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OSPF Route Missing

Our company are running OSPF over Cisco routers with 4 areas - 0, 2, 3 and 4.

0 is the core area linking the others together.

For end sites we don't put OSPF on as there's only 1 possible route out so we just add a default route and redistribute the site's network range from statics added to the core site's router.

We have recently added a new site to area 4 and have therefore added a new static route which is being redistributed into OSPF on the core router that the new site links back into. This is working fine and all areas picked up the new network as expected, execept for one particular 3640 core router in area 0. I've checked this router and all the OSPF is configured correctly as far as I can see(timers, key etc.) and all the neighbors are present. This router sees all the OSPF area routes and redistributed routes fine including all other static routes redistributed from the same core router that the new site links back to. However, it just won't add this one network into it's database! Does anyone know what steps I can take to troubleshoot why this one router is having this problem or has anyone experienced something similar before?

Many thanks, Paul

2 REPLIES

Re: OSPF Route Missing

Hello,

first I would check, if the LSA5 (and LSA4 announcing the ASBR) are present in the OSPF database on the 3640 in question. It would be helpfull to get the output from "show ip ospf databse external" and "show ip ospf database asbr-summary" regarding the ASBR and network in question of the 3640 and one other router, where it works.

Regards, Martin

Cisco Employee

Re: OSPF Route Missing

I would first look at the specific lsa type 5 "show ip ospf data ext x.x.x.x" from the 3640. Check to see whether there is a "forward address". Then do a "show ip route x.x.x.x" for the forward address and make sure that it is learnt via OSPF. OSPF will not install a external route in the RIB if the forward address is not learnt via OSPF.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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