I have a setup as in the attached drawing. I can see that the bird ABR node (R2) sets the E-bit and the B-bit in the router LSA. The B-bit seems correct as it is the ABR, but it is not an ASBR. Below is a tcpdump captured on R1 Frame 11347: 124 bytes on wire (992 bits), 124 bytes captured (992 bits) Linux cooked capture v2 PPP-over-Ethernet Session Point-to-Point Protocol Internet Protocol Version 4, Src: 10.210.138.69, Dst: 224.0.0.5 Open Shortest Path First OSPF Header Version: 2 Message Type: LS Update (4) Packet Length: 76 Source OSPF Router: 10.210.138.69 Area ID: 0.0.0.0 (Backbone) Checksum: 0x9d61 [correct] Auth Type: Null (0) Auth Data (none): 0000000000000000 LS Update Packet Number of LSAs: 1 LSA-type 1 (Router-LSA), len 48 .000 0000 0000 0001 = LS Age (seconds): 1 0... .... .... .... = Do Not Age Flag: 0 Options: 0x42, O, (E) External Routing 0... .... = DN: Not set .1.. .... = O: Set ..0. .... = (DC) Demand Circuits: Not supported ...0 .... = (L) LLS Data block: Not Present .... 0... = (N) NSSA: Not supported .... .0.. = (MC) Multicast: Not capable .... ..1. = (E) External Routing: Capable .... ...0 = (MT) Multi-Topology Routing: No LS Type: Router-LSA (1) Link State ID: 10.210.138.69 Advertising Router: 10.210.138.69 Sequence Number: 0x80000075 Checksum: 0x180f Length: 48 Flags: 0x03, (E) AS boundary router, (B) Area border router 0... .... = (H) flag: No ...0 .... = (N) flag: No .... 0... = (W) Wild-card multicast receiver: No .... .0.. = (V) Virtual link endpoint: No .... ..1. = (E) AS boundary router: Yes .... ...1 = (B) Area border router: Yes Number of Links: 2 Type: Stub ID: 10.210.138.69 Data: 255.255.255.255 Metric: 0 Type: PTP ID: 10.210.138.66 Data: 10.210.138.69 Metric: 10 The Cisco router sees these bird routers as ASBR routers as well R3-Cisco>show ip ospf border-routers OSPF Router with ID (10.210.138.65) (Process ID 1) Base Topology (MTID 0) Internal Router Routing Table Codes: i - Intra-area route, I - Inter-area route i 10.210.138.66 [1] via 10.210.138.66, GigabitEthernet0/0/1, ASBR, Area 0.0.0.0, SPF 77 i 10.210.138.69 [11] via 10.210.138.66, GigabitEthernet0/0/1, ABR/ASBR, Area 0.0.0.0, SPF 77 I 10.210.138.73 [21] via 10.210.138.66, GigabitEthernet0/0/1, ASBR, Area 0.0.0.0, SPF 77 R3-Cisco> R3-Cisco>show ip ospf database OSPF Router with ID (10.210.138.65) (Process ID 1) Router Link States (Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum Link count 10.210.138.65 10.210.138.65 870 0x800000DE 0x0091B0 2 10.210.138.66 10.210.138.66 828 0x800000AC 0x00DBB2 3 10.210.138.69 10.210.138.69 828 0x8000009F 0x00C339 2 Net Link States (Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum 10.210.138.65 10.210.138.65 870 0x80000035 0x003F26 Summary Net Link States (Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum 10.210.138.73 10.210.138.69 591 0x8000002D 0x002465 Summary ASB Link States (Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum 10.210.138.73 10.210.138.69 591 0x8000002D 0x001672 Type-5 AS External Link States Link ID ADV Router Age Seq# Checksum Tag 0.0.0.0 10.210.138.65 1650 0x80000034 0x004EA1 1 R3-Cisco>
