Also:

Plumbing and unpluming is when IP is "connected" to DLPI - connecting the plumbing as it were. This "connecting" is binding the IP and ARP SAPs to the NIC so the driver will start passing IP and ARP packets up to IP and (surprise) ARP.

Once an interface is plumbed, you can assign IP addresses to it. On HP-UX, the first "ifconfig lanN" does an implicit plumb operation so it is uncommon to acctually issue a "plumb" directly. Also, on HP-UX, an unplumb will do an implicit deleting of IP addresses. (IIRC)

Excellent!

By using plumb you can create a virtual network interface in your server,Using unplumb you can remove the same.

Virtual interfaces allow a single ethernet interface to listen on additional IP addresses.

This command will use if you don't have multilple network interface in your server.This command will help you mainly in  testing enviornments.


Following are steps to configure the Virtual interface using plumb.

 An ethernet interface "hme0" (use ifconfig -a to identify the names of your interfaces), you can create a subinterface called hme0:1 with the following command:

1. (a) ifconfig hme0:1 plumb  
    (b) ifconfig hme0:2 plumb  

 You can set the IP address of the interface to 192.168.1.10 and turn on the interface with the following command
 
2.  (a) ifconfig hme0:1 192.168.1.10 up
     (b) ifconfig hme0:2 192.168.1.11 up

To make the virtual interface persist when you  reboot, you can add the ip address or hostame from /etc/hosts in the file /etc/hostname.hme0:1


Note :- All of the subinterfaces on a physical interface need to be in the same subnet.

Thanks
RK