This read-only value is the incoming-direction counterpart to lportOutVAvailbwQoS1, reporting how much inbound virtual bandwidth remains available within the QoS Class 1 reservation on this port. An admin checks this specifically for asymmetric traffic scenarios, since ATM QoS reservations and thus available headroom can differ between the outgoing and incoming directions on the same port. For example, a port might have plenty of available outgoing class-1 bandwidth but very little available incoming class-1 bandwidth if most existing voice circuits on that port are receiving rather than sending heavily, a distinction only visible by checking this incoming counter separately.