From: toupine@ciaibbs.Colorado.EDU (edward toupin)
Subject: BROADCASTS ON ETHERNET
Originator: toupine@ciaibbs.Colorado.EDU
Organization: University of Colorado, Boulder
Date: Mon, 13 Apr 1992 04:15:02 GMT

comp.os.vms
comp.dcom.lans
comp.dcom.lans.ethernet

==========================================================================
BROADCAST COMMUNICATIONS VIA ETHERNET
==========================================================================
This posting is a general brainstorming posting.  I am looking for 
experienced ethernet network programmers to offer advice and 
related problems involved in performing "broadcast process 
communications" (for lack of a better term).  Below is an explanation.
More information is available if required.  Please reply by
email if possible.f

I am working under VMS 5.5 on VAXStation 3100 and 4000 machines
in an ethernet networking environment.

==========================================================================

I.	SITUATION	:

	I currently have a series of processes in a real time 
	environment that communicate via transparent interprocess
	communications.


						------------
	------------		Channel x	
		    ----------------------------  CLIENT A  
	  SERVER    				
		    ----+			------------
	------------	|			
			|
			|
			|			------------
			|	Channel y
			+----------------------	  CLIENT B

						------------

	This situation is accomplished by using the standard SYS$ASSIGN
	followed by SYS$QIO's to two seperate channels.


II.	RESEARCH	:

	I have developed several applications for network monitoring
	and loopback testing on the network.  I can build and
	submit packets to the network without any problems.

	This research involves connecting to a network card 
	using promiscuous mode and using SYS$QIO to submit and
	or receive packets.

	I am aware that you can establish a channel to a card and disable
	promiscuous mode in order to have one particular protocol handed
	to your process.  This protocol is defined in the SETMODE portion
	of the channel's setup. I have had a little trouble with sending
	a packet from PROCESSA and receiving it by PROCESSB.

III.	PROPOSED MOD	:

	I am looking at taking the processes mentioned in section I
	and converting them to a type of broadcast situation where
	one packet may be sent from a server and received by multiple
	clients.

			      Network
				[]
	+-------+		[]	+-------+		
	|	|---------------[]------|	|
	| Srvr	|		[]	| ClntA	|
	+-------+		[]	+-------+
				[]
				[]
				[]	+-------+
				[]------|	|
				[]	| ClntB	|
				[]	+-------+
				[]
				[]
				[]	+-------+
				[]------|	|
				[]	| ClntC	|
				[]	+-------+
				[]
				[]
				[]	+-------+
				[]------|	|
				[]	| ClntD	|
				[]	+-------+
				[]

	The ideas is to submit one packet to the network using, lets say,
	protocol 6006.  All clients would pick up the packet and process 
	it accordingly based on certain characteristics of the data
	within the packet.



==========================================================================


QUESTION	:

	Has anyone worked with broadcasting messages to client processes?

	If so, I would like to hear your ideas, suggestions and problems.

	If more explanation is needed, please feel free to send email
	at your convienience.

Thanks in advance,

Ed Toupin
toupine@ciaibbs.colorado.edu	






Xref: sparky comp.dcom.lans.ethernet:557 comp.sys.sun.misc:1795