RIP is a is an interior gateway protocol that was often used in interior networks and in some degree in internet networks. It helps the router adapt to the modifications that are made in a network regarding connections. Now it become less used since more efficient protocols were implemented like OSPF or IS-IS. It is limited to a lower number of routers, a maximum of fifteen router.
In the mesh topology, each computer is connected to the other with a separate physical link in a network. It is most reliable topology as the network does not get down in case one of the nodes is failed.