net_protocol_register
ipst->ips_ipv4_net_data = net_protocol_register(id, &ipv4info);
ipst->ips_ipv6_net_data = net_protocol_register(id, &ipv6info);
ipst->ips_arp_net_data = net_protocol_register(id, &arp_netinfo);
extern net_handle_t net_protocol_register(netid_t, const net_protocol_t *);
if ((vnh->vnh_neti = net_protocol_register(nid, netip)) == NULL) {