If you have configured a Virtual Local Area Network (VLAN) on an interface and try to bind multiple IP addresses to the same VLAN, an error message is displayed when binding the IP addresses that are members of the same subnet.

The following is a sample command sequence that attempts to bind multiple IP addresses to the same VLAN:

add vlan 30
bind vlan 30 -ifnum 1/1
bind vlan 30 -IPAddress 10.1.10.200 255.255.255.0
bind vlan 30 -IPaddress 10.1.10.21 255.255.255.0
ERROR: Operation not permitted
bind vlan 30 -IPaddress 10.1.10.22 255.255.255.0
ERROR: Operation not permitted

In the preceding set of commands, notice that an error message is displayed when you attempt to bind the last two IP addresses to the interface.

Run the following commands to bind IP addresses that belong to a different subnet not the same subnet.

As follows, bind 10.1.20.21 255.255.255.0 to vlan 30, as it belongs to a different subnet. 
NS> bind vlan 30 -IPaddress 10.1.20.21 255.255.255.0
Done
NS>

Show vlan command confirms the preceding configuration:
NS> sh vlan
VLAN ID: 30 VLAN Alias Name:
Interfaces : 1/1

The following IPs are used:
10.1.10.200 Mask: 255.255.255.0
10.1.20.21 Mask: 255.255.255.0

Problem Cause

When you bind an IP address to a dedicated VLAN on an interface, all the IP addresses defined in the subnet to which the bound IP address belongs are automatically bound to the interface. Therefore, when you attempt to bind another IP address of the same subnet, an error message is displayed.

10.1.10.21,10.1.10.22 and 10.1.10.200 have a subnet mask 255.255.255.0 that are members of same subnet. So, after we bind 10.1.10.200 to the vlan 30 and interface 1/1, all other IP for example, 10.1.10.21 and 10.1.10.22 are automatically bound to the same interface. Therefore, attempt to bind these displays the error.