ABE: providing a low-delay service within best effort

Abstract

e present an enhancement to the IP best effort service, alternative best effort (ABE), which relies on the idea of providing low delay at the expense of maybe less throughput. The motivation for such a service is twofold. First, there now exist interactive multimedia applications that perform well across a wide range of loss and throughput conditions [1,2], but for which delay often remains the major impediment [3]. Second, unlike differentiated services, we would like to design a service where it is not required to police how much traffic uses the low delay capability, in order to retain the operational simplicity of a single-class network.The article is organized as follows. We define the ABE service and analyze its implications. In particular, we identify and discuss the central issue, called green does not hurt blue. We also discuss migration issues from the traditional IP service (flat best effort) to ABE. As a proof of concept, a router implementation is described; it is based on the combination of a scheduler called duplicate scheduling with deadlines (DSD) and a traditional control loop. Implementations were done in the Linux kernel, in the Dummynet network emulator, and in the ns-2 simulator [4]. Simulation results of the ns-2 implementation are shown. We review related work and position ABE with respect to other proposals in differentiated services. The ABE Service Definition of the ServiceABE is defined as follows:• ABE packets are marked either green or blue. 1 • Green packets receive a low bounded delay at every hop.Realistic values of the per-hop delay bound are discussed later in this section.• Green does not hurt blue: If some source decides to mark some of its packets green rather than blue, the quality of the service(delay and throughput) received by sources that mark all their packets blue remains the same or becomes better. This definition is made more specific later.• All ABE packets belong to one single best effort class. If the total load is high, every source may receive little throughput. However, entirely blue sources experience more throughput than entirely green sources sharing the same network resources. AbstractWe propose alternative best effort (ABE), a novel service for IP networks, which relies on the idea of providing low delay at the expense of maybe less throughput. The objective is to retain the simplicity of the original Internet single-class best-effort service while providing low delay to interactive adaptive applications. With ABE, every best effort packet is marked as either green or blue. Green packets are guaranteed a low bounded delay in every router. In exchange, green packets are more likely to be dropped (or marked using congestion notification) during periods of congestion than blue packets. For every packet, the choice of color is made by the application based on the nature of its traffic and on global traffic conditions. Typically, an interactive application with real-time deadlines, such as audio, will mark most of its packets as green, as long as the network ...

Theories and models for Internet quality of service

“…A simpler service alternative is proposed by Hurley et al under the name Alternative Best Effort (ABE) [140] or by Guo et al under the name Best Effort Differentiated Service (BEDS) [124]. Both propose to associate a priority for delay with a negative priority for throughput (or loss).…”

Transform-Domain Analysis of Packet Delay in Network Nodes with QoS-Aware Scheduling

“…Together with the fact that the MR systems with N and N − 1 reservations also hold the same total number of packets, theorem (26) leads to the following corollary concerning the joint pgfs of the system state of both systems. Let P [N ] k be the system state distribution (15) for a system with N reserved spaces.…”

“…A controllable DiffServ mechanism is Proportional Differentiated Services [18], which aims to quantitatively differentiate the QoS among the classes relative to some predefined parameters. Many other scheduling mechanisms that limit the delay of a selected flow keep track of a 'deadline' for each queued packet, such as earliest deadline first (EDF) [43,38] and alternative best-effort [26] or use virtual clocks [52]. An overview can be found in [25,40].…”

Quality of service and denial of service

“…Examples of non-elevated priority services include the Alternative Best Effort service [3], which lets users trade off delay against loss, and scavenger-like services [6], which allow users to take advantage of otherwise unused network capacity in a way that does not affect the performance of the default best-effort service.…”