addressing
  Given the way EUnet is set up now, a rather simple domain addressing
  scheme could easily be adapted, where every country has its top level
  domain, named according to ISO standards. This would provide a good
  basis for mail exchange between EUnet and other mail networks.

Protocols
  Though the X.400 standard can be regarded as a good standard for mail
  exchange, extensive attention has to be paid to the data transport level:
  a non-cost-effective transport level can make a brilliant mail service
  useless, simply because it will cost too much. This is especially true
  when setting up links over X.25 PADs, which is commonplace in Europe
  nowadays. New protocols will have to be developed for this; the experience
  gained with the UUCP software can be very useful; the cost-effectiveness
  of the X.25/PAD protocol now contained therein will be hard to beat, in
  fact only by using a full-duplex protocol; the ASCnet software provides
  a basis for that.

Network growth
  It is expected that as soon as a better alternative is available for UUCP,
  making it possible to connect all kinds of systems together, it can be
  expected that the network will get another big impulse. That implies that
  the current policy in UUCPnet of maintaining a flat namespace can no
  longer be held. Therefore a domain addressing scheme will soon have to
  replace the current scheme.

Future
  If one tries to understand what is happening on the computer market,
  as well as the development in hardware and software (smaller, more
  intelligence, cheaper) we have to face the possibility of thousands
  and thousands of users and connected sites.
  This means that new developments should be incorporated and tested
  as soon as possible.
  New protocols and structures have to be defined, and interconnections to
  other networks must be faced.
  Limitations through e.g. homogeneous machine networks, homogeneous
  network by institute goals, homogeneous UNIX networks is a way
  to avoid it, but cannot be considered realistic.
  EUnet will put efforts in better accounting systems, interconnections
  to other networks, and incorporation of new network designs (like
  ISO/IP) and software network standards.


Piet Beertema, CWI, Amsterdam (piet@mcvax.UUCP)
Teus Hagen, ACE, Amsterdam (teus@ace.UUCP)