dual AS graph features


AS hop count = #sessions in a path
easy to compare with AS hops
If necessary, add: 0-AS & AS-0 for traffic origination/termination
adds rigidity to the graph
constrain path by continuity and direction
like differential equation, but more choice at each step
path continuation non-unique

general case:
        nodes: AS n-tuples, links: n+1-tuples