What is sub-optimal routing and what tool is best to manage sub-optimal routing?

suboptimal routing : Creates routing hole

Eg: when you are redistributing between two routing protocol eg. OSPF/EIGRP, if you dont configure filters or administrative distance modification then suboptimal routing may occurs. One of the routing protocol (eigrp) advertize a route to the other routing protocol (ospf) with a better AD even this route is originaly in the other routing domain (ospf), so in a scenario like this without filter or manipulations of AD would be create a routing loop.