7.5 Using Multiple Routing Protocols
7.5.6 Modifying administrative distance (optional)
In some cases, you will find that a router will select a suboptimal path because it believes a routing protocol that, although it has a better administrative distance, has a poorer route. One way to make sure routes from the desired routing protocol are selected is to give the undesired routing protocol a larger administrative distance. Perform the following steps:
  1. Create an access list of the networks to be redistributed.
  2. Access the appropriate routing process.
  3. Assign the access list to the distance command.

router(config-router)#distance weight [address mask [access-list-number | name]] 

Use this command only after routing loops are detected, or if you have done significant planning and really understand how packets are forwarded in the existing network.