Path: utzoo!attcan!uunet!convex!dpz@convex.com
From: dpz@convex.com (David Paul Zimmerman)
Newsgroups: comp.dcom.lans
Subject: Re: Termservers for printers (How to?)
Message-ID: <1524@convex.UUCP>
Date: 12 Aug 89 22:41:39 GMT
References: <7130@spsd.uu.net>
Sender: news@convex.UUCP
Distribution: na
Lines: 37


We've got some printers connected through cisco terminal servers, and they
work pretty much OK.  The setup is:

lpd -> ttypN==ptypN -> "lp_pty" -> cisco port X==printer

where -> is a tenuous path, and == is a fairly reliable hard path.  The
sequence of events:

	- lpd talks to the tty side of the tty-pty pair
	- a program "lp_pty" reads from the pty side of the tty-pty pair
	- you can open a raw TCP connection to a particular port on cisco term
	  servers, and have the data come out on any particular serial line.
	  At startup, lp_pty opens up a connection to the cisco term server on
	  port 4000 + the decimal number of the serial line.
	- lp_pty writes the data over the TCP connection
	- the cisco term server reads the data and stuffs it down the
	  requested serial line
	- the printer gets the data and does whatever it is supposed to

Details to get this going include renaming a tty=pty pair to something that
telnetd and rlogind can't find (like printername-ttysf, printername-ptysf).
lpd talks at the tty side.  You then run "lp_pty" with arguments to tell it
what pty to read from, what host to open the TCP connection to, and what port
to open it at.

I mentioned a tenuous path vs a hard path above because once in a while I have
to go through and kill/restart everything, because something along the way
just stops.  I think it is lp_pty, so I have to work on it a bit.

Of course, acknowledgements: L. Ron Natalie @ Rutgers University took 'telnet'
and munged it around to become 'lp_pty'.  I took it :-)

						David

David Paul Zimmerman                                             dpz@convex.com
CONVEX Computer Corp                                                 convex!dpz