OSPF mismatch area ID

[D T]

Hi,

My router generate an ospf invalid packet, ( Router A and B are generating these log ).

%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from x.x.x.x  (router C IP address) vlan xx

show ip ospf interface on each directly connected interface ( A to ABR and c to ABR ) resulting a same ospf area,

Any suggestion or advise why these log shows up? i don't use virtual links and as far as i know there's no routing issue / problem happen.

[Peter Paluch]

Hello Daniel,

This looks as if you assigned the links from A to ABR and from B to ABR to the area 1 only in the A/B configuration, but on ABR routers, these links are still assigned to area 0. Please verify that using the command

show ip ospf interface brief

on both ABRs - watch for the Area column in the output. Both ABRs must report the links to A and B being also placed into area 1.

Best regards,

Peter

[D T]

Hi Peter,

thanks for your reply, i've verified both links from router a/b to ABR and ABR to a/b is on the same area,

here is the output

ROUTER A

router-A#sh ip ospf int b

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

Vl232        1     12             10.204.14.34/30    10    BDR   1/1

ROUTER B

router-B#sh ip ospf int b

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

Vl332        1     12             10.204.15.34/30    10    BDR   1/1

ABR A

ABR-A#sh ip ospf int vl232

Vlan232 is up, line protocol is up

  Internet Address 10.204.14.33/30, Area 12

ABR B

ABR-B#sh ip ospf int vl 332

Vlan332 is up, line protocol is up

  Internet Address 10.204.15.33/30, Area 12

[Peter Paluch]

Daniel,

Thank you for keeping me informed.

This is interesting. Note that the ABRs appear to have a successful peerings with A and B according to the F/C column. The show ip ospf neighbor on router A and B should hence confirm a successful adjacency of A and B to ABRs.

I had a closer look at the message you provided:

%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone  area must be virtual-link but not found from x.x.x.x  (router C IP  address) vlan xx

This is interesting. Routers A and B can see OSPF Hello packets from router C. This looks like the ABRs are actually switching the packets from C to A and B, or somehow, the OSPF Hello packets from router C are leaking to A and B. Do you have a common VLAN that spans from A/B through ABRs to C? That would explain this phenomenon.

Best regards,

Peter

[D T]

Hi Peter,

Just to make things more clear, These is the logs i've seen on router A and B

%OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from 10.204.34.17, Vlan111

I did some checking whether vlan 111 also span to C

router-A#  sh ip ospf int br

Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

Vl232        1     12             10.204.14.34/30    10    BDR   1/1

Vl111        1     12             10.204.1.8/24      400   DR    1/1

router-A#sh vlan id 111

VLAN Name                             Status    Ports

---- -------------------------------- --------- -------------------------------

111  VLAN0111                         active    Gi0/1, Gi0/2, Gi0/3, Gi0/4, Gi0/5, Gi0/8, Gi0/12

router-C# sh vlan id 111

VLAN 111 not found in current VLAN database

vlan 111 is not spanned to router C , but i find it on router-ABR-A

router-ABR-A#sh vlan id 111

VLAN Name                             Status    Ports

---- -------------------------------- --------- -------------------------------

111  VLAN0111                         active    Po17

router-ABR-A#sh cdp ne po17 d

-------------------------

Device ID: *****************

Entry address(es):

  IP address: 10.204.40.242

router-ABR-A#sh run | b er os

router ospf 1

router-id 10.204.12.91

log-adjacency-changes

auto-cost reference-bandwidth 10000

network 10.204.40.240 0.0.0.7 area 0

ABR-A assigned vlan 111 to area 0,  is this what causing the logs on router A,B ?

[Peter Paluch]

Hello,

I am somewhat at loss seeing the diverse router ID's without knowing what exactly they refer to, but according to what you have commented, it seems that both router A and ABR-A have interface Vlan111 configured, and while A has this interface put into area 12, ABR-A has this interface in area 0, resulting in area mismatch.

However, if I am to believe that the error message displayed on A refers to the IP address of C, not ABR-A, as you originally indicated, then it still must be the Vlan111 being simply trunked over ABR-A towards switch C.

Seeing your logical topology, i.e. what VLANs exist and how the routers are interconnected by them, would be helpful.

Best regards,

Peter

[Alexander Maroukian]

Entry address(es):

  IP address: 10.204.40.242

router-ABR-A#sh run | b er os

router ospf 1

router-id 10.204.12.91

log-adjacency-changes

auto-cost reference-bandwidth 10000

network 10.204.40.240 0.0.0.7 area 0

ABR-A assigned vlan 111 to area 0,  is this what causing the logs on router A,B ?

Hi,

If this network(10.204.40.240 0.0.0.7) is not in area 0, this could cause the problem. But this router C address in the error message is a bit strange.

Regards,

Alex

[boss.silva]

Hello,

Would you mind posting the sanitized config of all the switches/routers involved?

Regards,

Bruno Silva.