There are two fundamental changes which must be applied to Inter- Domain routing protocols in order for this plan to work. First, the concept of network "class" needs to be deprecated - this plan assumes that routing destinations are represented by network and mask pairs and that routing is done on a longest-match basis (i.e., for a given destination which matches multiple network+mask pairs, the match with the longest mask is used). Second, current inter-domain protocols generally do not support the concept of route aggregation, so the new semantics need to be implemented in a new set of inter-domain protocols. In particular, when doing aggregation, dealing with multi-homed sites or destinations which change service providers is difficult. Fortunately, it is possible to define several fairly simple rules for dealing with such cases.