[][][][][][][][][][][][][][][][][][][]
[]         THE INS AND OUTS         []
[]                OF                []
[]         PACKET SWITCHING         []
[]                                  []
[]     by:       The Seker          []
[]         Tribunal of Knowledge!   []
[][][][][][][][][][][][][][][][][][][]
[]    Written (c)  June 23, 1986    []
[][][][][][][][][][][][][][][][][][][]

                         'TRIBUNAL COMMUNICATIONS LTD'
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
     Not many people are quite aware how complex packet switched
networks are.  In this file I hope to clear up all confusion and
answer all questions concerning packet switching and making
international datacalls via packet switched networks.

HISTORY
=======

     Using normal phone lines, computers can only transmit data at
speeds up to 1200 bps efficiently.  This is very slow compared to the
inner workings of even the slowest computer.  If computers could
transmit across phone lines at higher speeds, 9600 bps for example,
there would still be the problem of using a compatible protocol.
Packet switched networks take care of these and other problems
dealing with communications.

     The idea of developing a completely computerized network for
computers was first discussed in the mid 1960's..probably someplace
like Bell Labs, MIT, or the like.  But it wasn't until a decade later
that the theory was put into construction.

     The first packet network was a project of the Defense
Department.  They labeled it ArpaNet.  It was and still is a boon for
advanced hackers, as it is host to over 300 government related
computers.  (See 'Hacking ArpaNet' written by the Wizard of ArpaNet
for an indepth look at breaching this system.)

     Today there are over five commercial packet networks in the
United States alone (Telenet, Tymnet, CompuServe, etc), and many more
throughout the world.

HOW IT WORKS
============

     In essence, packet switching services operate at 4800 bps full
duplex (both direction simulstaneously) and use a form of TDM (Time
Division Multiplexing), a transmission which is basis for most of the
world's voice communications.  Transmission streams are separated
into convenient sized blocks or 'packets', each one of which contains
a head and tail signifying the origination and destination of the
data.  The packets are assembled by either the originating system or
by a special facility supplied by the packet switch system.  Packets
in a single transmission may follow the same physical path (same
cable) or may use an alternate route (ie. a detour cable) depending
on the congestion of the system.  The packets from one 'conversation'
are very likely to be interleaved with packets from other
'conversations'.  The originating and receiving computers see none of
this mixing.  At the receiving end, the various packets are stripped
of their routing information, and re-assembled in correct order
before presentation to the computer terminal.

     All public networks that use packet switching have installed a
standard protocall to try and be compatible with each other. (good
luck)  The standard, which is called CCITT X.25 (Developed at the
Geneva conferences.), is implemented on all international datacalls.
This is a complex system for interface between data terminal
equipment and data circuit-terminating equipment.

ACCESSING
=========

     Users (hackers) can access packet switching in a variety of
ways.  Special terminals called Packet Terminals, which are usually
hard wired to the nearest PSS (Packet Switch Stream), that are able
to create and arrange data into the correct format are often used.
This is very expensive, a reason why you will only be likely to see
these type of terminals within large company office buildings.  The
average person will probably access a packet network using an
ordinary ascii terminal (computer and modem), and connect to a
special PSS facility called a PAD (Packet Assembler/Disassembler)
which will handle the formatting for them.

USING
=====

     To use a public packet network it is usually required for one to
have a NUI (Network User Identity) which is registered at your local
PSE (Packet Switch Exchange) for billing purposes...or a way around
this.

     Dial into your local PAD (often called port) and enter your NUI.
If a valid ID is not given, the port will usually throw you off.
(There are a few exceptions which we will discuss later.)  Then one
enters the NUA (Network User Address) or call name of the computer
he/she wants to access.  Each computer on a network has one given to
them.  This is usually in the form of numbers or somtimes letters.
(As in Tymnet's case.)  After the correct information is entered, the
network will connect you via its private sattelite system to the
local phone system of your destination and then onto the computer you
wish to access.

BILLING
=======

     Billing on networks is done to either the user or reversed and
charged to the designated computer.  Charging is not done according
to the distance of the call or by the time passed, rather by how many
packets exchanged and sometimes a small fee for CPU (Centeral
Processing Unit) time.

     Many packet networks do not require you to have an NUI at all.
One of these that many of you probably have worked with is Telenet.
It is a leading public network throughout the continent.  Billing on
there is a variation of the norm.  There is only a charge to a user
when he/she wants to access a computer internationally or one which
doesn't accept the charges of the datacall. (ie. REFUSE COLLECT
CONNECT 00 AA)  Billing like this will probably disappear soon due to
the greed of big business.

INTERNATIONAL DATACALLS
=======================

     If a person wishes to call a computer located on a foreign
network, there is a little procedure which must be done.  As I said
earlier, each computer on a network has its own address. (NUA)
Networks also have their own 'address', which is called a DNIC. (Data
Network Identification Code)  This code is four numerical digits
long.  The first three numbers in this code represent which country
the network is located in.  The fourth digit is which service in that
particuliar country, as some countries have more than one network.
(For example, 5052 is Australia's Auspac DNIC.  505 is the country
code.  2 is the service code.)  A list follows:

 COUNTRY                 NETWORK                  DNIC
-------------------------------------------------------
 Australia               Auspac                   5052
 Australia               Midas                    5053
 Belgium                 Euronet                  2062/2063
 Canada                  Datapac                  3020
 Canada                  Globedat                 3025
 Canada                  Infoswitch               3029
 Denmark                 Euronet                  2383
 France                  Transpac                 2080
 France Antilles         Euronet                  3400
 Germany (West)          Datex P                  2624
 Germany (West)          Euronet                  2623
 Great Britain           IPSS                     2342
 Hong Kong               IDAS                     4542
 Irish Republic          Euronet                  2723
 Italy                   Euronet                  2223
 Japan                   DDX-P                    4401
 Japan                   Venux-P                  4408
 Luxembourg              Euronet                  2703
 Netherlands             Euronet                  2043
 Norway                  Norpak                   2422
 Singapore               Telepac                  5252
 South Africa            Saponet                  6550
 Spain                   TIDA                     2141
 Sweden                  Telepak                  2405
 Switzerland             Datalink                 2289
 Switzerland             Euronet                  2283
 USA                     Autonet                  3126
 USA                     CompuServe               3132
 USA                     ITT (UDTS)               3103
 USA                     RCA (LSDS)               3113
 USA                     Telenet                  3110
 USA                     Tymnet                   3106
 USA                     Uninet                   3125
 USA                     WUI (DBS)                3104

     As you can see, the the United States has many services.  But
their DNIC doesn't follow the pattern I described earlier. (ie. first
three digits represent country, last is service)  I am not quite sure
why this is, but I think it may be because each of the US services
listed are privately owned.

     As I was saying earlier, there is a little extra bit of
information you must give the network when making an international
call.  Instead of just emtering the NUA like on a domestic call, you
have to enter the DNIC and append the NUA or you will not complete
you call and probably will get an error code.  Here is what a call
from Telenet to Cambridge University's port selector in England,
which is located on Euronet (In Britain they call it IPSS.) would
look like:

TELENET
714A

TERMINAL= d1

@ ID EXAMPLE
PASSWORD? 

ID VALID

@ c 234222339399

CONNECTED TO 234 222339399

     What I just did was connect to a Telenet port.  Enter my NUI.
Then enter the DNIC for IPSS in Britain (2342) and appended the NUA
for Cambridge University. (22339399)  Then I was connected.

REFERENCES
==========

     For more detailed info on packet switching and its uses, etc, I
recommend the following two books:

 'Data Communications: Facilities, Networks, and Systems Design'
  Doll, Dixon R., New York, Wiley, c1978

 'Packet Radio'
  Rouleau, Robert and Ian Hodgson, Blue Ridge Summit, Pa., Tab Books,
c1981

ACKNOWLEDGEMENTS
================
     Much of the imformation within was provided by:

 Cyclone II
 Slave Driver

 NOTE: This document was written for informational purposes only.
Any application of what was provided within is responsibility of the
user, not the author.

        >>>>>>>>>>>>>>> (c) 1986 TRIBUNAL OF KNOWLEDGE! <<<<<<<<<<<<<<<
