How to disable automatic route redistribution in OSPF

[joyride_us]

Hi,

I have routers running several OSPF processes each and they seem to redistribute those routes to each other by default.

How can I block this and have totally independant processes?

Thank you

[Kevin Dorrell]

Normally the OSPF processes will not redistribute routes to each other except inasmuch as they share common networks. Unless, of course, you specifically tell it to do so.

So why could they appear to be redistributing? If you have two OSPF processes in the box that are both listening to the same interface, then they will both pick up the routing updates from that interface.

Don't forget that the process number of the OSPF only has local significance within the box. It is not like an AS number in EIGRP. If you want to distinguish the routing updates on a single interface for two different processes, they I guess you could do it by setting them up as two different areas. The area attribute does have significance outside the box.

I have never tried using more than one OSPF process in the box, and if I did, I would be careful not to let them share the same area on the same interface. It sounds confusing, and I think it will need some careful design work to sort it out.

Kevin Dorrell

Luxembourg

[Richard Burts]

The last time I tested it you could NOT get two OSPF processes active on the same interface at the same time. I doubt that this behavior has changed.

I agree with Kevin that redistribution between OSPF processes is not automatic. What are you seeing that leads you to think that they are redistributing? On the router that has multiple processes, all of the OSPF routes do show up in the routing table (and there is nothing in the routing table that distinguished which OSPF process produced the route). But OSPF does not advertise out of the routing table it advertises out of the link state data base and in the data base there is certainly indicators of which process produced the information.

HTH

Rick

[Kevin Dorrell]

OK Rick - about the two OSPF processes on the same interface - I concede to your greater experience. I'm working mainly from theory, as I don't use OSPF every day. But I will check it out next time I book a lab. Gives me a good excuse to do the OSPF chapters from "Practical Studies" again.

I thought about the wording of my posting. Of course I should not have said they "receive updates from the same interface", but rather "form adjacencies through the same interface". But they won't, from what you say.

We really need to see the result of all the show ip ospf commands.

Kevin Dorrell

Luxembourg