In the TCP/IP protocol suite, a Transport Layer (Layer 4) control protocol that operates on a hop-by-hop basis in order to signal quality of service (QoS) requirements for unicast and multicast data flows to each node and, thereby, reserve the necessary per-session resources from end-to-end across an Internet Protocol (IP) network. RSVP can operate in conjunction with other QoS protocols, including DiffServ and MPLS, to effect service discrimination. See also DiffServ, hop, IP, MPLS, multicast, node, protocol, protocol suite, QoS, session, TCP/IP, Transport Layer, and unicast.