🚀 go-pugleaf

I will be assisting in the analysis, design, and coding of the
Data Communications area of a new product.  I am a novice in this area
so I have a lot of questions.  I was hoping that the net wisdom could
keep me on track in my quest for Datacom nirvana.  I just have some
very general questions and then as I learn more I should :) be able
to ask something intelligent.

First a very brief description of the task.

 There might be say 100 to 4000 remote sensors collecting data.  These
 sensors might be connected to the central site by dial-up or leased lines.
 The central site is 1 to x unix boxes running C programs that collect
 this data and dump it into a commercial database.  The sensors cannot
 initiate communication with the central site.
	 If the sensors are dial-up they will be called 1 to 4 times per day
 and dump their data (5 to 50K bytes).  If the sensors are on leased
 lines, all sensors will be polled as fast as possible.  In this scenario
 the sensors are just reporting status (short messages, 8 to 50 bytes).
 The leased line sensors will still be asked to dump their data only 1
 to 4 times a day.
    Most of the data going to the sensors is just command messages which
 are short messages.  There are some larger configuration messages
 (1 to 10K bytes) going to the sensors but these don't happen very often.

1. So first of I need some good books to read (tele-communication protocols,
   hardware, etc.).  Any suggestions?

2. I have started reading comp.dcom.modems and comp.protocols.misc.  Are
	there any other groups I should be reading?  There is a mailbox for
	comp.dcom.telecom.digest but it is always empty.  Is this not used? 
	or maybe we are just not subscribed to it.

3. One of the first of my tasks is to develop a protocol for talking to 
	the sensors.  If there exists a wheel to suit my needs, I don't want
	to re-invent it.  Protocol goals:

		Same protocol used for dialup, leased (digital in future?).
		Throughput is of course an issue.
		Data will be DES encrypted.
		The simpler the better.  Although there is a unix box at one end
			there will be a piece of hardware at the other end with very
			limitied cpu power and memory.
		Errorless data.

   For example, a book I'm reading has a couple of paragraphs about
	DDCMP (digital data communications message protocol).  Is this worth
	looking into?  Is it a standard?  I think DEC came up with it. Could
	I use its concepts?  Any info on DDCMP would be appreciated.

	Are there other such protocols I should look into?

4. Cart before the horse.
	Although we are a long time from the design phase I still want to
	start learning about the hardware solutions.  For example, I have
	started coming across "terminal servers" and it sounds like something
	I should learn about :)  If anyone out there would like to suggest
	possible hardware configurations to start me thinking I would 
	appreciate it.

5. What, where (US), and when are the bigger conventions for data/tele
	communications?

6. If someone has an existing application similar to mine I would be
	interested in your solution.


As this project ramps up we will hire a datacom expert but being a 
good boy I would like to be a major contributor so any help will be 
greatly appreciated.  Thanks.



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Jess Sullivan          jess@bally.com