Redistribution between Static Network and OSPF Network

[Abdul Mateen]

I am working on Packet Tracer Toplogy where i have three routers on right where i configure static routig and i have three routers on left where ospf area 0 is configured. 

I redistribute static network into ospf with the command 

Router(config-router)#redistribute static subnets

i can see all the static routers loopbacks as OE2 network in OSPF routers but unfortuantely i am unable to ping on both sides as  there is no route available for OSPF in static network domain. 

I want to know how can i make mutual redistribution in order both network will be reachable. 

Thanks,

[Peter Paluch]

Abdul,

A static routing is static exactly because it does not learn anything on its own - rather, it depends on you to fully configure it. You cannot "redistribute into static".

What you can do is, for example, configure a static default route on R6 to point to R5, and on R5, configure another static default route to point to R4. It is a simplified way of making sure that for all destinations for which we do not have a better matching route, your routers in the static domain will send the packets toward the OSPF domain, hoping that the final destination is there. Or, you can meticulously configure a static route for each network located in the OSPF domain on your R6 and R5 - but notice that on R6, all those routes will point to R5, and on R5, they will all point to R4. That is why in your particular setup, the default route does the same thing, and is simpler to configure.

Please feel welcome to ask further!

Best regards,
Peter

[Abdul Mateen]

i add a default route on R5 and R6 pointed towards R4.
but i am still unable to ping OSPF domain network from R5 as shown in
figure

[Peter Paluch]

Abdul,

i add a default route on R5 and R6 pointed towards R4.

Let's clarify: On R6, the default route needs to point to R5's address on the R5/R6 link. On R5, the default route needs to point to R4's address on the R4/R5 link. Did you configure your static routing this way? If so, try performing a traceroute from R6 toward an IP address in the OSPF domain, and let us see how far you can get.

Best regards,
Peter

[Abdul Mateen]

Yes i do the same way...

I can ping R8(OSPF) from R6  but i cant ping R8 from R5 . Please check the attached the it could only trace to one hop. 

[Abdul Mateen]

Yes i do the same way...

I can ping R8(OSPF) from R6  but i cant ping R8 from R5 . Please check the attached the it could only trace to one hop. 

[Abdul Mateen]

I add the below command and R5 able to ping R8.

Router(config-router)#redistribute connected subnets

But the loopback of R4 which is advertise into OSPF is now seen as OE2 routes on R8 because of this command. 

How to overcome it?

[tellis002]

Hey Abdul,

That is correct behavior with the Loopback on R4 now advertising it as an external, E2 (which E2 is default over E1).  Following, that router is now a ASBR as well, advertising that loopback via a LSA type 5.  The metric will also default to 20 when redistributing.  

To get around this and to see the loopback in the OSPF topology as an intra-area route (LSA 2), you should advertise it into OSPF via the interface command or under the router ospf process.

Example:

int lo0

ip ospf 10 area 0

!

! OR

router ospf 10

network 30.30.30.30 0.0.0.0 area 0

!

However, the redistribution is still there and it appears you would like to keep for a specific reason.  At this point you can attach a route-map to the redistribution connected subnet command

Example:

ip prefix-list PRE_REDIS_OSPF permit 30.30.30.30/32

!

route-map REDIS_OSPF deny 10

match ip address prefix-list PRE_REDIS_OSPF

!

route-map REDIS_OSPF permit 20

!

router ospf 10

redistribute connected route-map REDIS_OSPF subnets

!

!

The only two possible issues you still may experience is:

1. the prefix-list i am using to match on your loopback, i am assuming it is a /32 subnet.  and/or

2. packet tracer might not be able to handle this depth of a configuration

Thanks and good luck - Tony Ellis