The Resource Reservation Protocol (RSVP) represents one of the most important protocols used for resource reservation in the Internet. Developed initially by the Internet Engineering Task Force (IETF) to be used within the Integrated Services (IntServ) mechanism, this protocol undergoes over time several alterations. These alterations come either to respond to some applicability and functionality problems, or to extend the use of RSVP and to make it compatible with other mechanisms like Differentiated Services (DiffServ) or Multiprotocol Label Switching (MPLS). This work presents a survey on the evolution of RSVP illustrating the different alterations introduced over time for this protocol and explaining how each adaptation affects RSVP in ...