Figure 69 Redistributing a Vlsm Ospf Route into RIP

For example:

router rip network 131.108.0.0 redistribute static redistribute ospf 1 default-metric 1

ip route 131.108.10.0 255.255.255.0 nullO

Now that you have a route with the same mask as that of the Ethernet of R1, this static route is redistributed into RIPV1 across the Ethernet of R1. R1 advertises this route, and all the routers behind the Ethernet of R1 in the RIP domain will have connectivity to all the VLSM destinations behind the R1 -OSPF domain. This is not a solution to VLSM for RIP, however; it is merely one way to make RIP operable in a VLSM environment during migrations. (For further information on network migrations, see Chapter 12. "Migration Techniques." )

Now, we will discuss the configuration. The first command controls the RIP process; the second command tells RIP to run on all the connected interfaces of the local router that belong to network 131.108.0.0. The redistribute static command is used to send the static null route to accommodate the VLSM into the RIP domain. Next is the redistribute OSPF command, which redistributes the OSPF learned route with the same mask as the RIP route and routes from other major networks learned via OSPF. Finally, the default metric command is used for metric conversion between protocols because OSPF uses interface cost as its metric to a destination. Naturally, the destinations advertised by OSPF have a much higher metric than 15, so all the routes redistributed into RIP from OSPF will be considered infinity. To translate between metrics, you would use default metric command, which tells the RIP process that any routes redistributed into RIP via this router (R1, in this case) will have a hop count of one.

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