How To Create a Virtual Link Extension (VLE)

A Virtual Link Extension (VLE) is a logical link or tunnel.  A VLE connect ports within a switch, or from a port on one switch to a port on a switch in another cluster. This feature provides a mechanism for link state tracking between two ports of two switches in the same fabric for VLE.

The VLE feature requires that a Layer-3 fabric must be deployed from an UNUM Layer-3 Playbook. For more information on creating a Layer-3 Fabric please refer to Manager Fabric for more information.

UNUM provides a "pick and choose" itemized list of VLE settings for easy configuration.

The workflow in building a VLE involves four basic steps:


Configuration Note: Whenever possible, physically cabling the devices to be connected to their respective ports before creating the VLE simplifies the process.


  1. Use one of two methods to create a Virtual Link Extension:
    1. From the Overlay ring graphic in the dashboard hold the Control or Command key on your keyboard and click on two switches represented by colored arcs in the ring. The VLE Connection dashboard opens and you enter the desired configuration parameters.
    2. Use  (Manager → Services → VLE → Manage VLE) to create a VLE. To add a VLE click Create Virtual Link Extension. The VLE Connection dashboard opens and you enter the desired configuration parameters. In either case:
    • Provide a meaningful name, such as Leaf1p30-L3p30, where the VLE will connect Leaf1, Port 30 to Leaf3, Port30.
    • When creating the VLE, each requires a unique vlan and vxlan identifier, e.g. VLAN 30, VXLAN 10030.
  1. Verify the port state is up via the Port Status dashboard (Manager → Layer 1 → PHYSICAL PORTS → Port Status).
  2. Complete the connection between devices by cabling both ends of the VLE to their respective devices (unless this was already done).
  3. Trigger a VLE discovery from the VLE Overlay (Overlay → Overlay details → Gear button → Trigger VLE discovery).


At this point the VLE inter-link connection in the ring diagram updates reflecting the new VLE connection. Changes in the inter-link visual indicators from Green to Red, or vice versa, indicate whether ports are "up" or "down".

In either case, the VLE is created and displayed in the dashboard. Bringing the ports "up" and ensuring the Tunnel is "up" changes the VLE status to Up.


If the inter-link connection stays Red, please verify that the port(s) state is up and the respective devices are connected and active.

Interactively Manage VLE via the Dashboard

As shown in the following example, you click on a switch (LEAF113) which highlights. While holding the Control or Command key on your keyboard select a second switch (LEAF133). The VLE Connection dashboard opens and you enter the desired configuration parameters.

Click Submit to continue or Cancel to return to the previous screen without making any changes.

Overlay Dashboard - Interactive VLE Manage

Virtual Link Extension - Example

In summary, UNUM provides a convenient method for configuring your switches with VLEs.