07-09-2021 10:08 AM - edited 07-11-2021 09:27 AM
Hello,
I'm having a bit of a trouble trying to configure an OSPF setup here on packet tracer. You can find my topology in the attachement Capture.PNG.
What's happening is that my "BERLIN" labelled router just doesn't get any of the routes it's supposed to via OSPF :
Router#show ip route
!!!snip!!!
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
C 10.10.6.0/24 is directly connected, GigabitEthernet0/1
L 10.10.6.254/32 is directly connected, GigabitEthernet0/1
C 10.10.100.0/28 is directly connected, GigabitEthernet0/0
L 10.10.100.6/32 is directly connected, GigabitEthernet0/0
The wierd part is that i constantly get logging messages on this router, like so :
00:23:55: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
00:24:05: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
00:24:15: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
00:24:25: %OSPF-5-ADJCHG: Process 10, Nbr 1.1.1.1 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
00:24:35: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
00:24:45: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
00:24:50: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
00:24:55: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on GigabitEthernet0/0 from LOADING to FULL, Loading Done
It's just alternating between 2.2.2.2 ( MADRID ) and 1.1.1.1 ( LISBOA )
Although my configuration seems fine :
BERLIN'S CONFIGURATION :
Current configuration : 770 bytes
!
version 15.1
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
!
!
no ip cef
no ipv6 cef
!
!
!
!
license udi pid CISCO1941/K9 sn FTX15244MM2
!
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 10.10.100.6 255.255.255.240
duplex auto
speed auto
!
interface GigabitEthernet0/1
ip address 10.10.6.254 255.255.255.0
duplex auto
speed auto
!
interface Vlan1
no ip address
shutdown
!
router ospf 10
router-id 6.6.6.6
log-adjacency-changes
network 10.10.6.0 0.0.0.255 area 0
network 10.10.100.0 0.0.0.15 area 0
!
ip classless
!
ip flow-export version 9
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
login
!
!
!
end
Here's LISBOA'S configuration, which seems to be chosent as DR.
Current configuration : 994 bytes
!
version 15.1
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
!
!
no ip cef
no ipv6 cef
!
!
!
!
license udi pid CISCO1941/K9 sn FTX152425E6
!
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 10.10.1.254 255.255.255.0
duplex auto
speed auto
!
interface GigabitEthernet0/1
ip address 10.10.100.2 255.255.255.240
duplex auto
speed auto
!
interface Serial0/0/0
ip address 10.10.100.17 255.255.255.252
!
interface Serial0/0/1
ip address 10.10.100.21 255.255.255.252
clock rate 2000000
!
interface Vlan1
no ip address
shutdown
!
router ospf 10
router-id 1.1.1.1
log-adjacency-changes
network 10.10.1.0 0.0.0.255 area 0
network 10.10.100.16 0.0.0.3 area 0
network 10.10.100.20 0.0.0.3 area 0
network 10.10.100.0 0.0.0.15 area 0
!
ip classless
!
ip flow-export version 9
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
login
!
!
!
end
Finally, MADRID :
Router#show run
Building configuration...
Current configuration : 977 bytes
!
version 15.1
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
!
!
no ip cef
no ipv6 cef
!
!
!
!
license udi pid CISCO1941/K9 sn FTX1524DL27
!
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
!
!
interface GigabitEthernet0/0
ip address 10.10.100.2 255.255.255.240
duplex auto
speed auto
!
interface GigabitEthernet0/1
ip address 10.10.2.254 255.255.255.0
duplex auto
speed auto
!
interface Serial0/0/0
ip address 10.10.100.18 255.255.255.252
clock rate 2000000
!
interface Serial0/0/1
ip address 10.10.100.25 255.255.255.252
clock rate 2000000
!
interface Vlan1
no ip address
shutdown
!
router ospf 10
router-id 2.2.2.2
log-adjacency-changes
network 10.10.2.0 0.0.0.255 area 0
network 10.10.100.16 0.0.0.3 area 0
network 10.10.100.0 0.0.0.15 area 0
!
ip classless
!
ip flow-export version 9
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
login
!
!
!
end
Thanks for your help !
Solved! Go to Solution.
07-11-2021 09:42 AM
now I see two 10.10.100.2 ip, please can correct it and check again.
07-10-2021 03:47 AM - edited 07-10-2021 03:51 AM
can I see show ip interface brief for Berlin branch ?
I see double IP address 10.10.100.6 config in to two routers this is issue I think, please change one of them.
07-11-2021 09:28 AM
My mistake, i pasted twice the same configuration when I created the post. Now it's edited. Here is the IP interface brief for Berlin :
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0 10.10.100.6 YES manual up up
GigabitEthernet0/1 10.10.6.254 YES manual up up
Vlan1 unassigned YES unset administratively down down
Thanks for your help
07-11-2021 09:42 AM
now I see two 10.10.100.2 ip, please can correct it and check again.
07-11-2021 10:57 AM
Oh my god... I can't believe i banged my head against the wall for two days because of a simple ip address duplicate... Thanks for your response anyway.
Conclusion : weird loops like this may be caused by two routers having the same IP address on the same subnetwork. Hope it can help someone to know this
07-11-2021 11:02 AM
You are So So Welcome
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