+----------+   P3[AS5 AS1]  +------------+
                 | AS4(ISP4)|<---------------|  AS5(ISP5) |
                 +----------+      (P2P)     +------------+
                     /\   /\                        /\
                     /     \                        /
         P1[AS2 AS1]/       \P2[AS3 AS1]           /
              (C2P)/         \(C2P)               /
                  /           \                  /
           +----------+    +----------+         /
           | AS2(ISP2)|    | AS3(ISP3)|        /
           +----------+    +----------+       /
                    /\           /\          /
                     \           /          /
               P1[AS1]\         /P2[AS1]   /P3[AS1]
                  (C2P)\       /(C2P)     /(C2P)
                        \     /          /
                     +----------------+ /
                     |  AS1(customer) |/
                     +----------------+
                          P1, P2, P3 (prefixes originated)

         Consider that data packets (sourced from AS1)
         may be received at AS4 with a source address
         in P1, P2, or P3 via any of the neighbors (AS2, AS3, AS5):
         * Feasible-path uRPF fails
         * Loose uRPF works (but not desirable)
         * Enhanced feasible-path uRPF works best