A new proposal for RSVP refreshes

As a soft-state protocol, RSVP specifies that each RSVP node sends periodic control messages to maintain the state for active RSVP sessions. The protocol overhead due to such periodic messages grows linearly with the number of RSVP sessions. One may reduce the overhead by using a longer refresh period, which unfortunately leads to longer delays in re-synchronizing RSVP state. In this paper we introduce a novel "state-compression" approach to reducing the overhead of periodic refreshes. Instead of per session refresh messages, an RSVP node sends periodically to each of its neighbor node a digest message that contains a compressed version of the entire RSVP state shared with that particular neighbor. In order to speed up state synchronization in face of message losses we also enhance RSVP with an acknowledgment mechanism. Our mechanisms achieve a constant message transmission overhead and low delay while retaining the soft-state nature of the RSVP protocol.