[c-nsp] Splicing a roll-over cable

[Jay Hennigan]

Steve Bertrand wrote:
> Hi all,
> 
> I've finally got some new routers in that I'll be using for testing (the
> IPv6 BGP route-reflector situation is on the top of the list).
> 
> The lab area is very close to my workstation. Before I have the devices
> connected to a network, I prefer to use my workstation to copy config
> snips et-al to the devices.
> 
> Oftentimes, I'll use a lab pc to do similar jobs, so I unplug the
> console cable from the device from my workstation serial port and
> connect to a lab pc serial port.
> 
> I don't know much (ie. anything) about the electrical properties of a
> serial pc interface, so I thought I'd ask whether it would do any harm
> to 'splice' into a roll-over cable so the input/output from the console
> can be used simultaneously from multiple command stations, without
> having to do the physical unplug/replug.
> 
> Essentially, I'd like keystrokes to be seen on one monitor that is
> connected to the console that is typed on another device connected to
> the same console port.

RS-232 drivers should have sufficient current to drive two receivers, 
but two drivers in parallel will tend to pull the line in opposite 
directions.

In other words, if you connect the router's send line and ground to both 
monitors, the output can be displayed on both simultaneously.  You 
probably won't see the command input on the second one, however.

Two keyboards driving the router isn't going to work well, probably not 
at all.

VNC on the PCs might be a better choice to solve this problem.

--
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
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