Configure a Sub-Interface

Let us learn to configure a sub-interface.
You can create sub-interfaces on physical or virtual interfaces and use bypass pairs for Local Area Networks (LANs) and private and public Wide Area Networks (WANs). A sub-interface is created by dividing one physical interface into multiple virtual interfaces.
The parent interface can be an Ethernet port, a virtual port, or a bypass pair that does not contain any configuration. You cannot configure a sub-interface on the controller port or any interfaces or bypass pairs already configured with loopback as a member with PPPoE or standard VPNs.
  • If the sub-interface is on a bypass pair and the sub-interface is used for internet or private WAN, then the sub-interface is created on the bypass pair's WAN port.
  • If the sub-interface is on a bypass pair and the sub-interface is used for LAN, then the sub-interface is created on the LAN port of the bypass pair.
Multiple sub-interfaces may be configured on a physical or virtual interface or bypass pairs. If multiple interfaces are configured, a VLAN ID is required to create and uniquely identify each sub-interface.
device releases, LAN sub-interfaces may only be used for the following branch services.
Release 5.1.1 and later
device releases enable LAN sub-interfaces to forward user and application traffic in addition to the following branch services.
  • DHCP Server
  • DHCP Relay
  • DHCP Relay source interface
  • SNMP Agent
  • SNMP Trap source interface
  • Ping to and from the interface IP
  • Secure Socket Shell (SSH) access to the ION device CLI commands
You cannot configure a Virtual Interface (VI) on a sub-interface. DHCP Relay and DHCP server cannot be configured on the same sub-interface. DHCP Relay when configured on a sub-interface:
  • Can listen to broadcast and unicast DHCP requests.
  • Can use the sub-interface as the source interface to reach DHCP servers.
When SNMP is configured on a sub-interface:
  • An SNMP Agent can listen to unicast requests.
  • An SNMP Trap can use the sub-interface as the source interface to reach SNMP servers.
  1. From
    Claimed Devices
    , select a device and click
    Configure the device
  2. Select the
  3. Select a port.
  4. For
    Admin Up
    , select
  5. (Optional)
    Enter a
  6. Leave
    Use This Port To
  7. Save Port
  8. Click the
  9. Select
    + Add Sub-Interface
    to create a new sub-interface.
  10. For
    Admin Up
    , select
  11. (Optional)
    Enter a
  12. From
    Use This Sub-Interface To
    drop-down, select the option applicable to the interface you are configuring;
    Connect to Internet
    , or
    Peer with a Network
  13. For
    Circuit Label
    , select circuits and click
  14. Enter a
    The VLAN ID can be updated or changed.
  15. Mark the Native VLAN box if the identified sub-interface is used for native VLAN.
    Only one sub-interface of a parent interface can be configured for native VLAN. By default, the native VLAN box is unchecked.
    DNS Servers need to be entered for Internet and Private WAN but not for LAN.
  16. (Optional)
    If DHCP Relay functions are required, choose
    for the
    field. Change
    Add DHCP Relay
  17. Select
    Create Sub-Interface

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