V_linux_eth_unr
clear_unrhdr(V_linux_eth_unr);
delete_unrhdr(V_linux_eth_unr);
ifp->if_linux_ethno = alloc_unr(V_linux_eth_unr);
free_unr(V_linux_eth_unr, ifp->if_linux_ethno);
V_linux_eth_unr = new_unrhdr(0, INT_MAX, NULL);