FabricPath is designed to interoperate with other Layer 2 technologies such as vPC. vPC+ provides extensions to vPC for connecting classical Ethernet devices to a FabricPath cloud. vPC+ enables the entire vPC domain to be seen as one virtual switch by the FabricPath network. vPC+ enables classical Ethernet devices such as hosts or STP domains to communicate with each other through the cloud. With vPC+, the FabricPath cloud is seen as a single L2 bridge for STP purposes. In other words you can say – A virtual port channel+ (vPC+) domain allows a classical Ethernet (CE) vPC domain and a Cisco FabricPath cloud to interoperate. a vPC+ also provides a First Hop Routing Protocol (FHRP) active-active capability at the FabricPath to Layer 3 boundary.
vPC+ can also enables FabricPath nodes to combine as a single virtual switch for the purpose of creating active/active First Hop Redundancy Protocols (FHRPs) such as HSRP and GLBP to operate in an active/active fashion.
Few points worth remembering regarding vPC+
- The vPC Peer-Link and all vPC members must reside on F1, F2, or F2e linecards.
- Peer-Switch is not recommended in a vPC+ domain configuration.
- The vPC+ should be configured with STP priorities low enough to ensure that they become the root bridge of the connected L2 domain.
Also I had found a video from INE, which explains functioning and configuration of vPC+ in a very lucid way -
For more information on vPC+ click here