Topological Locality

Based on the hierarchical structure of the IP address space
Host addresses are grouped using a routing table
Addresses covered by the same route are `close'

Different routing tables are used for different granularities
Local tables with a default route group addresses by internal workgroup vs. external
Backbone default-free tables classify traffic globally
BGP AS paths can be used to group by ISP
Origin AS can be used to represent source or destination
NextHop AS will show traffic flow among a single ISP's peers