This read-write value sets/reports the interface ID at the egress port of the destination node for this leaf, applicable if this is a PVC, meaning it identifies the specific interface on the far-end (destination) node where this leaf's traffic ultimately exits toward its endpoint device. Being read-write (unlike most other leaf topology fields, which are read-only) it can be explicitly provisioned for statically configured PVC leaves rather than only being discovered dynamically. An engineer manually provisioning a new leaf onto an existing multipoint PVC tree would set cktLeafDestIfIndex to the specific port on the destination switch where the new remote endpoint's circuit terminates.