Some ASes currently use length-based filters to manage the size of the routing table they use and propagate. This draft explores an alternative to length-based filters which allows for more automatic configuration and which provides for better redundancy. Rather than use a filter, this draft proposes a method of modifying the BGP longest match algorithm by setting a bound on the prefix lengths eligible for preference. A bound would operate on long prefixes when covering route announcements are available; in certain circumstances it would cause a router to prefer an aggregate over a more specific route announcement.