JunOS : Cannot have the same local address on different units of an interface

By | January 3, 2014

Getting this error doing a commit after assigning a subnet to a L3-interface vlan on your Juniper device?

user@EX4200# set interfaces vlan unit 100 family inet address 1.1.1.1/8

user@EX4200# commit synchronize comment “add subnet to vlan 100”
[edit protocols]
‘bgp’
[edit protocols]
‘ospf3’
[edit interfaces vlan unit 100 family inet]
‘address 1.1.1.1/8’
Cannot have the same local address on different units of an interface
error: configuration check-out failed
{master:0}[edit]

Let’s see what we possibly have already configured with subnet 1.1.1.1/8 :

Well, we clearly see that subnet 1.1.1.1/8 is already assigned to vlan 10. You need to remove the statement that assign that subnet from the wrong vlan before commit again :

Then commit the change :