NETWORK_LVL
inp->igm_level = NETWORK_LVL;
inp->igm_level = NETWORK_LVL;
isp->input[NETWORK_LVL] = ipv4_input;
isp->output[NETWORK_LVL] = ipv4_output;
isp->close[NETWORK_LVL] = NULL;
isp->headerlen[NETWORK_LVL] = ipv4_header_len;
if (igp->igm_level != NETWORK_LVL) {
if (ogp->igm_level != NETWORK_LVL) {
ogp->igm_level = NETWORK_LVL;
(sockets[i].headerlen[NETWORK_LVL])(NULL);
oc.igm_level = NETWORK_LVL;