Hi, *Issue Description*: LSA ID collision issue is seen with OSPF *stub-networks* configured and BIRD is acting as ABR *BIRD OSPF configuration*: · Part of 2 areas (say, area-0 and area-100) · Stub-networks are configured in area-0 *Code Flow*: 1. Stubnets are advertised to area-0 by generating router LSA ( LSA_T_RT). o ospf_disp() -> ospf_update_topology() -> ospf_originate_rt_lsa()->ospf_ originate_lsa() 2. Now, stubnets are added to top graph table (p->gr) with LSA type LSA_T_RT 3. When creating routing table, these stubnets are added to FIB ( p->rtf). o ospf_disp() -> ospf_rt_spf() -> ospf_rt_spfa() -> spfa_process_rt() -> add_network() -> ri_install_net() 4. When BIRD is acting as ABR then, walk through FIB(p->rtf) and send summary LSA (LSA_T_SUM_NET) with LSA mode as LSA_M_RTCALC. Also, nf pointer is set (stores fib node address) in top_hash_entry. o ospf_disp() -> ospf_rt_abr2() -> check_sum_net_lsa() -> ospf_originate_sum_net_lsa() ->ospf_originate_lsa() 5. Now, stubnets are added to top graph table (p->gr) with LSA type LSA_T_SUM_NET 6. Stubnets are removed from FIB(p->rtf) o ospf_disp() -> rt_sync() -> fib_delete() 7. Now, stubnets entries are still present in top graph table (Note: fib_delte() doesn't free the node, it just moves the fib node to free pool, fib_node pointer is still valid) 8. With any change in network, ospf_rt_spf()is called. In ospf_rt_reset(), LSA mode is updated fromLSA_M_RTCALC to LSA_M_STALE. 9. Again, steps 3-6 are repeated. In step-3, fib node pointer is changed and in step-4, fib node pointer comparison fails in ospf_originate_lsa()which is leading to LSA id collision. *Issue is resolved with below code change. *Please review the change and provide your comments. Also, please let me know if any other information is required. diff -rupN bird/proto/ospf/topology.c bird_modified/proto/ospf/topology.c --- bird/proto/ospf/topology.c 2016-11-28 05:14:19.582761752 -0800 +++ bird_modified/proto/ospf/topology.c 2016-11-28 05:14:01.270761752 -0800 @@ -278,7 +278,7 @@ ospf_originate_lsa(struct ospf_proto *p, if (!SNODE_VALID(en)) s_add_tail(&p->lsal, SNODE en); - if (!en->nf || !en->lsa_body) + if (!en->nf || !en->lsa_body || en->mode == LSA_M_STALE) en->nf = lsa->nf; Thanks, Naveen