The end-host mode is the default mode of operation for UCS Fabric Interconnect Ethernet connectivity. In this mode, UCS Fabric Interconnect is presented to the northbound LAN switch as an end host with many adapters. STP is not configured on the uplink switch ports. Since there is no STP, all FI ports are in the forwarding state irrespective of the northbound topology. This means that data traffic can use any of the FI uplink ports/port channels. In this mode, Fabric Interconnect is in the active/active usage state.

The data traffic flow is accomplished through the pinning of host interfaces to the Fabric Interconnect uplink ports. Host interface pinning can be configured dynamically or statically. All Fabric Interconnect uplink ports are configured as 802.1q trunks. No control protocol is used on the uplinks. MAC Address learning only happens for southbound server ports and not on uplink ports:

In order to configure or verify EHM for Fabric Interconnects, follow these steps:

1. Log into UCS Manager.
2. Click on the Equipment tab in the navigation pane.
3. On the Equipment tab, click on Fabric Interconnect A (as shown in the following screenshot).
4. The Status area in the work pane shows the current Ethernet Mode configuration which is End Host.

5. In the Actions area of the work pane, the currently configured Ethernet Mode, which in this case is End Host, will be shown grayed:

A Fabric Interconnect reboot is required in order to change the Ethernet Mode from End Host to Switch and vice versa.

In order to change the Ethernet Mode from End Host to Switch, perform the following steps:

1. Log into UCS Manager.
2. Click on the Equipment tab in the navigation pane.
3. In the Equipment tab, click on Fabric Interconnect A (as shown in the following screenshot).
4. In the Actions area of the work pane, the currently configured Ethernet Mode, which in this case is End Host, will be shown grayed and cannot be selected.
5. Click on Set Ethernet Switching Mode in the Actions area of the work pane.
6. Click on Yes on the pop-up warning message to restart Fabric Interconnect:

7. After Fabric Interconnect restarts, the Ethernet Mode is changed to Switch.