7.6 RIP and OSPF Redistribution
7.6.7 Setting up mutual redistribution
It is sometimes necessary to accommodate more complex network topologies such as independent RIP and OSPF clouds that must perform mutual redistribution. In this scenario, it is critically important to prevent potential routing loops by filtering routes. The router in the main figure is running both OSPF and RIP.

With the following commands, OSPF routes will be redistributed into RIP. You must specify the default metric to designate the cost of the redistributed route in RIP updates. All routes redistributed into RIP will have this default metric. (see Router#show running-config (1) command output).

It is a good practice to strictly control which routes are advertised when redistribution is configured. In the following example, a distribute-list out command causes RIP to ignore routes coming from the OSPF that originated from the RIP domain. (see Router#show running-config (2) command output).

Because it is common for OSPF and RIP to be used together, it is important to use the practices described here in order to provide functionality for both protocols on an internetwork. You can configure ASBRs that run both RIP and OSPF and redistribute RIP routes into the OSPF and vice versa. You can also create OSPF areas using ABRs that provide route summarizations. Use VLSM to conserve address space.