Loopback vs. Dummy?

Loopback vs. Dummy?

Post by Dag Bratt » Thu, 13 Jun 1996 04:00:00


Can somebody out there tell me the difference between the linux
loopback device (lo) and the linux dummy device (dummy).

I really can't see the difference from a user point of perspective. By
using ifconfig on the dummy device I can configure it to any IP-address I
like so what do I need the dummy device for?


-- Dag


/// University of Tromsoe  // Phone: +47 776 44591       //
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1. Parallel loopback, or dummy printer load

We're in need of a parallel port loopback, or some kind of dummy printer
load, for testing a Sparc20 system that we manufacture, for RF emissions.
We have tested PC systems before with a simple loopback plug, but trying to
use this on the SS20 parallel port isn't working.  We've looked at it with a
scope on a breakout box, and with the PC loopback plug in place, the printer
driver sends just the first byte, then stops.  If we connect a real printer,
there doesn't seem to be anything different about the SS20 data signals from
PC data signals.

We can't actually hook a printer up to the system, because the RF from the
printer interferes with the measurements taken from the SS20 chassis.

Any ideas?  Casper, do you know what kind of pin-out a loopback connector
would need? :)

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