Abstract: Multimedia applications are characterized by QoS (quality of service) requirements which depend on the quality of video and audio transmitted to the client, and the respect of time constraints associated to video and audio data. Much work has been done in order to provide system support that meets these requirements. However, existing proposals do not integrate the consequence of failure occurrence on QoS. In this paper, we address this issue by introducing a resource reservation model that integrates availability requirements. Our design goals for this model were:

• to allow programmers to reserve resources with respect to various QoS requirements including availability;
• to preserve the transparency of mechanisms used for availability;