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underlying-interface (demux0)


Hierarchy Level


Configure the underlying interface on which the demultiplexing (demux) interface is running.


Before you make any changes to the underlying interface for a demux0 interface, you must ensure that no subscribers are currently present on that underlying interface. If any subscribers are present, you must remove them before you make changes.


underlying-interface-name—Either the specific name of the interface on which the DHCP discover packet arrives or one of the following interface variables:

  • $junos-underlying-interface when configuring dynamic IP demux interfaces.

  • $junos-interface-ifd-name when configuring dynamic VLAN demux interfaces.

The variable is used to specify the underlying interface when a new demux interface is dynamically created. The variable is dynamically replaced with the underlying interface that DHCP supplies when the subscriber logs in.


Logical demux interfaces are currently supported on Gigabit Ethernet, Fast Ethernet, 10-Gigabit Ethernet, or aggregated Ethernet interfaces.

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 9.3.

Support for aggregated Ethernet introduced in Junos OS Release 9.4.