kannan@oar.net (Kannan Varadhan) (10/31/90)
We are running OSPF with version 8.2 on our routers. I have a few questions on that score. Problem 1: A router has multiple static and other routes to various networks. How can one run OSPF on it and selectively import only required routes into OSPF? Note that the required routes will be/could be/are a subset of all the static routes on that router. Problem 2: A router with multiple interfaces to a local network is running OSPF. Each interface has a subnet address for the local network. Pictorially, this looks as | | | Each interface has addresses from 1| 2| 3| 131.183.0.0 subnet mask 255.255.255.0 +-----------+ running RIP. | OSPF RTR. | +-----------+ Likewise, interfaces 4, 5, 6 are on 4| 5| 6| 131.187.0.0, mask 255.255.255.0, running OSPF. The router is enables as a AS router, so that it can import RIP. The router insists on sending the routes for all of the subnets of 131.183.0.0 through the OSPF backbone area of 131.187.0.0. (well, we convincing it, but we didn't have any more magic cookies we could bribe it with). We tried defining the 131.183.0.0 as a range, belonging to area 0.0.0.1, but that didn't help at all. We are wondering if we have missed out anything. The OSPF documentation from Proteon says, "Outside of the area, a single route is advertised for each address range. To add an address to a given area, use the following command. This example would indicate that all subnets of the network 128.185.0.0 should belong to the area whose OSPF area ID is 128.185.0.0. OSPF Config> add range Area number [0.0.0.0]? 0.0.0.1 IP Address [0.0.0.0]? 128.185.0.0 IP Address mask [0.0.0.0]? 255.255.0.0". Our OSPF configuration looks as OSPF Config>lis all OSPF Protocol: Enabled # AS ext. routes: 256 Estimated # routers: 60 External comparison: Type 2 AS boundary capability: Enabled Import EGP routes: no Import RIP routes: yes Import static routes: yes Orig. default route: No Default route type: Type 2 Default route cost: 1 Area ID: 0.0.0.0 Authentication: 0 (None) Area ID: 0.0.0.1 Authentication: 0 (None) Address ranges: (131.183.0.0 , 255.255.0.0 ) OSPF interfaces: IP address Cost Rtrns TrnsDly Pri Hello Dead 131.187.40.6 10 5 1 1 10 60 131.187.48.6 1 5 1 1 10 60 Thanks, Kannan
jmoy@proteon.com (John Moy) (11/05/90)
Kannan- Here is an attempt to answer your P4200 OSPF questions: Problem 1: (Selectively import only certain static routes). The P4200 won't let you do this. What the P4200 does do is to separate the IP routing information into three broad categories (RIP-derived, EGP-derived and static/direct routes). Each category can then be imported (or not imported) into OSPF. For example, you can choose to import RIP routes, but not EGP or static routes. There are two places in the P4200's IP routing software where route filtering can be done on a per-network basis. The first is the EGP exchange tables (using this, you can set it up so that only certain EGP routes are imported into OSPF). The second is the "RIP-accept" filters, which define the set of routes that can be received by the P4200's RIP software (depending how your routing is set up, this may allow you to import only a subset of the RIP routes into OSPF). But neither of this features helps you much when importing static routes. In the P4200 implementation of OSPF version 2, we have separated the direct/static routes into two separate categories. So, you can now import directly attached routes, but not static routes. I don't know if this helps you any (and the version 2 code has not yet been released). Problem 2: (why are all these subnets being imported?) In release 8.2, you can condense all your subnets into a single network-level only when all the subnets belong to a single OSPF area. In your case, all the subnets of 128.183.0.0 don't really belong to an OSPF area, but instead are external (RIP-derived or direct) routes. So, if you configure the P4200 to import RIP and static/direct routes, each subnet will be imported as a separate OSPF (type 5 LSA) external route. There is a solution for this in the (again, unreleased) P4200 OSPF version 2 code. In that software, you can set a switch saying that you do not want to import any subnets as external routes. If this switch is enabled in your configuration, only a single route will be imported (destination 128.183.0.0, mask 255.255.0.0) for the entire subnetted network. John