What is the flow of traffic in a Spine/Leaf network?

Traffic flow in a Spine/Leaf network flows from the host connected to the Leaf to the Spine, eventually to the destination Leaf and the awaiting host. Leaf switches are connected only to the Spine; therefore, traffic cannot flow from the host to a Leaf to another Leaf directly. Hosts should not be connected to Spine switches, so traffic will not flow from the host to the Spine to a Leaf and then a Spine switch.