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swskit-v21/documentation/learning-decnet.mem
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|d|i|g|i|t|a|l| INTEROFFICE MEMORANDUM
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TO: DECnet SWSkit DATE: 1-APR-82
FROM: NCSS
EXT: HOTLINE (8-231-5911)
LOC/MAIL STOP: MR1-2/H22
SUBJ: Self-Study Program for Learning DECnet
This memo attempts to describe a scheme for learning DECnet if
you've had no experience with networks before.
The best way, and the quickest, to pick up DECnet is to attend the
courses offered by Educational Services. There are several
appropriate courses offered. If you do end up in Bedford for
training, try to setup a visit with NCSS for a couple of days
afterwards. We can get to know each other and you can see what we
do.
Unfortunately, we know that many times specialists don't get sent
to courses in a timely way and it becomes necessary for them to
pick things up on their own. If this happens, the general outline
given below may be of help. Feel free to adapt this to your own
particular needs.
This memo makes many references to documents. For more detailed
information including order numbers, refer to
DECNET-DOCUMENTATION.MEM elsewhere on this SWSkit.
1.0 LEARN GENERIC DECNET CAPABILITIES
First get an idea of what DECnet is all about from a
product/program point of view. The following materials might be a
help.
1. Introduction to Minicomputer Networks (a Digital handbook)
2. Introduction to DECnet self-paced course
3. DECnet Marketing Guide
Page 2
4. Any available Customer Support Plans and Network Profiles for
sites in your district
2.0 LEARN THE CAPABILITIES OF THE CURRENT RELEASE
This part of the learning process will help you a lot in presales
situations. Find the appropriate SPDs for the current release of
DECnet and learn them! In addition, take a look at the current
DECnet-20 Programmer's Guide and Operations Manual -- this will
tell you what programs and features are available and supported.
A look through this SWSkit may give you an idea of what kinds of
applications can be written, but remember that any programs on
this SWSkit are not supported.
3.0 LEARN USER LEVEL CAPABILITIES
For this step it will be almost essential to have access to a
DECnet-20 system to experiment with. Read the DECnet-20 manual
and try experimenting with the information given. Learn what can
be done with NFT/FAL. A very important part of this step is to
write a simple DECnet application program. This may be as simple
or as complex as you desire; the purpose is simply to get a
handle on the JSYS's which are used to implement DECnet programs.
One simple example of what can be done is a program which opens a
link as a server and then waits for input. When text is sent to
it over a logical link it types it on the terminal. Such a
program can be easily tested, because the EXEC COPY command can be
used to send text to the program, and the accuracy of the data
transfer can be quickly determined. In addition, if the server
program is written first and the EXEC is used to communicate with
it, you have only one program to write and debug at any given
time. Once your server program is written you can write another
application which might communicate with the server in a more
elaborate fashion.
4.0 LEARN SOMETHING ABOUT COMMUNICATIONS HARDWARE
You don't have to double as a field service person, but it is
useful to know about the modem signals involved in DECnet
communications and to have a fairly good idea of how the line
drivers work. A very good reference for this is McNamara's book,
Technical Aspects of Data Communications. This should be
available through the Digital Press. Don't worry about trying to
understand all the electronics details in this book, but try to
get a handle on what the various modem signals, like DTR and DSR,
are used for. At this point it's also a good idea to take a look
at the PDP11 Terminals and Communications Handbook. This
Page 3
describes all the line drivers used by DECnet (plus many others
not used by DECnet). A very good course to take at this point
would be the Communications Interfaces and Modems Workshop.
5.0 DO AN INSTALLATION
Unfortunately, this is probably the step most specialists will end
up doing first, whether they're prepared or not. Try to get a
handle on the "big picture" that each step is a part of, rather
than just following the steps by rote. An installation is
probably your best chance to learn the operator commands for
DECnet, which are provided by the NCP subset of OPR.
6.0 TAKE A LOOK AT PROTOCOLS
If you've managed to get this far through the learning process
without losing interest or running out of time, it's time to take
a serious look at the protocol specifications. The protocols of
greatest interest are DDCMP, NSP, DAP, and MOP. Specifications
are available from the SDC. Once you think you have an
understanding of the specs, it can be instructive to try to write
down, on paper, what a particular DDCMP or NSP message will look
like. Then verify your prediction with a Datascope, if you can
get one. DNSR can be used to dump NSP messages passing between
the DN20 and the KL for learning purposes.
The reason the protocols have been ignored until this point in the
learning process is because the protocol details can get in the
way of learning more useful things. Most of the questions we have
seen from the Hotline have been basic questions about what the
product can do. It is our feeling that, once the product is in
the field, most of our problems will come with installation
procedures or questions about the basic functions provided. It is
not necessary or even desirable to get deeply involved with
protocol details until these other things are understood.
7.0 LEARN THE CODE
This is strictly optional for field specialists. The sources are
either supplied on the release tape, or listings are available on
the DECnet SWSkit. It would probably be easier to start with the
-10 code -- NSPSRV, NSPPAR, NSPINT and KDPSRV monitor modules,
NETCON sources, and network file transfer sources
(NFT/FAL/DAPLIB).
Before attempting to tackle the MCB code, it might be advisable
for the specialist to learn something about -11M, since the DECnet
front end is based on a system similar to RSX11M. If possible,
find an -11M system and play with it as a user, and learn enough
Page 4
of -11M macro and the task builder and utilities to write a simple
assembly language program. The -11M support course offered by Ed.
Services would be a good choice here, if you can get to it. Then
you could tackle the MCB listings supplied on the SWSkit, placing
emphasis on the NETACP code, the NSP modules and the Comm Exec
subroutines. The file
8.0 BECOME FAMILIAR WITH BLISS
If you plan to repeat this whole process for future releases of
DECnet, it would be advisable for you to become familiar with
BLISS while DECnet release 2 is in the field. Future releases of
the DECnet code will use BLISS extensively.