Re: OSPF neighbor down, yet OSPF database is not

From: Fahad Khan (fahad.khan@gmail.com)
Date: Thu Aug 21 2008 - 08:30:31 ART

For how long you found this behaviour? I mean to say that, may be after a
certain period of time,you saw them out of database table. Database table
contains LSAs only, may be this has some thing to do with LSA aging time.

On 8/21/08, Geert Nijs <Geert.Nijs@simac.be> wrote:
>
> 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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-- 
*FAHAD KHAN

BE Computer Systems NED,

CCNA,CCDA,CCNP,FOUNDFE,CLSE,QOS,JNCIA,JNCIS,MCP,CCIE  (Written)

Systems Support Engineer, Premier Systems (Pvt) limited,

Karachi, Pakistan

92-321-2370510.*

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