+-----------------+
                             | MPLS base model |
                             +-----------------+
                           ____/  |  |_____  |________
                          /       |        \          \
                         /        |         \          \
                        o         o          o          +
                 +---------+  +---------+  +--------+ +-----------+ 
                 | RIB(v4) |  | RIB(v6) |  | RIB(x) | | RIB(mpls) |
                 +---------+  +---------+  +--------+ +-----------+

        +: created by the MPLS base model
        o: augmented by the MPLS base model