On the socket 9100 I misunderstood "localhost", because my OS systems run as "localhost" I thought 127.0.0.1:9100 would be the needed string.
Looking at the Status Page from the laserjet 2300dn I noticed it had
hostname: NPI9FE6CE
IP Addres: 192.168.1.4 < ---- now it does

Using the following: socket://192.168.1.4:9100 will do the trick. For some reason using
NPI9FE6CE did not work. Hmmmm....-- how is it now one finds all hosts on a LAN. I have even posted on that, grrrrr

That was too much with that puzzle. I installed "traceroute" and found that the
hostname of the printer:
[root@localhost gert]# traceroute 192.168.1.4
traceroute to 192.168.1.4 (192.168.1.4), 30 hops max, 60 byte packets
1 NPI9FE6CE.local (192.168.1.4) 1.564 ms 2.035 ms 2.479 ms
[root@localhost gert]#
Now, that was not indicated on the status page from the printer. I am using the following in CUPS and that works fine too. Could probably have been fixed with a "hosts" entry.
socket://NPI9FE6CE.local:9100
Added notes for myselfReading the Manual I found that the printer has embedded webserver great number of details can be accessed by using Konqueror Web Browser, seems Opera fails to respond, this just brings up CUPS Web page?? The Webserver is a bit slow but easier to handle than the printer panel itself.
Further a fair bit of work trying to find out why this high end printer insists on delivering paper from tray 2 when I want it from tray 1, that is ridiculous. Tray one is an easy single feed or few sheets feed and I like to be able to feed a single sheet through, for example to add a couple of extra sections to an existing page, having to pull out a bigger difficult tray to force selection to go to the last remaining source of paper
I even went and downloaded the HPLIP and fished out the ppd files for the printer, but this turned out to be same as already available via repo. Did a bit comparison between the files. I don't quit understand the programming inside. Could not convince myself how the the decision on what tray was going to be used was made.
[gert@localhost Downloads]$ lpoptions -p Laserjet2300dn-PostScript-1 -l
HPOption_Tray3/Tray 3: *False Tray3_500 Tray3_250
HPOption_Duplexer/Duplex Unit: *True False
HPPaperPolicy/Fit to Page: *PromptUser NearestSizeAdjust NearestSizeNoAdjust
InstalledMemory/Total Printer Memory: *32MB 48MB 64MB 96MB 160MB 256MB
HPStraightPaperPath/Use Straight Paper Path: True *False
Smoothing/Resolution Enhancement: *PrinterDefault On Off
PageSize/Page Size: Letter LetterSmall Executive DoublePostcard Legal LegalSmall *A4 A4Small A5 ISOB5 B5 w612h935 w558h774 Env10 EnvMonarch EnvDL EnvC5 EnvISOB5 Custom.WIDTHxHEIGHT
MediaType/Media Type: *None Plain Preprinted Letterhead Transparency Prepunched Labels Bond Recycled Color Rough Card_Stock Envelope
HPBookletFilter/Format Output As Booklet: True *False
HPBookletBackCover/Last Page Is Back Cover: True *False
HPBookletPageOrder/Page Order: *Normal Asian
HPBookletScaling/Scaling: *Proportional FitPage
HPBookletPageSize/Paper For Booklet: Letter LetterSmall Executive DoublePostcard Legal LegalSmall *A4 A4Small A5 ISOB5 B5 w612h935 w558h774
InputSlot/Paper Source: Auto *Tray1 Tray2 Tray3_500 Tray3_250
ManualFeed/Tray 1 (Manual): True *False
HPHalftone/Levels of Gray: *PrinterDefault Enhanced Standard
Resolution/Printer Resolution: 1200x1200dpi *1200dpi 600x600dpi
HPEconoMode/Economode: *PrinterDefault True False
Duplex/2-Sided Printing: *None DuplexNoTumble DuplexTumble
[gert@localhost Downloads]$
The red shows that I have default input slot for Tray 1, and there is paper in the tray. This printer does not have a Tray 3 (false)
The command below allows me to move the default input slot, I tested with using Tray2 and the * moved. I am not sure what takes precedence cli or ppd.
[gert@localhost Downloads]$ lpoptions -p Laserjet2300dn-PostScript-1 -o InputSlot=Tray1
[gert@localhost Downloads]$
The main test was printing a page as follows, because of the simplicity. CUPS had set the defaults beforehand
[root@localhost gert]#lp -d Laserjet2300dn-PostScript-1 /usr/share/printer-testpages/testpage.asc
In desperation I opened the same file in Kwrite, it is just a simple acii text file, selected the printer and checked that paper source should be Tray 1, but no Tray2 supplies the sheet.
Note:Reading the manual and searching the net, there appears to be a difference between the settings that the CUPS driver can perform and the actual settings available when using the Printer Display Panel (or via the embedded webserver) with nothing to loose I have found the following settings to work for me:
Tray 1 Papersize = ANY
Tray 1 Media = ANY
Tray 2 Papersize = A4
Tray 2 Media = Plain
Tray 1 is "single sheet feed" sometimes open and when open will take precedence over Tray 2. Mostly closed and only opened to feed a few sheets manually for whatever reason.
Tray 2 is the 250 sheet feeder, normally used and is filled with Plain A4 size paper
The system now works as I wished it to, but will not work if Tray one is set to Size=A4, Media=Plain which I considered natural as I generally only use A4 plain paper.
Further using 'normal' ie. not postscript drivers seem to loose a number of capabilities. I think I have confirmed that the recommended CUPS PostScript driver for this printer can not be fully configured from CUPS default settings or command line input. I would like to look a bit closer at that but now that I have the configuration I wished for I think I may leave it as is.
The two identical ppd PostScript Level 2 files are not particularly CUPS made, they are just ppd and there is a funny not that indicates it is made for Macintosh only?? A curiosity but HP recommends this for use in PCLOS HPLIP and I think this is fine.
I should not forget trying to run the tray selection via CUPS command line either, think I have seen something in lpoptions. From above this could be tricky and depend on if Printer Panel settings are already in your favour.
I should check out the Foomatic ppd Postscript version just to complete the PostScript section. A quick look confirmed that the size of this file was not likely to support the full range of Default settings from CGI (CUPS Grahics Interface) management. For example "Media" can not be set and doing it as command line interface there appear no easy way to see if it had any effect
Grrrrrrrr
