OSPF external route cant be installed in routing table

[Majid Jalinousi]

Hi buddies,

I've an issue with OSPF external routes and I cant understand why the routes cant be installed on the routing table.

The topology of the network is like below:

R1(10.1.1.2) -> (10.1.1.2)R2(10.1.2.2) -> (10.1.2.3)R3

So a OSPF routing protocol between R1 and R2 is running and they are neighbors on the area 0. between R2 and R3 there is no OSPF neighbor-ship but OSPF is enabled on the interface connected to R3 and R2 will learn all the subnets behind R3 through static route and redistribute them on the OSPF domain.

On R1 I have OSPF external routes for subnets redistributed to OSPF domain with forward address of 10.1.2.3. Although I have an intra ospf route for this forward address on the routing table of R1, the external routes redistributed on to the OSPF with this forward address cant be installed on the routing table of R1. what would be prevent for installing these external routes?

I would be so appreciate for any help.

BR.

[Georg Pauwen]

Hello,

post the full configs of all three routers.

[Majid Jalinousi]

So apalogize for that, but because of some security issues I'm unathorized for posting the configs.

Just I want to know what made this situation be happened? Then an external route couldn't install in the routing table.

By the way by making interface connected to R3 passive interface, the route could install in the routing table.

Thanks advance.

[Julio E. Moisa]

Hi

Have you verified if there is a route-map with prefixes or tags into the redistribution? Please correct me but you want to redistribute the static routes on R2 into OSPF, right? 

[Majid Jalinousi]

Hello, thanks for your reply

Yes, I want to redistribute static routes on to the OSPF, for that I used the command "redistribute static subnets route-map Redist" and any subnets that I want to redistribute on OSPF, just match them on the route-map. Also there is no tagging for these subnets and route-map just Includes a match command. 

Thanks

BR. 

[paul driver]

hello 

why do you have OSPF enabled on the r3 when no adjacency is allowed?

as for rtr2 not redistributing it’s static are they being matched within the route-map you’ve are specifiying for the statics ?

res

paul

[Majid Jalinousi]

Thanks Paul, 

Right's with you, it's not needed to enable ospf on the R2 interface toward R3 and as I said before making this interface passive solved the problem.

When I did the command "show ip ospf database external x.x.x.x"at R1 I could see the redistributing route but the routing bit was not set and the route couldn't be installed on the routing table and the forwarding address was 10.1.2.3.

When I did checked the routing table for 10.1.2.3 I found it as a intra area route and according about this situation the redistributing routes don't have any reason for not installing in the routing table

If I not correct, please inform me? 

BR. 

[paul driver]

Hello

---

@Majid Jalinousi wrote:

Thanks Paul, 

Right's with you, it's not needed to enable ospf on the R2 interface toward R3 and as I said before making this interface passive solved the problem.

When I did the command "show ip ospf database external x.x.x.x"at R1 I could see the redistributing route but the routing bit was not set and the route couldn't be installed on the routing table and the forwarding address was 10.1.2.3.

When I did checked the routing table for 10.1.2.3 I found it as a intra area route and according about this situation the redistributing routes don't have any reason for not installing in the routing table

If I not correct, please inform me? 

BR. 

---

FYI - I was on about R3 interface having opsf applied.

As for R2 - I would say it is needed so the network between R2-R3 can be advertised into ospf towards R1for the return path between R1-R3 - That said it can be passive as no adjacency is required.

res
Paul

[Julio E. Moisa]

Hi

Static routing will not be redistributed if you are not using a Tag as identifier, o you can redistribute using: redistribute static subnet, only, or matching acl/PL with the specific subnet mask. 

So with tagging it should be like:

ip route 1.1.1.1 255.255.255.255 2.2.2.2 tag 100

route-map STATIC-TO-OSPF permit 5

match tag 100

router ospf 1

redistribute static route-map STATIC-TO-OSPF subnet

Hope it is useful

:-)

[Majid Jalinousi]

For redistributing a station route we did like below:

IP access-list standard 10

Permit 1.1.1.1 0.0.0.0

Route-map Redist permit

Match ip address 10

Router ospf 100

Redistribute static subnets route-map Redist

Actually it works and at R1 ospf database we have all the redistribution routes.

But thew can't be installed on the routing table. 

[Julio E. Moisa]

Hi, that config is fine, are using the matched subnet mask or using VRFs? or try cleaning the entry into the routing table: clear ip route 1.1.1.1

[Majid Jalinousi]

Thanks again, 

There is no vrf, and for matched subnet mask you mean the format of matched access-list? Yes we use wildcard for matching the subnets

And about clear ip route, no I didn't use that, after making the interface between R2-R3 passive everything was OK.

The difference after making that interface passive was the forward address became all zero and the routes installed in the routing table. 

I can't understand that.

BR. 

[paul driver]

Hello Julio
Can you elaborate in this please - not sure I understand?

If I am correct this topology-rtr1/2 are the only rtrs with OSPF adjacency and due to their redistribution both are asbr’s with rtr2/3 having a static and default routing between each other

So Rtr1/trt2 should be able to redistribute without any tag value providing reach ability between Rtr1/3

Res
Paul

[Julio E. Moisa]

Hi,

Yes, it could be redistributed without tag, the configuration is ok and it should be work, I think there are no VRFs, problably restarting the router could work. No area types or it is displayed on the OSPF database?

[paul driver]

Hello Julio
Apologies then I thought I had Mis read your post mate nw -