Distributed multimedia applications require end-to-end quality of service(QoS) in order to be accepted and used. One approach to achieve end-to-end QoS is to provide end-to-end resource reservations. Resource ReSerVation Protocol (RSVP) [3] [1] is a unicast and multicast signalling protocol for setting up network bandwidth reservation. In this paper, we propose a solution for securing RSVP messages in a flexible, efficient and scalable manner. Our solution extends the RSVP protocol with a scalable QoS protection, using a hybrid hierarchical security approach. The RSVP messages go through two different protocol treatments - one within subnetworks and the other across subnetworks. We use delayed integrity checking within the subnetwork by sending feedback messages from the egress node. A stronger integrity and encryption check is made on messages sent across subnetworks. Our solution is thus an intermediate approach between the extremes of hop by hop authentication [2] and the SDS/CD protocols [5],and overcomes the drawbacks of the two protocols.