Maintaining flow isolation in work-conserving flow aggregation

Abstract — In order to improve the scalability of scheduling protocols with bounded end-to-end delay, much effort has focused on reducing the amount of per-flow state at routers. One technique to reduce this state is flow aggregation, in which multiple individual flows are aggregated into a single aggregate flow. In addition to reducing per-flow state, flow aggregation has the advantage of a per-hop delay that is inversely proportional to the rate of the aggregate flow, while in the case of no aggregation, the per-hop delay is inversely proportional to the (smaller) rate of the individual flow. Flow aggregation in general is non-work-conserving. Recently, a work-conserving flow aggregation technique has been proposed. However, it has the disadvantage that the end-to-end delay of an individual flow is related to the burstiness of other flows sharing its aggregate flow. Here, we show how work-conserving flow aggregation may be performed without this drawback, that is, the end-to-end delay of an individual flow is independent of the burstiness of other flows. I

Stabilization of Max-Min Fair Networks without Per-Flow State

Let a flow be a sequence of packets sent from a source computer to a destination computer. Routers at the core of the Internet do not maintain any information about the flows that traverse them. This has allowed for great speeds at the routers, at the expense of providing only best-effort service. In this paper, we consider the problem of fairly allocating bandwidth to each flow. We assume some flows request a constant amount of bandwidth from the network. The bandwidth that remains is distributed fairly among the rest of the flows. The fairness sought after is max-min fairness, which assigns to each flow the largest possible bandwidth that avoids affecting other flows. The distinguishing factor to other approaches is that routers only maintain a constant amount of state, which is consistent with trends in the Internet (such as the proposed Differentiated Services Internet architecture). In addition, due to the need for high fault-tolerance in the Internet, we ensure our protocol is self-stabilizing, that is, it tolerates a wide variety of transient faults. Key words: networks stabilization, max-min fairness, quality of service, computer 1

Performance Evaluation of Load-Balanced Routing via Bounded Randomization

Future computer networks are expected to carry bursty traffic. Shortest-path routing protocols such as OSPF and RIP have t he disadvantage of causing bottlenecks due to their inherent single-path routing. That is, the uniformly selected shortest path between a source and a destination may become highly congested even when many other paths have low utilization. We propose a family of routing schemes that distribute data traffic over the whole network via bounded randomization; in this way, they remove bottlenecks and consequently improve network performance. For each data message to be sent from a source s to a destination d, each of the proposed routing protocols randomly choose an intermediate node e from a selected set of network nodes, and routes the data message along a shortest path from s to e. Then, it routes the data message via a shortest path from e to d. Intuitively, we would expect that this increase the effective bandwidth between each source-destination pair. Our simulation results indicate that the family of proposed load-balanced routing protocols distribute traffic evenly over the whole network and, in consequence, increases network performance with respect to throughput, message loss, message delay and link utilization. Moreover, implementing our scheme requires only a simple extension to any shortest-path routing protocol