YESSIR: A Simple Reservation Mechanism for the Internet

RSVP has been designed to support resource reservation in the Internet. However, it has two major problems: complexity and scalability. The former results in heavy message processing overhead at end systems and routers, and inefficient firewall processing at the edge of the network. The latter implies that in a backbone environment, the amount of bandwidth consumed by refresh messages and the storage space that is needed to support a large number of flows at a router are too large. We have developed a new reservation mechanism that simplifies the process of establishing reserved flows while preserving many unique features introduced in RSVP. Simplicity is measured in terms of control message processing, data packet processing, and user-level flexibility. Features such as robustness, advertising network service availability and resource sharing among multiple senders are also supported in the proposal. The proposed mechanism, YESSIR (YEt another Sender Session Internet Reservations) generates reservation requests by senders to reduce the processing overhead, builds on top of RTCP, uses \emph{soft state} to maintain reservation states, supports shared reservation and associated flow merging and is backward compatible with the IETF Integrated Services models. YESSIR extends the all-or-nothing reservation model to support partial reservations that improve over the duration of the session. To address the scalability issue, we investigate the possibility of using YESSIR for per-stream reservation and RSVP for aggregate reservation.