[cups] Colored dots along the pages

[Gerhard Strangar]

Johannes Meixner wrote:

>>> The backend used is IPP with socket on port 9100.
> This does not make sense.
> Either you use the IPP protocol or plain socket data transfer
> and port 9100 is usually not used for the IPP protocol, cf.

I got misled by the web interface, after clicking "add printer", it
wants me to choose a protocol in step 1 of 5, but apparently, it doesn't
even matter, what I select here, it seems to consider the input from
step 2, only.

>> I changed the backend to LPD, feeding it directly to the lpd
>> port on the printer and the test pages look perfect.
> Basically you tell that the bytes (or more precisely some bits)
> of the actual printing data that arrive at your printer device
> change depending on what backend you use.

That's what I thought, but it misconducted the tests. I did not use the
CUPS internal test page, but something that prints a lot faster. If I
print the internal test page, I get the dots again.

> Perhaps your particular printer device has some weird issues
> when it gets the actual printing data via IPP protocol?

The printer is a Lexmark CS310dn, but I printed more than 800 pages via
FreeBSD's lpr without any problems and also several pages via CUPS
without problems.

I tried
socket://laser:9100
ipp://laser/ipp/
lpd://laser/ps

Right now, I think it's some bug in the printer. However it's
content-dependant and for some reason the CUPS test page triggers it,
whereas others do not. But I just managed to trigger it without using
CUPS. So let's consider this solved.

Thanks,
Gerhard