Buffer Space Tradeoffs in Multi-hop Networks

ABSTRACT We onsider the problem of bu er spa e allo ation in a multi-hop store-and-forward network and study the tradeo s between the amount of bu er spa e alloted to the endpoints of a virtual ir uit and that assigned to the ore nodes, i.e., routers. Simulation results hint at the possibility that the single-path paradigm of implementing networklayer virtual ir uits is fundamentally awed (rather than merely in onvenient from the viewpoint of bandwidth alloation and routing exibility). Despite its intuitive appeal (pa ket ordering, predi tability of end-to-end delays, et .), single-path forwarding neither results in eÆ ient utilization of available bu er spa e from the point of view of the entire network, nor does it provide the best overall performan e in terms of global bandwidth utilization and end-to-end quality of servi e. We demonstrate that the best quality of servi e for virtual ir uits (in terms of drop rate) is a hieved when 1. most of the bu er spa e in the network is at the destinations, and 2. a single virtual ir uit explores multiple paths, essentially following the general prin iples of de e tion routing.