This document describes a Quality of Service model (QOSM), for networks that support the use of the Controlled load service over a Diffserv cloud using pre-congestion notification. Ths is a technique to perform admission control in a Diffserv network by measuring the congestion level in a domain. New flows are admitted only if the current congestion level is below the allowed threshold. When the controlled load in a domain exceeds a certain threshold, the egress prompts the ingress to pre-empt certain flows. This proposal is based on the proposal made by B.Briscoe et al., for the extension of RSVP to support the Controlled load service over a Diffserv cloud using pre-congestion notification.