extern void free_subnet_tree(avl_tree_t *);
extern void subnet_add(struct node_t *, subnet_t *);
extern void subnet_del(struct node_t *, subnet_t *);
extern void free_subnet_tree(avl_tree_t *);
extern void subnet_add(struct node_t *, subnet_t *);
extern void subnet_del(struct node_t *, subnet_t *);