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what hardwares does conserver support?

Doug Hughes doug@gblx.net
Wed, 23 Jan 2002 07:40:28 -0700 (MST)

On Tue, 22 Jan 2002, Greg A. Woods wrote:

> The correct solution is to modify the console serial port on the host
> system such that the system itself will supply a data signal in the
> absense of a signal from the attached terminal or terminal server, while
> at the same time not preventing the terminal server from generating a
> real BREAK signal on demand.  One way of doing this is to putting an
> approximately 4.7K Ohm resistor between pin 3 and pin 25 (which has -5v
> on most Sun systems) on the host end when connecting to a Sun SPARC
> host.  This should have the effect of stifling any appearance of a BREAK
> signal when the console server machine is either disconnected or power
> cycled.  However so long as the terminal server can still send data it
> should also still be able to send an intentional BREAK signal as well.
> (contrary to the incorrect information on the Cisco page -- obviously if
> the resistor held the Rx pin at the mark level permanently then no data
> could be sent at all to the port, and similarly if the terminal server
> can still toggle the line levels to send data signals then it can
> equally well hold the line at the space level for the requisite time to
> generate an intentional BREAK signal).
... <electrical specifications elided>
> The other solution is of course to just use a reliable enough terminal
> server and never power cycle it, and also of course never disconnect the
> console cable on a server that's in production (schedule downtime
> first!).  On my home network I use a DECserver on a DEChub500 with
> redundant power supplies.  :-)

I would swap these around. I would start with a good terminal server
that doesn't send false breaks when power cycled. The cisco 36XX series
is one such. You can power cycle the box all you want and it will not
send a break during such an event. There are others popping up
Perle -
Digi, Lantronix, Xyplex
(see evals: http://www.datacomideas.com/SunSafe.html)

If I was going to buy one today (and my company wasn't strongly
wedded to Cisco already), I'd get one of these:
They have an optional module that is controlled by a cable from
the console server that allows you to power cycle the host as well.

Also see NuData's product, which you can plug into the serial port
of a Sun to prevent erroneous breaks:

I realise the point that Greg is trying to make, but, IMHO, one should
try any/all of the above solutions long before taking the possibility
warranty voiding and manual act of soldering components onto your
serial port hardware. These vendor solutions have been evaluated by
third parties and determined to work.

PS - not since sparc1 days have I had any trouble disconnecting the
serial cable from the Sun side of serial connection. No breaks.