Network differences

[Ron Natalie <ron>]

>      o What hardware is required for UUCP,ARPA,BITNET,DECNET,MAILNET,CSNET?
>        (Would it be feasable to try to obtain a feed on one of these 
>         networks.  I have heard ARPA requires a very expensive controller
>         and special phone lines so it probably is not for most persons.)
> 
>       o If anythig other than UUCP can be used, what are the advantages to
>         these other netowrks (forgot to include micnet what ever that is.)
> 
UUCP requires as a minimum a incoming modem.  If you don't want to have
to rely on someone else calling you to initiate a transfer, some sort of
automatic dialer is required.  The code is all in user mode and is
available for nearly every UNIX system.  Generally, except when it comes
to NETNEWS, UUCP is very, very, cheap.

ARPANET:  Really the ARPA INTERNET.  This is a collection of networks
using a common protocol which automatically (at least to the user) routes
the data to the required host on the required network through special
hosts called Intenet Gateways.  The per-host cost can be anything from
a simple serial interface to an Ethernet board to something exotic like
a Hyperchanel.  It is pretty nice for campus collection of local area
networks.  The hard part is getting interfaced to the rest of the INTERNET.
This requires some data line to some other part of the network.

To connect directly to the ARPANET there are several different types of
interfaces in use.  DCA the people responsible for the hook ups these
days are heading towards using an X.25 style interface, which would
require a synchronous serial port and some pretty standard modems.
This won't be ready until next summer however.  Currently a specific
serial protocl based on HDH is used over the same hardware.  Companies
like ACC make smart serial cards that do the X.25 and HDH parts for you.
The hard part is getting authorization to get hooked up to the network.
You need to either be contracted for by DARPA for research or have some
DOD site speak up for you and say they require the ability to talk to you.

Since in the past, hosts were frequently hooked up physically near the
IMPs (these are the nodes on the ARPANET) there are two interfaces
(really the same except for the line drivers) called local host and
distant host.  These are typically hooked up to the UNIBUS through
ACC's LH/DH-11.  The price for this is not any more than for a decent
Ethernet card.  The cute part was that ACC built a kludge box that
allowed a host and IMP appear to be plugged into each other even
though they were separated by a synchronous modem.  This strategy
was rather expensive, but for some of us, was the only way to do what
we wanted.

The software for this (TCP/IP) comes with the Berkeley UNIX's.  It can
be had (for a price) for System V and VMS.  The ability to be on the
INTERNET means instant interconnectivity with everyone else, had high
data rates at least on the local group of networks.

BITNET:  BITNET is to the IBM world what UUCP is to the UNIX world.
It also was a creature of neccessity.  Based upon an interprocessor
spooling system called RSCS, the hardware involved is just a serial
line and a couple of modems.  BITNET connections are pretty much dedicated
links, and things are store and forwarded from host to host.  Not
quite as nice as being on the INTERNET but, pretty fast service.
UNIX machines may be hooked up to BITNET by using the UREP package.
I would say the main factor in deciding if you wish to be on BITNET
is to decide if the people you really want to talk to are on BITNET.
BITNET has some pretty far flung nodes throughout ACADEMIA in EUROPE
and the MIDEAST.  IBM uses a similar network between it's internal
sites called VNET, but due to corporate paranoia this net is closed
to all but specifically approved outside accesses.

DECNET:  DECNET is a network protocol/system not a specific network.
You can have DECNET in your facility.  There are corporate DECNETS
that span cities, etc.  DECNET can be used over a variety of network
hardware from serial lines to Ethernet, etc.  Pretty much DECNET
provides the same functions as the ARPANET, but it is very, very
specific to DEC hardware.  In addition, the deciding factor is how
to interconnect your DECNET to the rest of the world.  DECNET support
has been rumored for the next ULTRIX release.

MAILNET:  I'm not sure of this one, but it appears to be a collection
of dial up hosts somehow gatewayed to the US through Multics.  I just
mail to them through there, rather than bothering worrying about being
on MAILNET.

CSNET:  CSNET has two modes of operation.  The first is over TCP/IP
style connections involving the ARPANET and a TCP/IP over X.25 project.
The other older mode of operation is a dial up protocol using Dave
Crocker's Phonenet protocol (please, don't say MMDF, MMDF is the mail
queing system and is separate form the Phonenet protocol, you can use
either without the other).  The CSNET relay machine calls you up and
transfers mail to you.  In addition, CSNET has several server functions
such as a white pages directory.  Of course, this all isn't free, it
costs to be on CSNET, but it does give you a good working and legal
connection to the ARPANET for mail at least.

-Ron