Tech Report NWU-EECS-06-15: On the Use of Parallel Connections in Web Browsers

8/6/2019 Tech Report NWU-EECS-06-15: On the Use of Parallel Connections in Web Browsers

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Electrical Engineering and Computer Science Department

Technical Report

NWU-EECS-06-15

October 16, 2006

On the Use of Parallel Connections in Web Browsers

David Choffnes, John Lange, Sam Rossoff, and Aleksandar Kuzmanovic

Abstract

Network measurements reveal that today's most popular web browsers open parallel

CP connections and use them to actively transfer data from web servers. This technique, base

n the assumption that ``more is better,'' is motivated by the need to improve user-perceived

erformance. While parallel connections indeed improve performance for lossless networks andwhen web pages are very large in size, we show, by means of analytical modeling, simulation,

nd testbed experiments, that no such improvements exist in scenarios that more closely

haracterize today's Internet. Moreover, we demonstrate that in addition to placing more stre

n web servers, the parallel TCP approach can degrade the web-response times to a level that

p to an order of magnitude below the level achievable by a single connection. We analyze the

oots of this phenomenon and find that the benefits of accelerated parallel download of small

bjects are largely overshadowed by the initial connection setup time, which dominates the

ntire transfer. We quantify the user-perceived latency and show that it dramatically

ncreases with the level of parallelism and congestion in the network.

Keywords: Web; parallel connections; TCP; HTTP; performance


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Tech Report NWU-EECS-06-15: On the Use of Parallel Connections in Web Browsers

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