Virtual IP (VIP) Multiport Services
A single VIP can support custom services with multiple port entries by creating multiple service entries under that VIP -- one service entry in the VIP for ewach port entry in the service. By default, you can use single-port services in a VIP.
To be able to use multiple-port services in a VIP, you must first issue the CLI command:
...and then reset the device.(Taken from the
ScreenOS-5.3.0.pdf file.)
However, it looks like the Netscreen 25 has a limit of 64 total ports which can be assigned to a VIP. This means you cannot assign large-port-count services (like Netbackup) to a VIP, you have to burn a mapped IP (MIP).