Particular port configurations may allow invalid printers to be built on Mac OS X via Bonjour.
By default ExtremeZ-IP will accept inbound print jobs on port 515. This can be changed in the ExtremeZ-IP Administrator via the Print Server Settings tab in the Settings dialog box. Changing this setting can break some Bonjour printers.
Under Mac OS X Panther (10.3.X) or earlier, print jobs are sent to port 515 regardless of the port specified by the server when the printer is built. Printers built under Mac OS X Tiger (10.4.X) or using the Windows Bonjour client will send jobs to the port specified by the server when the printer is built.
Keep in mind that changing any printer port configuration may break previously built printers.