[cups.bugs] Socket backend communication problem Kyocera IB-20IB-21 network cards

[Michael Sweet]

William Crowell wrote:
> CUPS 1.2.6
> GLIBC 2.4, 2.5
> GCC 4.1.1
> Kernel 2.6.18.2
> (Gentoo Base)
> All Kyocera printers using IB-20/IB-21 network adapters with socket connection 
> to 9100.
> 
> First print job will process most of the time. Subsequent print jobs produce 
> no output. Something in the socket communication is causing the Kyocera cards 
> to hang. Power-cycling the printer will reset for the next job.

The socket backend does the following:

     1. Create a socket
     2. Connect the socket to the printer
     3. Write the print data to the printer and read any backchannel
        data from the printer
     4. Shutdown the outgoing side of the socket
     5. Wait for the printer to close the connection, reading any
        backchannel data from the printer while it waits
     6. Close the socket

You can look at the code if you like, but it can't get any simpler
than that.  Either the Kyocera print servers are broken or the Linux
TCP/IP stack is broken.  My money is on the Kyocera print servers.

You can try using the "waiteof=no" option to see if the Kyocera
doesn't like the shutdown stuff (step 4 above):

     socket://ipaddress/?waiteof=no

however, that would just indicate that the printer does not implement
the TCP/IP spec properly and you need to get a firmware updated from
Kyocera that fixes the bug.

> *This is not a problem with running multiple copies of a single job.*
> 
> /var/log/cups/error_log shows messages about "discarded events" from the 
> socket backend.

That's the notification stuff, and they aren't coming from the socket
backend, but from the scheduler which sends event notifications for
changes to the job or printer, as appropriate...

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Document Software          http://www.easysw.com