Re: [TCLUG:9256] print server concepts

[Christopher McKinley <lamfada@lugh.net>]

Tim Wilson wrote:
> 
> Hi everyone,
> 
> Here's a question that I've been wondering about off and on. I figure it's
> something that other people would probably be interested in too. So here
> goes...
> 
> Let's say we have a simple LAN, 'server', 'workstation', 'printer', and
> 'printserver.' The printer has a JetDirect card (i.e., its own internal
> print server). I'm trying to figure out the basics of how the network
> printing works. I understand that, strictly speaking, the JetDirect card
> eliminates the need for a special print server (especially given the
> simplicity of this example). But I've also heard that more complex
> networks benefit from having a separate machine doing the print serving to
> the JetDirects.
> 
> Anyway, here are some questions.
> 
> 1. Does 'workstation' have to run lpd, or just 'printserver'?
> 

You can either have all workstations run lpd, in which case all
workstations must have the /etc/printcap to tell them about the
printers.  This way all filters are run locally (i.e., PostScript to
PCL, ASCII to PostScript), but you have to maintain all of the lpd
instances and update filters, etc.  Another way to do it is to use the
-Pprintername@printserver option to lpr, and then the conversions will
be run on the print server if everything is setup correctly.  Something
I have not tested yet is mix and match of filter settings, i.e., lpd
running on workstation with or without filters.  I currently use filters
on the workstation and server.  Something to test?

> 2. Does having one print server for multiple printers mean simply that
> there are multiple print queues on that machine or is it more complicated
> than that?
> 

I have not used multiple printers connected to the same print server
under Linux, however the LPRng docs do cover that, and yes, each printer
has its own queue, and also its own printcap entry, so that, for
example, I can run one set of filters for my PostScript printer and
another for my PCL printer.

> 3. How would a print server print to multiple printers if the printers
> don't have JetDirect cards (or the equivalent)? Would you have multiple,
> physical parallel connections to the printers? If so, wouldn't that mean
> that all of the printers would have to be physically close to one another?
> 

I can not give a tested answer, but it would really depend on the
printers.  You could, for example, put a parallel card in the print
server to print to multiple parallel printers, or a better solution that
allows printers to be geographically separated is to use a central print
server, which "knows" which workstation / server has which printer. This
way, hplj4ml-first-floor@printserver can map to
hplj4ml-dept-a@dept-a-wkst-1 and hplj4ml-second-floor@printserver can
map to hplj4ml-dept-b@dept-b-wkst-1, for example.

> 4. To configure printing to 'printer', would I set up printing to
> 'printserver' and have that redirect printing to 'printer'?
> 

Basically, yes.

> For whatever reason, I haven't got the hang of this network printing stuff
> yet. What I've got running works, but I feel like I don't understand it,
> and I'd like to add another printer and make everything work well
> together. Any other hints?
> 

I am using LPRng, newly recompiled from sources with magicfilter-1.2. 
The LPRng docs are pretty good, especially if you already have a working
setup to modify.  The printcap and filters should be the same though, no
matter which lpr you are using.

> -Tim
> 
> --
> Timothy Wilson       | "The faster you  |  Check out:
> Henry Sibley H.S.    |  go, the shorter | http://slashdot.org/
> W. St. Paul, MN, USA |  you are."       | http://linux.com/
> wilson@chem.umn.edu  |       -Einstein  | http://www.mn-linux.org/
> 
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