redistribute ospf intra-area routes only

[cparish17]

I need to identify intra-routes and redistribute them into another routing protocol. "Show Ip route" clear distinguishes between Inter-area (IA) and intra-area (O) routes. I can't find anything in a route-map to identify them. The OSPF "distance" command can also tell the difference... so why can't I find a way in a route -map to tell them apart?

I have to be overlooking something.

[Reza Sharifi]

You can use a prefix-list to match

ip prefix-list test permit <ip range>

route-map test permit 10

match ip address prefix-list test

router eigrp 20

red os x route-map test

eigrp is an example

HTH 

[cparish17]

Yeah... I know that would work, but I'm trying to avoid that. It would be tedious to identify all the prefixes, they're not summarizable for the most part, and would require change everytime you added or removed a subnet from the area. That's just not very scaleable... particularly as the area is geographically dispursed (connected by radio backbone) and different groups might be making changes without effective communications.

Intra-area vs. Inter-area just seems like an easily identifiable characteristic that the routes have in common, and it doesn't make sense that there's no way to match that in a route-map. I mean, you can match ospf external type  1 vs ospf external type 2.... why not inter-area vs. intra-area. I think if you could just math LSA type, you could filter out lsa type 3's.

[Jon Marshall]

Unfortunately route maps with redistribution can only match internal routes but can't distinguish between them.

The only suggestion I can think of is that within a route map you can match on the route source and your network summary LSAs will all have the route source as the ABR for that area. So you can match on the route source and filter out those routes and then allow all other routes assuming you only redistribute internal routes.

The only problem is that the ABR will also have LSAs for that area so you need to allow those with an acl or prefix list, deny the other routes with a source of the ABR (network summary LSAs) and than allow all other internal routes.

The advantage if it works is that you would not need to modify anything when adding another subnet etc.

I did a quick lab to test the theory without the acl or prefix list bit and it worked so it may be an option to consider but you would obviously need to test it yourself before implementing if you decided to try it.

Jon

[cparish17]

Great idea.. .thanks.