dn_tag_get
ip = (struct ip *)mtodo(m, dn_tag_get(m)->iphdr_off);
ip = (struct ip *)mtodo(m, dn_tag_get(m)->iphdr_off);
ip = (struct ip *)mtodo(m, dn_tag_get(m)->iphdr_off);
pkt = dn_tag_get(m);
struct dn_pkt_tag *dt = dn_tag_get(m);
dn_tag_get(m)->output_time = V_dn_cfg.curr_time + s->link.delay ;
dn_tag_get(m)->output_time += t;
struct dn_pkt_tag *pkt = dn_tag_get(m);
struct dn_pkt_tag * dn_tag_get(struct mbuf *m);