ospf database issue

Unanswered Question
Nov 19th, 2008

Hi Guys

I have run into a problem which i just dont understand.

If i perform a show ip route i can see a route learnt via ospf in the routing table

cisco#sho ip route 10.231.27.254

Routing entry for 10.231.27.0/24

Known via "ospf 100", distance 110, metric 13001, type intra area

Last update from 172.31.38.12 on Tunnel10, 00:09:58 ago

Routing Descriptor Blocks:

* 172.31.38.12, from 172.31.39.7, 00:09:58 ago, via Tunnel10

Route metric is 13001, traffic share count is 1

But if i search the ospf database for it i cant locate it..

cisco#sho ip ospf database | i 10.231

cisco#

Could someone explain exactly what is occuring? I suspect im missing something obvious.

Thanks

Andre

I have this problem too.
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Harold Ritter Wed, 11/19/2008 - 06:02

Andre,

The command "show ip ospf database" only shows an LSA summary of the OSPF database. 10.231.27.0/24 is an an intra-area route so would be derive from the information in the LSA type 1 and type 2. Try "show ip ospf data" and "show ip ospf net" to find the information about this subnet.

Regards

Harold Ritter Wed, 11/19/2008 - 12:53

Andre,

Sorry. I meant "show ip ospf da router" and "show ip ospf data net".

Regards

Giuseppe Larosa Wed, 11/19/2008 - 06:02

Hello Andre,

this is an intra area route so the subnet 10.231.27.0 can be part of a router LSA that has a tag = OSPF router-id

try

sh ip ospf database adv-router 172.31.38.12 [detail]

Hope to help

Giuseppe

andretimoll Wed, 11/19/2008 - 06:30

Hi Giuseppe

If I try that command I still can't see that route in the database, i haven't got the option for detail.

Am I not right in assuming theses intra area routes must be in the database to be installed in the routing table?

cisco#sh ip ospf database adv-router 172.31.38.12 ?

| Output modifiers

OSPF Router with ID (172.31.39.233) (Process ID 100)

Router Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Link count

172.31.38.12 172.31.38.12 280 0x800180E9 0x001704 42

Summary Net Link States (Area 1)

Link ID ADV Router Age Seq# Checksum

10.252.1.0 172.31.38.12 783 0x8000065B 0x000FC5

10.252.2.0 172.31.38.12 783 0x8000065B 0x0004CF

10.252.3.0 172.31.38.12 783 0x8000065B 0x00F8D9

10.252.4.0 172.31.38.12 784 0x8000065B 0x00EDE3

10.252.5.0 172.31.38.12 784 0x8000065B 0x00E2ED

10.252.6.0 172.31.38.12 784 0x8000065B 0x00D7F7

10.252.7.0 172.31.38.12 784 0x8000065B 0x00CC02

10.252.8.0 172.31.38.12 784 0x8000065B 0x00C10C

10.252.9.0 172.31.38.12 784 0x8000065B 0x00B616

10.252.10.0 172.31.38.12 784 0x8000065B 0x00AB20

10.252.254.0 172.31.38.12 783 0x800044F8 0x002853

172.31.38.1 172.31.38.12 784 0x80001022 0x00E434

172.31.38.2 172.31.38.12 784 0x8000065B 0x008662

172.31.38.16 172.31.38.12 784 0x8000065B 0x00F9E6

172.31.38.74 172.31.38.12 784 0x80004F3D 0x000A6C

172.31.38.75 172.31.38.12 784 0x8000065B 0x00A9F5

Summary ASB Link States (Area 1)

Link ID ADV Router Age Seq# Checksum

172.31.38.1 172.31.38.12 783 0x80001022 0x00CC4C

172.31.38.2 172.31.38.12 784 0x8000065B 0x006E7A

The subnet I am trying to get to should be a network LSA as it is the LAN subnet on another router in area 1. The network setup is all the remote sites are in area 1 which is connected to area 0. Could this setup be the reason why the ospf database looks incomplete??

Giuseppe Larosa Wed, 11/19/2008 - 07:07

Hello Andre,

the net you are looking for is inside the router LSA data structure

Router Link States (Area 1)

Link ID ADV Router Age Seq# Checksum Link count

172.31.38.12 172.31.38.12 280 0x800180E9 0x001704 >>>>42

the link count is 42 so you can understand that here multiple links, and multiple ip subnets are contained.

try

sh ip ospf database router 172.31.38.12

the net is clearly in the database but it can be difficult to find it because a single router lsa exist for each OSPF node.

if the net is associated to a broadcast segment the DR router will generate a Network LSA.

From your output we can understand that router 172.31.38.12 is not the DR for the enquired subnet.

As suggested by Harold you can also use

sh ip ospf database network

this should return some info

Hope to help

Giuseppe

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