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Integrated Services, or Int-Serv, is a model for providing QoS on the Internet and intranets by using bandwidth reservation techniques. As originally designed, the Internet supports only best-effort delivery of data packets across multiaccess (shared) network links. There is little support for QoS (quality of service) due to the packet-oriented nature of the Internet and factors such as variable queuing delays and congestion losses.

The Int-Serv model defines methods for identifying traffic flows, which are streams of packets going to the same destination. An Internet voice call is an example. The Int-Serv concept reserves just the right amount of bandwidth to support the flow's requirements and protect it from disruptions caused by network congestion. Reservations are negotiated with each network device along a route to a destination. If each device has resources to support the flow, a reserved path is set up. RSVP (Resource Reservation Protocol) is the signaling protocol that sends messages in the forward direction to request reservations, and then sends messages in the reverse direction to set up the reservations if all devices in a route agree to reserve resources.