LIRA: An Approach for Service Differentiation in the Internet

In this paper, we study the Assured Service model proposed by Clark and Wroclawski [3, 4]. While existing schemes use service profiles that are defined in terms of absolute bandwidth, it is difficult, if not impossible, to design provisioning algorithms that achieve simultaneously good service quality and high resource utilization for such services with large spatial granularities. We propose an Assured Service model, called LIRA (Location Independent Resource Accounting), in which service profiles are defined in units of resource tokens, rather than absolute bandwidth. The number of resource tokens charged for each in-profile packet is a dynamic function of the path it traverses and the congestion level. Defining service profile in terms of resource tokens allows more dynamic and flexible network control algorithms that can simultaneously achieve high utilization and ensure high probability delivery of in-profile packets. We present an integrated set of algorithms that implement the model. Specifically, we leverage the existing routing infrastructure to distribute the path costs to all edge nodes. Since the path cost reflects the congestion level along the path, we use this cost to design dynamic routing and load balancing algorithms. To avoid packet re-ordering within a flow, we devise a lightweight mechanism that binds a flow to a route so that all packets from the flow will traverse the same route. To reduce route oscillation, we probabilistically bind a flow to one of the multiple routes. Simulation results are presented to demonstrate the effectiveness of the approach. This research was sponsored by DARPA under contract numbers N66001-96-C-8528 and N00174-96-K-0002, and by a NSF Career Award under grant number NCR-9624979. Additional support was provided by Intel Corp., MCI, and Sun Microsystems. Views and conclusions contained in this document are those of the authors and should no be interpreted as representing the official policies, either expressed or implied, of DARPA, NSF, Intel, MCI, Sun, or the U.S. government.