Information about FabricPath in Transit Mode
In transit mode, all the incoming traffic is mapped to one internal bridge domain (VLAN). A pure Layer 2 spine node does not learn the MAC addresses; however, the packet is VDC based on the VDC ID lookup table in the FabricPath header.
In a FabricPath network, the Layer 2 spine node can be configured in Transit mode. After the spine is configured in the Transit mode, uni-destination traffic received on the spine is forwarded based on the FTAG (forwarding tag) and destination VDC ID. For multi-destination traffic, the traffic on the spine is forwarded based on FTAG, which is the identifier of the multi-destination traffic that is selected by the ingress switch.