PIT of B      PIT Extension          PIT of C      PIT Extension
+--------+------++------+------+     +--------+------++------+------+
| Prefix | Face || HIDi | HIDo |     | Prefix | Face || HIDi | HIDo |
+========+======++======+======+     +========+======++======+======+
|  /p0   | F_A  || h_A  | h_B  |     |  /p0   | F_A  || h_A  |      |
+--------+------++------+------+     +--------+------++------+------+
                    |       ^                            |
               send |       '----------------------, ,---' send
                    v                 match        | v
,---,              h_A          ,---,              h_B          ,---,
| A | <------------------------ | B | <------------------------ | C |
'---'                           '---'                           '---'