Reservations for aggregate traffic: experiences from an RSVP tunnels implementation

Abstract

Among its various uses, IP-in-IP (Internet Protocol) tunneling is a simple way to aggregate the data flows from multiple sources to multiple destinations into one flow, to cross part of the Internet. In this paper, we report our design and implementation of RSVP (Resource ReSerVation Protocol) support for resource reservations over IP-in-IP tunnels, and our experience from this effort that revealed a number of issues related to making resource reservations for aggregate data flows. First, aggregation and de-aggregation go in pairs; thus, the exit point of the tunnel must have adequate information to be able to de-multiplex the aggregate tunnel reservation back to reservations for individual flows. Second, if multiple reserved sessions exist over one tunnel, the two tunnel end-points need mechanisms to synchronize on which end-to-end reservation is bound to which tunnel reservation. On the other hand, mapping all reservations of the same traffic class into one tunnel session can substantially simplify the protocol. Furthermore, one must also properly map error reports from the aggregate reservation back to the ends of individual flows.