ciscoAtmVclCrossVpi 1.3.6.1.4.1.9.10.13.1.2.1.1.16

This specifies the VPI value of the VCL to which this VCL is cross-connected. For point to multi-point connection, this is the root VCL's VPI for the leaf entry. Similarly it is the 1st leaf's VPI value for the root entry.