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Path: utzoo!linus!philabs!cmcl2!seismo!columbia!topaz!hedrick
From: hedrick@topaz.ARPA (Chuck Hedrick)
Newsgroups: net.lan
Subject: Re: Ethertips
Message-ID: <2879@topaz.ARPA>
Date: Tue, 23-Jul-85 21:13:29 EDT
Article-I.D.: topaz.2879
Posted: Tue Jul 23 21:13:29 1985
Date-Received: Thu, 25-Jul-85 21:00:49 EDT
References: <2394@ut-sally.UUCP> <2451@ut-sally.UUCP>
Reply-To: hedrick@topaz.UUCP (Chuck Hedrick)
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 42

Both the Bridge TCP boxes and the DEC LAT boxes can be used as
either true terminal servers or "milking machines".  That is, you
can have the following:

		user terminals
		\ \ \ / / /
		  --------
		  |      |
		  |      |
		  --------
		     |
	=====================================================
	    |					|
	----------			    ----------
        |        |			    | Host   |
	|        |			    |   A    |
	----------			    ----------
        ||||||||||
	----------
	| Host   |
 	|  B     |
	----------

Host A connects directly to the Ethernet.  It gets packets directly
from the TIP that the users talk to.  Host B does not talk directly to
the Ethernet.  It is frontended by a black box (probably identical to
the TIP) with RS232 output, which goes into the host just like any
other terminal line.  It is useful to have this configuation freedom.
A direct arrangement (A) is least expensive for a machine that is going
to have any Ethernet connection anyway (e.g. for FTP).  The "milking
machine" arrangement makes sense in any of the following cases:
  - the machine is not otherwise going to be on Ethernet, and won't
	need many network connections (e.g. our RSTS system, where
	we just want a couple of TA's at a time to be able to log
	in from our campus net)
  - there are going to be lots of network connections, and the
	host operating system has high overhead for telnet
	connections.  (We won't mention any names here.)
  - the host does not support the protocol used by the boxes
	(e.g. if you decide to use LAT and have a couple of 
	non-DEC machines.  DEC refers to this configuration as
	"reverse LAT").