Hi Thierry,

Thanks for the packet logs - they were very interesting!  It looks to me
as if CUPS is continually trying to talk to your print server using
IPP/2.0, which it does not appear to support.  With the present code,
CUPS expects it to return an error of IPP_VERSION_NOT_SUPPORTED, which
is used as a hint to downgrade the connection.  In practice, your server
acts in a similar way to Web servers, and returns a response as IPP/1.0.

Would you mind applying the following inline patch to the existing
version from comment #12 and seeing if that helps?

=== modified file 'backend/ipp.c'
--- old/backend/ipp.c   2011-10-28 09:12:41 +0000
+++ new/backend/ipp.c   2011-10-29 00:11:43 +0000
@@ -247,6 +247,7 @@
   ppd_file_t   *ppd;                   /* PPD file */
   _ppd_cache_t *pc;                    /* PPD cache and mapping data */
   fd_set       input;                  /* Input set for select() */
+  int server_ipp_version;
 
 
  /*
@@ -830,6 +831,18 @@
 
     supported  = cupsDoRequest(http, request, resource);
     ipp_status = cupsLastError();
+    
+    /* Extract server IPP version, and use this to downgrade */
+    server_ipp_version = supported->request.any.version[0]*10;
+    server_ipp_version += supported->request.any.version[1];
+    if (version > server_ipp_version)
+    {
+      fprintf(stderr, "INFO: Server responded to our IPP/%d.%d request ", 
+              version / 10, version % 10);
+      fprintf(stderr, "with an IPP/%d.%d response - downgrading!\n",
+              server_ipp_version / 10, server_ipp_version % 10);
+      version = server_ipp_version;
+    }
 
     fprintf(stderr, "DEBUG: Get-Printer-Attributes: %s (%s)\n",
             ippErrorString(ipp_status), cupsLastErrorString());


** Patch added: "Full patch for CUPS 1.5.0 with auto-downgrade (untested) + 
missing-document-type fixes"
   
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/881843/+attachment/2577307/+files/ipp-patch2-all.patch

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https://bugs.launchpad.net/bugs/881843

Title:
  CUPS IPP print to Novell servers error since 11.10 upgrade

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