The Resource Reservation Protocol (RSVP) is a Transport Layer protocol designed to reserve resources across a network for an integrated services Internet. RSVP operates over an IPv4 or IPv6 Internet Layer and provides receiver-initiated setup of resource reservations for multicast or unicast data flows with scaling and robustness.

RSVP can be used by either hosts or routers to request or deliver specific levels of quality of service (QoS) for application data streams or flows. RSVP is not a routing protocol and was designed to interoperate with current and future routing protocols. RSVP-TE, the traffic engineering extension of RSVP, is becoming more widely accepted nowadays in many QoS-oriented networks.

The main attributes of RSVP are:

  • RSVP requests resources for simplex flows: a traffic stream in only one direction from sender to one or more receivers.
  • RSVP is not a routing protocol but works with current and future routing protocols.
  • RSVP is receiver oriented: in that the receiver of a data flow initiates and maintains the resource reservation for that flow.
  • RSVP maintains “soft state” of the host and routers’ resource reservations, hence supporting dynamic automatic adaptation to network changes.
  • RSVP provides several reservation styles and allows for future styles to be added to protocol revisions to fit varied applications.
  • RSVP transports and maintains traffic and policy control parameters that are opaque to RSVP.