Server Spools Jobs Endlessly if AppleTalk Print Device Removed

• Microsoft Windows NT Server version 3.5

SYMPTOMS

If a Windows NT 3.5 print server running Services for Macintosh captures an AppleTalk print device in its zone whose name in Print Manager is the same as the print device name, the following problems will occur whenever the print server loses its connection to the print device:

• On the Windows NT print server, the printer will send new print jobs to itself, rather than to the print device, in an endless loop.
• If the print device later becomes available, the Windows NT print server will not recapture it.

CAUSE

When a Windows NT print server captures an AppleTalk print device, it creates a network connection to that print device. Once the connection is established, the print device stops advertising its name on the zone, and the Windows NT print server starts using the print device's name for the print server's print share name.

If the print server loses its connection to the print device, the print server issues an AppleTalk NBPLookup() call, using the print device's original name, in an attempt to reestablish the connection. Because the Windows NT print server is advertising its print share under that name, and the real AppleTalk print device is not available on the network, the Windows NT print server responds to its own NBPLookup(). At this point, the server establishes a connection to what it believes to be the print device, but what is really the server's print share. Instead of sending new jobs to the print device, the print server starts sending job to itself in an endless loop.

If the original AppleTalk print device again becomes available on the network, the scenario described above does not change. The AppleTalk print device looks for it's original name on the zone and finds the Windows NT print server already using that name. To avoid a name conflict, the print device creates a new name for itself by appending a number to the end of its original name, incrementing the number until the name is unique. Because the print server looks for the device under its original name, it will never find the print device.

This problem does not occur in native Macintosh networks, because AppleShare print servers clear AppleTalk printer names whenever they lose their connections. The AppleShare solution is not an option in Windows NT 3.5, because of the more flexible printing architecture provided by Windows NT. Windows NT lets network clients send print jobs even if the print device is not immediately available. The AppleShare solution would prohibit this functionality. Also, Windows NT can create printer pools in which jobs sent to one print share are distributed over several print devices. The AppleShare solution would require removing a shared printer pool from the network whenever one device in the pool became unavailable.

RESOLUTION

To avoid these problems, do either of the following before you capture an AppleTalk print device in Print Manager:

• Make the Windows NT printer name different from the AppleTalk print device name.
• Put the AppleTalk print device and the Windows NT server in different AppleTalk zones.

STATUS

Microsoft has confirmed this to be a problem in Windows NT Server version 3.5. This problem was corrected in Windows NT version 3.51.