Current design never deletes faces but only mark them as deleted. This is designed to prevent creation and deletion at high rate when ifaces are used for few interests. The current design implement a counter in each face/iface, when it is set to 0 the face/iface is mark as deleted but never deallocated. On ifaces, each counter means that there is at least one interest pending in the pit that must be satisfied by the corresponding data. If we deallocate every time the counter reaches 0 we might allocate and deallocate faces at high rate (allocation and reallocation requires adjusting an hash table, which means that a lookup must be performed). A better approach might implement a process node that periodically scan the list of faces and ifaces and deallocate them.