Disabling a Physical Interface
You can disable a physical interface, marking it as being down, without removing the interface configuration statements from the configuration. To do this, include the disable statement at the [edit interfaces interface-name] hierarchy level:
 | Caution: Dynamic subscribers and logical interfaces use physical interfaces for connection to the network. The Junos OS allows you to set the interface to disable and commit the change while dynamic subscribers and logical interfaces are still active. This action results in the loss of all subscriber connections on the interface. Use care when disabling interfaces. |
 | Note: On the router, when you use the disable statement at the edit interfaces hierarchy level, depending on the PIC type, the interface might or might not turn off the laser. Older PIC transceivers do not support turning off the laser, but newer Gigabit Ethernet PICs with SFP and XFP transceivers do support it and the laser will be turned off when the interface is disabled. |
 | Warning: Do not stare into the laser beam or view it directly with optical instruments even if the interface has been disabled. |
Example: Disabling a Physical Interface
Disable a physical interface:
