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New Member

Route not showing up in OSPF database

I've included a diagram outlining the scenario I'm dealing with. I have a site, Site A which is a 'hub' site connecting to two other sites, each with their own OSPF processes. I'm currently using redistribution to redistribute desired routes from A to B, B to A, A to C, C to A. Inclusive in that are routes that originate in C traverse through A and make it to B. My problem is I have one route w.x.y.z/16 that does not make it into the OSPF database for Process B for site B from C, where another route a.b.c.d/16 sourced from C as well does make it into the database and is then injected into the routing table for site B. I have confirmed that my ACLs used for redistribution are correct, in fact the ACLs show matches for both routes mentioned above, however w.x.y.z/16 never makes it into the database. I've been unable to find any doc, or a good reason for the difference in the handling of the two routes. Any suggestions would be helpful.

Thank you

Mike

I have an issue where some routes from one region are being

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: Route not showing up in OSPF database

In addition you may find the following useful, if you haven't see already. Not directly related to your problem, but gives some good tips when dealing with red between ospf processes.

http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080531fd2.shtml

18 REPLIES
New Member

Re: Route not showing up in OSPF database

Here is the diagram for the above message.

Thanks

Mike

Hall of Fame Super Gold

Re: Route not showing up in OSPF database

Mike

I do not believe that there is enough information here to understand what is causing the problem. If you can provide the appropriate parts of the router config we might be able to help you find the cause of the problem.

HTH

Rick

New Member

Re: Route not showing up in OSPF database

Also can you explain the rationale behind multiple ospf processes?

Is this a test set-up or a production network?

Are there any other redistribution points on your network (not shown in the diagram)?

Rgds

E.

New Member

Re: Route not showing up in OSPF database

Hi, to answer both of your questions I have include the router configs from Site A and Site C, OSPF Process C was set up in Site A and C to act as a transit area. Site B's OSPF process extends to Site A so there is no specific configuration. You are correct, both site B and C have connections to another router, call it A1. The configuration on A1 is the same as A (included). Both A1 and A do not have network w.x.y.z in their databases. Since two routers in Site A connect to each of Site B and C we using route tagging to ensure we don't receive routes from B or C that we distributed into their environments.

Sites B and C were brought into the fold afterwards, each having their own OSPF processes. Demarcation was required between OSPF processes.

Thanks

Mike

New Member

Re: Route not showing up in OSPF database

Attachments ...again ....

New Member

Re: Route not showing up in OSPF database

Sorry..bad day ....

New Member

Re: Route not showing up in OSPF database

Hi Mike,

I will spend a bit of time looking at the configs. Meanwhile here is something for you to think about. Please correct me if I'm wrong, but I suspect you have used multiple ospf processes to be able do do route filtering. Are you aware of ABR Type-3 LSA filtering. I have used it and works very well.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a00800b5d4f.html

It may be the way forward (if indeed you have done it for filtering) as I believe in the future you will probably keep running into problems with this approach.

Rgds

E.

Purple

Re: Route not showing up in OSPF database

Hi Mike,

Does the route w.x.y.z appear in A's routing table ?

Paresh

New Member

Re: Route not showing up in OSPF database

Yes, it definitely does appear in A's routing table. This is part of my problem. It seems to me that all the criteria have been met to allow the route to be redistributed.

ekiriakos, thank you for the suggestion. I'll definitely take it under consideration. I thank you both for taking the time to look at this.

Regards

Purple

Re: Route not showing up in OSPF database

Hi,

Can you try the following on router A:

router ospf A

redistribute ospf C metric-type 1 subnets route-map C_to_A match internal external

Paresh

New Member

Re: Route not showing up in OSPF database

Thanks Paresh, I will give this a try, though itseems to me the addition of the match internal/external will be redundant given that the ACL stipulates the networks to match already. One question though, if site A has redistributed a route to site C as an E1 route, if I use the match external will it then redistributed back to me since it will match any E1 route it seeing that process? That is why I had set up tagging in the first place so we don't get routes back that had just redistributed to the other process.

An important piece of information I have discovered is that historically the network was matched in the ACL, however I have removed and readded the permit statement for the network and the router will not match it anymore (something has changed that is not allowing the ACL to match the network that it once did). Still investigating that.

New Member

Re: Route not showing up in OSPF database

Hi Mike,

Can I clarify one poin. Do you have multiple redistribution points? In other words is router A the only router doing red for this subnet or others as well?

Rgds

E.

New Member

Re: Route not showing up in OSPF database

I do have multiple redistribution points (please see updated diagram). Right now Sites D (same configuration as A) sees route a.b.c.d from its virtual access 2 interface (multilink ppp) with a metric of x. Site A sees the same route with a metrix of x+10. a.b.c.d originating from Site D, by the time it reaches Site A has a metric of x+5 thus Site A uses that route vs the route it learned from its virtual access interface. Thus the network gets redistributed from C to A to B.

For network w.x.y.z both site A and D see the route with a metric of y. Consequently they trust their own network as it will be the lower cost metric. Because of this they do not see the network originate from a neighbour they do not redistribute the network into Process B. Thus the network gets redistributed from C to A but not to B.

I think this is the problem/solution. As mentioned above the Type 3 LSA configuration is probably the way to go, but for now I may just redistribute from C to B in the same fashion as above. I was coming to this conclusion today, please let me know if it seems reasonable.

New Member

Re: Route not showing up in OSPF database

Let me make sure I understand this. The linkes between B-D and B-A are in area-B. The links between D-C and A-C are in area C. Is this correct?

Area-A exists on routers D and A to be used for redistributing between area-B and area-C ?

Also is there a link between D-A? If yes what area is it in?

New Member

Re: Route not showing up in OSPF database

Your analysis is correct. The area A exists for the link between D and A. Further to my analysis yesterday since route metrics necessitate the use of the locally learned route in Site A and D (via virtual access 2) which is Area C the route will not be redistributed from A to B since the route does not exist in area A. I'm 99% confident that that is the issue. Would you agree?

I apologize if not providing all of the information upfront has caused some confusion.

Mike

New Member

Re: Route not showing up in OSPF database

I agree. On the same router when redistributing from protocol X to -> Y and then from Y to -> Z, then X will NOT be redistributed into Z.

Rgds

E.

New Member

Re: Route not showing up in OSPF database

In addition you may find the following useful, if you haven't see already. Not directly related to your problem, but gives some good tips when dealing with red between ospf processes.

http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080531fd2.shtml

New Member

Re: Route not showing up in OSPF database

Thank you everyone for your help, redistribution from C to B solved the problem. I will be reviewing the links provided in order to optimize the way I redistribute routes.

Mike

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