HPMON Stops Working After Upgrading Multiple-NIC Computers

• Microsoft Windows NT operating system version 3.1
• Microsoft Windows NT Advanced Server version 3.1
• Microsoft Windows NT Workstation version 3.5
• Microsoft Windows NT Server version 3.5

SYMPTOMS

When you reinstall or upgrade Windows NT on a computer with multiple network interface cards (NICs), the HPMON print monitor cannot send print jobs to previously defined network printers.

CAUSE

This happens because HPMON identifies your computer's NICs by number, and the installation or upgrade process can change these numbers.

When you install, reinstall, or upgrade Windows NT, a number is assigned to each NIC in your computer. The one with the lowest I/O base address is assigned the number 0, the one with the next lowest I/O base address is assigned the number 1, and so on. However, if you later add a new NIC to the system, it is assigned the next unused numbers, regardless of its I/O base addresses. Then, when you reinstall or upgrade, the numbering is reassigned by I/O base address.

As an example, say you install Windows NT on a computer with two adapters, NIC-A and NIC-B, with I/O base addresses of 368h and 360h, respectively. NIC-B becomes adapter 0, and NIC-A becomes adapter 1. If you later install another adapter, NIC-C, with I/O base address 358h, it becomes adapter 2. Then you reinstall or upgrade Windows NT and the adapter numbers are reassigned. NIC-C becomes adapter 0, NIC-B becomes adapter 1, and NIC-A becomes adapter 2.

There is no way for Setup to identify services that rely on NIC numbering. These services cannot automatically adjust to the reassigned numbers and do not function correctly after an upgrade or reinstall.

The HPMON print monitor relies on the DLC protocol to send print jobs to network printers equipped with HP JetDirect adapters. DLC may be bound to multiple NICs, but HPMON only uses one of the DLC-bound NICs. It stores that NIC's number in the registry, in the HKEY_LOCAL_MACHINE subtree in this key:

   \SYSTEM
     \CurrentControlSet
       \Control
         \Print
           \Monitors
             \Hewlett-Packard Network Port
               \Options
                 \Adapter

WORKAROUND

There are two ways to work around this problem:

• If the computer has only two adapters, then you can reconfigure HPMON through Print Manager. Choose Properties from the Printer menu, then choose the Settings button, then the Options button, and change the Adapter value from Primary to Secondary, or from Secondary to Primary.
• If the computer has more than two adapters, you can manually alter the registry value mentioned above. Change the value to the adapter number of the correct network adapter card.

  WARNING: Using the Registry Editor incorrectly can cause serious, system- wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of the Registry Editor can be solved. Use this tool at your own risk.