The notion of end-to-end capacity and its application to the estimation of end-to-end network delays (original) (raw)

An approximation of the end-to-end delay distribution

2003

In this paper we propose an approximation for the end-to-end (queueing) delay distribution based on endpoint measurements. We develop a notion of the end-to-end capacity which is defined for a path of interest. We show that the end-to-end path can be represented by a single-node model with the end-to-end capacity in the sense that the single-node model is equivalent to the original path in terms of the queue-length and the departure.

A Simulation Study of the Measurement of Queueing Delay over End-to-End Paths

IEEE Open Journal of the Computer Society, 2020

Determining the qualitative states of the Internet requires an accurate knowledge of queueing delay over an end-to-end path. However, the measurement of queueing delay in a large network is still considered a complex and open problem. Existing schemes that measure queueing delay compensate for this complexity using a high infrastructural support and administrative access to the path under test even though their feasibility and accuracy on the Internet are low. In this paper, we propose an active scheme, called COMPRESS: COMpound Probe compRESSion, to measure queueing delay on all routers over an end-to-end path. The proposed scheme performs per-hop measurement using UDP-based probing packets. It is both simple and self-sufficient in comparison to the existing schemes. We have implemented the proposed scheme in a simulation environment to present a controlled performance evaluation under different levels (e.g., light, moderate, and heavy) and types (e.g., symmetric and asymmetric) of queueing delays over single-and multiple-hop paths. Our simulation results show that the scheme is sensitive to the induced queueing delays and consistently provides a high measurement accuracy. Overall, the scheme has an average measurement error of around 20% or below over the simulated paths.

End-to-end queuing delay assessment in multi-service ip networks

Journal of Statistical Computation and Simulation, 2002

Packet-based networks are more and more used to transport interactive streaming services like telephony and videophony. To guarantee a good quality for these services, the queuing delay and delay jitter introduced in the transport of voice or video flows over the packet-based network should be kept under control. Because data sources tend to increase their sending rate until (a part of) the network is congested, mixing real-time traffic and data traffic in one queue would lead to unacceptable high delays for real-time services. Therefore, voice and video packets need to get preferential treatment (e.g. head-of-line priority) over data packets in the network nodes. Therefore, the queuing behavior of the voice and video packets can be studied more or less independently from the traffic generated by data services. Simple methods to assess the end-to-end delay are primordial. Since it is well known that an aggregate of voice (and CBR video) sources is accurately modeled by a Poisson arrival process and that delays in consecutive nodes are more or less statistically independent, this boils down to developing methods to calculate quantiles of the total queuing delay through a system of N statistically independent M/G/1 nodes. This paper develops four methods to calculate quantiles of the total queuing delay: a Gaussian method, a method based on the numerical inversion of the moment generating function of the total queuing delay developed by Abate & Whitt and two methods based on the assumption that the tail distribution of the individual queuing delay of one node is approximately exponential. The Gaussian method is the simplest, but only gives crude results. The method of Abate & Whitt is the most complex and breaks down for large quantiles. The methods based on the assumption of an exponential tail produce results that are more or less equally accurate as long as there is a node where the load is high enough.

Network Characteristics: Modelling, Measurements, and Admission Control

Quality of Service—IWQoS 2003, 2003

Round trip delays constitute the basic network measure that can be obtained by end systems without any network support. Our aim is to design measurement-based admission control strategies for streaming applications based on such minimal feedback on network state. To this end we discuss simple statistical models of packet round trip delays accross either local or wide area networks. We observe that the delay component due to queueing scales like the reciprocal of the spare capacity, at least in a 'heavy traffic' regime where spare capacity is scarce. Our models also allow to capture the correlations between consecutive measurements. Based on these results we propose a two-stage strategy for inferring spare capacity along a network path. We show consistency of this estimate, and analyse its asymptotic variance when the number of samples becomes large. We have experimented these strategies in a local network environment. We observe a good match between theory and practice for switched Ethernets. Surprisingly, the match deteriorates only slightly when the network path comprises hubs, although the theoretical models seem to be less applicable to such technology.

Analysis of Point-To-Point Packet Delay In an Operational Network

2004

In this paper we perform a detailed analysis of point-to-point packet delay in an operational tier-1 network. The point-to-point delay is the time experienced by a packet from an ingress to an egress point in an ISP, and it provides the most basic information regarding the delay performance of the ISP's network. Using packet traces captured in the operational network, we obtain precise point-to-point packet delay measurements and analyze the various factors affecting them. Through a simple, step-by-step, systematic methodology and careful data analysis, we identify the major network factors that contribute to point-to-point packet delay and characterize their effect on the network delay performance. Our findings are: 1) delay distributions vary greatly in shape, depending on the path and link utilization; 2) after constant factors dependent only on the path and packet size are removed, the 99th percentile variable delay remains under 1 ms over several hops and under link utilization below 90% on a bottleneck; 3) a very small number of packets experience very large delay in short bursts. (Baek-Young Choi). extension of [7] to the multiple hops case. The pointto-point delay measures the one-way delay experienced by packets from an ingress point to an egress point across an ISP's network and provides the most basic information regarding the delay performance of the ISP's network . The objective of our study is two-fold: 1) to analyze and characterize the pointto-point packet delays in an operational network; and 2) to understand the various factors that contribute to point-to-point delays and examining the effect they have on the network delay performance.

Resequencing delays under multipath routing-asymptotics in a simple queueing model

INFOCOM 2006. 25th IEEE …, 2006

We study the resequencing delay caused by multipath routing. We use a queueing model which consists of parallel queues to model the network routing behavior. We define a new metric, denoted by γ, to study the impact of resequencing on the customer end-to-end delay. Our results characterize some properties of γ with respect to different service time distributions. In particular, the resequencing delay can be negligible when the delay along each path is light-tailed, but can be of major concern when it is heavy-tailed.

Modeling, simulation and measurements of queuing delay under long-tail internet traffic

ACM SIGMETRICS Performance Evaluation Review, 2003

In this paper we describe an analytical approach for estimating the queuing delay distribution on an Internet link carrying realistic TCP traffic, such as that produced by a large number of finite-size connections transferring files whose sizes are taken from a long-tail distribution. The analytical predictions are validated against detailed simulation experiments and real network measurements. Despite its simplicity, our model proves to be accurate and robust under a variety of operating conditions, and offers novel insights into the impact on the network of long-tail flow length distributions. Our contribution is a performance evaluation methodology that could be usefully employed in network dimensioning and engineering.

Calculating End-to-End Queuing Delay for Real-Time Services on an IP Network

Lecture Notes in Computer Science, 2003

A crucial factor for real-time (interactive) services is the end-to-end delay experienced by the application. The contribution resulting from the queuing delay induced by the network nodes is the most difficult to assess. First, it is a stochastic quantity which should be aggregated over many (possibly different) network nodes. Secondly, the queuing delay in a single node stems from two different mechanisms: one related to interference with other interactive flows and one related to interference with the ubiquitous best-effort data flows. Earlier work assessed these two components separately, leading to a 'worst case' result. This paper models both components and develops formulas to calculate exact results for the end-to-end queuing delay. Results are shown indicating an improvement up to 45% over the worst-case method. The formulae developed in this paper are expected to be useful in network dimensioning, in setting network performance requirements and in admission control mechanisms.

A minimum-delay-difference method for mitigating cross-traffic impact on capacity measurement

Proceedings of the 5th …, 2009

The accuracy and speed of path capacity measurement could be seriously affected by the presence of cross traffic on the path. In this paper, we propose a new cross-traffic filtering method called minimum delay difference (MDDIF). Unlike the classic packet-pair dispersion techniques, the MDDIF method can obtain accurate capacity estimate from the minimal possible delay of packets from different packet pairs. We have proved that the MDDIF method is correct and that it takes less time to obtain accurate samples than the minimum delay sum (MDSUM) method. We also present analytical and measurement results to evaluate the MDDIF method and to compare its performance with the MDSUM method.