OSPF neighbor down, yet OSPF database is not updated/refreshed

From: Geert Nijs (Geert.Nijs@simac.be)
Date: Thu Aug 21 2008 - 08:21:55 ART


Hi all,

I have strange stuff going on in my network. Yesterday, i bounced an interface (shut/no shut) to reset an OSPF neighborship.
However, when the neighbor was down, it seemed OSPF didn't update its database. The routes were still in the OSPF database. I don't understand:
The routes concerned are external redistributed routes:

show ip ospf database

               Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
10.50.0.0 19.16.139.113 1421 0x800001EE 0x00E290 401 <<<------------ look at these routes
10.50.0.0 19.16.139.114 1040 0x8000004D 0x001B2D 400
10.50.32.0 19.16.139.113 1421 0x800001EE 0x0081D1 401 <<<------------ look at thse routes
10.50.32.0 19.16.139.114 1040 0x8000004D 0x00B96E 400

sh ip ospf neighbor
19.16.139.113 1 FULL/BDR 00:00:19 10.63.14.1 Vlan997

Then i disable the interface:
%OSPF-5-ADJCHG: Process 1, Nbr 19.16.139.113 on Vlan997 from FULL to DOWN, Neighbor Down: Dead timer expired

sh ip ospf database
10.50.0.0 19.16.139.113 1725 0x800001EE 0x00E290 401 <<<-- STILL HERE ???
10.50.0.0 19.16.139.114 1344 0x8000004D 0x001B2D 400
10.50.32.0 19.16.139.113 1725 0x800001EE 0x0081D1 401 <<<-- STILL HERE ???
10.50.32.0 19.16.139.114 1344 0x8000004D 0x00B96E 400

ping 19.16.139.113
..... <<-- he is down for sure

Why doesn't the database get updated ? I need the route to be removed and re-inserted/refreshed with an up-to-date tag.

regards,
Geert
CCIE #13729

Details when neighbor is UP:

# sh ip ospf database external 10.50.0.0
       OSPF Router with ID (192.168.1.1) (Process ID 1)

                Type-5 AS External Link States
  LS age: 1897
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 10.50.0.0 (External Network Number )
  Advertising Router: 19.16.139.113 <---- this is it
  LS Seq Number: 800001EE
  Checksum: 0xE290
  Length: 36
  Network Mask: /19
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 60
        Forward Address: 0.0.0.0
        External Route Tag: 401

  Routing Bit Set on this LSA <--- what does this mean ? this is the redundant path route and currently the preferred one. Is there no refresh when "routing bit" not set ?
  LS age: 1516
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 10.50.0.0 (External Network Number )
  Advertising Router: 19.16.139.114 <---redundant path, currently selected (see cost)
  LS Seq Number: 8000004D
  Checksum: 0x1B2D
  Length: 36
  Network Mask: /19
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 10
        Forward Address: 0.0.0.0
        External Route Tag: 400 <<<--- i want this tag to update !!

Details when neighbor is DOWN:

# sh ip ospf database external 10.50.0.0
       OSPF Router with ID (192.168.1.1) (Process ID 1)

                Type-5 AS External Link States
  LS age: 1984
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 10.50.0.0 (External Network Number )
  Advertising Router: 19.16.139.113 <-------- STILL HERE !
  LS Seq Number: 800001EE
  Checksum: 0xE290
  Length: 36
  Network Mask: /19
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 60
        Forward Address: 0.0.0.0
        External Route Tag: 401

  Routing Bit Set on this LSA
  LS age: 1603
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 10.50.0.0 (External Network Number )
  Advertising Router: 19.16.139.114
  LS Seq Number: 8000004D
  Checksum: 0x1B2D
  Length: 36
  Network Mask: /19
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 10
        Forward Address: 0.0.0.0
        External Route Tag: 400

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