Interfaces Stack Higher Layer

1.3.6.1.2.1.31.1.2.1.1

The value of ifIndex corresponding to the higher sub-layer of the relationship, i.e., the sub-layer which runs on 'top' of the sub-layer identified by the corresponding instance of ifStackLowerLayer. If there is no higher sub-layer (below the internetwork layer), then this object has the value 0.