ospf database entries not appearing

Unanswered Question
Sep 27th, 2008

I have a problem where a route entry is not appearing in the ospf database. My understanding was that the database would populated with all entries to a particular destination and would then install the preffered route into the routing table.

I have a problem at the moment where the ospf database is not being populated with all possible entries.

Is there an easy way to troubleshoot this issue by running some ospf debug commands?

I have attached some sh commands, the entry in question is the 10.9.0.0/16, I see 2 entries but I should see a 3rd via 1.1.1.1 which I currently don't.

Can anyone help?

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Giuseppe Larosa Sat, 09/27/2008 - 03:17

Hello Darran,

I would investigate on why the LSA type 5 from negighbor with RID 1.1.1.1 is missing for net 10.9.0.0/16.

What kind of area is the vlan412 where the neighbor 1.1.1.1 is seen ?

post

sh ip ospf interface vlan412

on router with RID 1.1.1.1 what commands are present in the router ospf process ?

does it look like :

router ospf 61

summary-address 10.9.0.0 255.255.0.0

the router with RID 1.1.1.1 has a route to 10.9.0.0/16 or at least a route to one subnet of 10.9.0.0/16 that is learned via a static or bgp or other routing protocol ?

Hope to help

Giuseppe

wave-stream Tue, 09/30/2008 - 04:26

Hi Giuseppe,

The ospf area for vlan 412 is just a standard ospf area (area 60).

The router 1.1.1.1 learns the 10.9.0.0/16 route from another ospf process and is redistributed into the ospf 61 process connecting to vlan 412, there is no summary of this on this router, that is the route it learns, this route would originally come from bgp then into ospf

Jon

Harold Ritter Tue, 09/30/2008 - 05:30

Jon,

Did you configure the keyword "subnet" when you redistribute from one ospf process to the other.

Regards

wave-stream Tue, 09/30/2008 - 05:42

Hello, yes this is configured. If I look at the routing table for 1.1.1.1, I see the route for 10.9.0.0 but the entry does not appear in the databse of the opsf neighbors.

Its a bit of a strange problem, where I have 3 possible paths of reaching the 10.9.0.0/16 network, but I only ever seem to get either 1 of the 3 entries or 2 of the 3 entries in the database.

I'm wondering if this is a bug, but I'm not ure the best way to debug.

Do you know of a debug command that I can run to see if the l3 device is receiving an lsa from 1.1.1.1 for the 10.9.x.x subnet?

Harold Ritter Tue, 09/30/2008 - 06:16

Jon,

The issue is that for route the route to be redistributed from one OSPF process to the other, this route needs to be installed in the RIB on the redistributing router.

Check on the neighbor with RID 1.1.1.1 and will you most likely find out that the route installed in the RIB is actually coming from the router with RID 10.236.32.4.

Regards

wave-stream Tue, 09/30/2008 - 06:37

Hello,

This is the information I see on 1.1.1.1

OSPF Instance 62

Area 0.0.0.60 LSDB

Type Link ID ADV Router Age Seq# Checksum

1 2.2.2.8 2.2.2.8 1280 0x8000010c 0x7657

1 1.1.1.2 1.1.1.2 498 0x800009a4 0xa39c

2 10.236.32.9 1.1.1.2 498 0x80000101 0x31e2

Type Link ID ADV Router Age Seq# Checksum

5 10.9.0.0 2.2.2.8 1280 0x80000069 0xe59a

OSPF Instance 61

Area 0.0.0.60 LSDB

Type Link ID ADV Router Age Seq# Checksum

1 10.236.32.2 10.236.32.2 1298 0x800020b6 0x5da3

1 10.236.32.3 10.236.32.3 1836 0x80000b04 0x1ed3

1 10.236.32.4 10.236.32.4 1634 0x800008bb 0x8aa6

1 10.236.32.6 10.236.32.6 1844 0x80000025 0x5c14

1 10.236.32.5 10.236.32.5 558 0x80000026 0xb7c1

1 10.236.32.1 10.236.32.1 922 0x80002b72 0xb998

1 1.1.1.1 1.1.1.1 498 0x80000f78 0x292

2 10.236.32.18 10.236.32.2 534 0x80000c9d 0x37e9

2 10.236.32.30 10.236.32.4 372 0x8000005b 0x1f3e

2 10.236.32.106 10.236.32.3 1836 0x80000022 0xf84e

2 10.236.32.26 10.236.32.6 1844 0x80000022 0xa6ee

2 10.236.32.22 10.236.32.5 307 0x80000059 0xce96

2 10.236.32.99 10.236.32.2 534 0x80000989 0x7270

AS External LSDB

Type Link ID ADV Router Age Seq# Checksum

5 10.9.0.0 10.236.32.6 193 0x80000020 0x41eb

5 10.9.0.0 10.236.32.5 1931 0x80000020 0x524

This router redistributes from ospf 62 to 61 and from 61 to 62, it learns the route 10.9.0.0 on both sides, but the preffered route is via 10.236.32.5 and 10.236.32.6

so would I epxect to see 3 entries in my 10.236.32.4 device

1 from 1.1.1.1

2 from 10.236.32.5

3 from 10.236.32.6

is this correct?

Harold Ritter Tue, 09/30/2008 - 06:48

Jon,

No, you shouldn't expect to see 3 LSAs on 10.236.32.4. The situation is exactly as I was pointing out.

On router 1.1.1.1, the external LSA from process 61 is installed in the RIB, which prevents the external LSA from process 60 to be installed in the RIB and therefore to be redistributed in process 61. This is the drawback of having separate process and doing redistribution between them.

Regards

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