04-03-2020 09:07 PM
Topology: RID:
C1 - C2 0.0.0.1 - 0.0.0.2
| / \ | | /\ |
W1 W2 0.0.0.11 0.0.0.22
| |
BGP EIGRP
C1 is always selecting W2 as the border router for every route, even if W2 has not any route learnt:
C1:
i 0.0.0.2 [2] via 172.16.1.6, Ethernet1/2, ASBR, Area 0, SPF 26
i 0.0.0.11 [102] via 172.16.1.6, Ethernet1/2, ASBR, Area 0, SPF 26
i 0.0.0.22 [1] via 172.16.1.6, Ethernet1/2, ASBR, Area 0, SPF 26
Interface PID Area AF Cost State Nbrs F/C
Et1/2 100 0 ipv4 1 P2P 1/1
Et1/1.780 100 0 ipv4 1000 P2P 1/1
Et0/0 100 0 ipv4 10 P2P 1/1
C2:
i 0.0.0.1 [10] via 172.16.1.1, Ethernet0/0, ASBR, Area 0, SPF 27
i 0.0.0.11 [100] via 172.16.1.14, Ethernet1/1, ASBR, Area 0, SPF 27
i 0.0.0.22 [1] via 172.16.1.18, Ethernet1/2.780, ASBR, Area 0, SPF 27
Interface PID Area AF Cost State Nbrs F/C
Et1/2.780 100 0 ipv4 1 P2P 1/1
Et1/1 100 0 ipv4 100 P2P 1/1
Et0/0 100 0 ipv4 10 P2P 1/1
W1:
i 0.0.0.2 [1] via 172.16.1.13, GigabitEthernet2/0, ASBR, Area 0, SPF 21
i 0.0.0.1 [10] via 172.16.1.9, GigabitEthernet0/0.780, ASBR, Area 0, SPF 21
i 0.0.0.22 [2] via 172.16.1.13, GigabitEthernet2/0, ASBR, Area 0, SPF 21
Interface PID Area AF Cost State Nbrs F/C
Gi2/0 100 0 IPv4 1 P2P 1/1
Gi0/0.780 100 0 IPv4 10 P2P 1/1
W2:
i 0.0.0.1 [10] via 172.16.1.5, GigabitEthernet2/0, ASBR, Area 0, SPF 19
i 0.0.0.2 [1] via 172.16.1.17, GigabitEthernet0/0.780, ASBR, Area 0, SPF 19
i 0.0.0.11 [101] via 172.16.1.17, GigabitEthernet0/0.780, ASBR, Area 0, SPF 19
Interface PID Area AF Cost State Nbrs F/C
Gi0/0.780 100 0 IPv4 1 P2P 1/1
Gi2/0 100 0 IPv4 10 P2P 1/1
C1 is the only one not respecting the topology, so when routes are lost from W2, C1 still selects W2 creating a black hole:
Routing entry for 192.168.200.0/24
Known via "ospfv3 100", distance 110, metric 200
Tag 1480, type extern 2, forward metric 102
Last update from 172.16.1.6 on Ethernet1/2, 00:21:34 ago <-- IP of W2
Routing Descriptor Blocks:
* 172.16.1.6, from 0.0.0.11, 00:21:34 ago, via Ethernet1/2 <-- RID is from W1 but IP and IF is towards W2
Route metric is 200, traffic share count is 1
Route tag 1480
04-04-2020 02:11 AM
Hi,
Can you post a diagram with how are the routers physically connected and also how the print are formed? An output of "show ip ospf neighbors" would help as well as "show ip ospf database external x.x.x.x" from both the ASBR's and a regular router.
Regards,
Cristian Matei.
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