Leland+Wilson_INFOCOM_91 - High Time-Resolution Measurement...

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High Time-Resolution Measurement and Analysis of LAN Traffic: Implications for LAN Interconnection Will E. Leland Daniel V. Wilson Bellcore 445 South Street Morristown, NJ 07960 Abstract The interconnection of local area networks is increasingly important, but little data are available on the characteristics of the aggregate traffic that LANs will be submitting to the interconnection media. In order to understand the interactions between LANs and the proposed interconnection networks (MANs, WANs, and BISDN networks), it is necessary to study the behavior of this external LAN traffic over many time scales – from milliseconds to hundreds of seconds. We present a high time-resolution hardware monitor for Ethernet LANs that avoids the shortcomings of previous monitoring tools, such as traffic burst clipping and timestamp jitter. Using data recorded by our monitor for several hundred million Ethernet packets, we present an overview of the short-range time correlations in external LAN traffic. Our analysis shows that LAN traffic is extremely bursty across time domains spanning six orders of magnitude. We compare this behavior with simple formal traffic models and employ the data in a trace-driven simulation of the LAN-BISDN interface proposed for the SMDS SM service. Our results suggest that the pronounced short-term traffic correlations, together with the extensive time regime of traffic burstiness, strongly influence the patterns of loss and delay induced by LAN interconnection. 1. Introduction As the interconnection of local area networks becomes increasingly important, understanding the interactions between LAN traffic and larger area (MAN, WAN, and BISDN) networks becomes ever more critical. Because the detailed behavior of LAN traffic greatly influences both the performance and the design of potential LAN interconnection schemes, we need to understand and realistically model LAN traffic over a very wide range of time scales: from milliseconds to days. Unfortunately, existing tools for measuring LAN traffic cannot accurately resolve short time scales, and existing approaches to analyzing LAN traffic do not provide adequate information over such disparate time domains. In this paper, we describe a novel hardware monitor for Ethernet traffic, characterize its accuracy, and present some analysis perspectives for understanding and characterizing the resulting traffic measurements. We then illustrate the importance of realistic traffic characterization with an example drawn from a simulation study of the packet loss and delay effects induced by one LAN-to-BISDN access proposal. Although there have been many studies of LAN traffic since the early Ethernet measurements of Shoch and Hupp, [1] the emphasis has been on intermediate time scale behavior [2] [3] [4] or on user-oriented measures of behavior such as LAN throughput and delay [5] [6] . More seriously for our study, little published data are available on the packet loss and timestamp errors introduced by the data collection techniques employed. The early studies typically used time
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This note was uploaded on 09/13/2009 for the course EE 6345 taught by Professor Cantrell during the Spring '09 term at University of Texas at Dallas, Richardson.

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Leland+Wilson_INFOCOM_91 - High Time-Resolution Measurement...

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