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From: scarter@caip.RUTGERS.EDU (Stephen M. Carter)
Newsgroups: comp.dcom.lans
Subject: Re: Milking machine performance/function
Message-ID: <3958@caip.RUTGERS.EDU>
Date: Tue, 2-Dec-86 12:00:14 EST
Article-I.D.: caip.3958
Posted: Tue Dec  2 12:00:14 1986
Date-Received: Tue, 2-Dec-86 20:24:26 EST
References: <1612@batcomputer.tn.cornell.edu>
Reply-To: scarter@caip.UUCP (Stephen M. Carter)
Distribution: na
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 55

In article <1612@batcomputer.tn.cornell.edu> swb@batcomputer.UUCP (Scott Brim) writes:

>Once again the only contenders I know of are Bridge, Cisco, and
>Encore.
>Is anyone using terminal servers in this mode?
>

We have a couple CS/100s acting as milking machines to some Prime 9950s
and a Comten.  We are about to replace the CS/100 with a cisco box for
the Primes.  In theory, the Bridge family has excellent parameters for
RS232 ports in milking machine style:
	
	- when a port is set "device=host", it will turn off the welcome
	  message and not allow the connected device to start a session
	  (this is handy of you ever seen an instance where two machines
	  start a tug-of-war with banner messages)
	- supports hardware handshaking in a number of ways, ie you should
	  have no problems with using full handshaking to the extent
	  that the user can't tell the difference between this and a real
	  telnet connection
	- allows sockets to answer to rlogin (does not implement rlogin,
	  bit will connect via telnet).  Also, you can sysgen a port to
	  answer any socket you wish, ie if you wanted to write a SMTP
	  server to reside on a rs232 port.
	- setting an IP address to either a single port or a defined group
	  of ports
	- the usual large selection of speed, parity, stop bits, flow control,
	  and all the rest (see C. Hedrick's article).

We are replacing the cs/100 with a cisco because there are problems.  The
worst design flaw of the cs/100 is the tiny buffers.  In cases where we
have all 14 ports of a box milking a host, we have cases where a connection
will break if the user attempts to type a large file without paging.
(hardware flow control will not help and we can't use ^S^Q because of
emacs). We see this most often on connections from a Unix machine to a port
and not so much from another Bridge port on the network.  We believe that
the Unix machines ask for a much larger window than another Bridge.  We
have made repeated requests to Bridge to help us out with no success.  The
marketing folks stand firm on one release per product and refuse to have a
version that is tuned for milking machines, or make use use of additional
memory on the newer versions of the hardware.  From what I have noticed,
this should only be a problem when you have a cs/100 and a number of ports
on that unit milking a host.  I assume that things would be better on a
cs/200.  Don't know about a cs/1.  We have two ports on one box connected
to a 11/44 where the remainder of the ports are office terminals with no
reported problems.  Newer versions of the software and firmware fix many
oddball bugs that show in this mode.  Get the lastest versions.

I'll post a message about our results of using a cisco box as soon as we
hook it up in about week or so.  Let me know it you want more info.


-Stephen Carter
uucp:   ...{harvard, seismo, ut-sally, sri-iu, ihnp4!packard}!topaz!scarter
arpa:   SCARTER@RUTGERS or SCARTER@RED.RUTGERS.EDU