The Resource Reservation Protocol (RSVP) is a protocol for reserving bandwidth in IP networks. The RSVP protocol can be used to establish end-to-end connections over the IP protocol, using the same routers over which the data streams are transmitted.
The RSVP protocol first establishes a path over the routers by sending path messages periodically from the sender to the receiver. The path messages are used to explore, define and reserve the route for the RSVP messages. They are evaluated by RSVP-capable routers and reserve the appropriate bandwidth in the routers for subsequent transmission, which can be defined in terms of traffic classes and quality of service( QoS). The receiver confirms the reservation route. Once an RSVP route is defined and confirmed, the data packets with the user data are transmitted via the reserved route.
The RSVP protocol reservation procedure can also be used for voice quality compliance with Call Admission Control( CAC). The RSVP protocol, which is also used with IP multicast, was developed and standardized by the Internet Engineering Task Force( IETF) and Cisco and is described under RFC 2205.