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How multiport print servers work

This post contains some background details on print servers that is hard to dig out today.

Today, the print utility apps from Windows to Linux generally "know" about this stuff and you don't need to care about these details. However, there certainly may be cases where you want to bypass normal printing and get to the printer(s) directly - this may help you if that is your situation.

From: Jeff Liebermann <jeffl@comix.santa-cruz.ca.us>
Newsgroups: comp.unix.sco.misc
Subject: Re: Print servers + ip printing + scoadmin = brain haemorrage
Date: Tue, 12 Oct 1999 09:11:00 -0700
Message-ID: <zVYDOCqDhKHQR741wiYRlwyf1knp@4ax.com> 

On Tue, 12 Oct 1999 18:45:46 +1000, Clint Zikesch <czikesch@mtgl.com.au>
wrote:

>However I am one up on Intel today as I can print to their old XL model using one
>ip address.. which I am told is impossible!  I'll just go read my impossible
>printouts again!  hehe ;)

Perhaps it would help if I explained *HOW* multi-port print servers work.

IP addresses are assigned to interfaces.  An interface is a cute name for
an ethernet port (or a serial port running PPP).  IP addresses are NOT
assigned to devices (printers, computers, servers, routers, etc), only
interfaces.  An interface can be multi-homed and have more than one IP
address, but this is normally not done for print server port selection.

One way print servers select multiple printers is to look for data on
multiple ports.  I don't wanna try and find the Intel docs, but HP EX3
listends on ports 9100, 9101 and 9102, for printer ports 1,2, and 3
respectively.  By definition, these ports are all "raw" and do no
formatting.  This is ilustrated in:
        http://aplawrence.com/cgi-bin/ta.pl?arg=105327
The port numbers change with each manufactory.

Another way is "virtual" printers or port names.  The print server
accepts data on a single IP port (usually 515), and selects the virtual
printer by name.  For HP EX3, this TEXT1, TEXT2 and TEXT3 respectively.
See:
        http://aplawrence.com/cgi-bin/ta.pl?arg=104997
The names can be changed to confuse the innocent.  RAW1, RAW2, and RAW3
are the names used for Postscribble printing.  There are other names.

The virtual printer names also change with manufactory.  If you expect to
have the print server do some formatting (IMHO a bad idea) then the exact
name determines the level of formatting.  Dragged to its extreme, the
Axis 540 print server includes a postscript stripper and an EBCDIC to
ASCII converter.  Usually, the port name is just used for CR-LF
translation.

I have no clue (and little interest) in discovering which ports and
virtual printer names that Intel uses.  I did find a list on the web with
a table of known port numbers and names.  Now, I can't find it.  Argh.
However, the mechanisms for port selection, by IP port number and by
virtual printer name, should be identical for all print servers.

Drivel:   I found this note in the ACITS lpr print client docs.
  Some HP JetDirect devices may not be compatible with LPD printing
  (RFC 1179). The device may need to be updated to a newer version.
  Also, JetDirect devices using firmware revision 03.15 through 04.08
  are known to have problems with control files of certain sizes
  (approximately 99 bytes).  HP recommends upgrading the firmware
  to 04.09 or later.


-- 
Jeff Liebermann  150 Felker St #D  Santa Cruz CA 95060
(831)421-6491 pgr (831)426-1240 fax (831)336-2558 home
http://www.cruzio.com/~jeffl   WB6SSY
jeffl@comix.santa-cruz.ca.us   jeffl@cruzio.com

A follow up post:

From - Wed Oct 13 06:32:29 1999
From: Jeff Liebermann <jeffl@comix.santa-cruz.ca.us>
Newsgroups: comp.unix.sco.misc
Subject: Re: Print servers + ip printing + scoadmin = brain haemorrage
Date: Tue, 12 Oct 1999 09:31:19 -0700
Message-ID: <EGIDOPrlBc=oROt9FIwS3CaGVsBW@4ax.com> 

On Tue, 12 Oct 1999 09:11:00 -0700, Jeff Liebermann
<jeffl@comix.santa-cruz.ca.us> wrote:

>I have no clue (and little interest) in discovering which ports and
>virtual printer names that Intel uses.


Intel prints on ports 3001, 3002 and 2501 for parallel 1, parallel 2, and
serial 1 respectively.


-- 
Jeff Liebermann  150 Felker St #D  Santa Cruz CA 95060
(831)421-6491 pgr (831)426-1240 fax (831)336-2558 home
http://www.cruzio.com/~jeffl   WB6SSY
jeffl@comix.santa-cruz.ca.us   jeffl@cruzio.com

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