Re: Why can download manager can help?

From: Jon Mansey ([email protected])
Date: Thu May 31 2001 - 12:21:34 EDT

  • Next message: Mike Jagdis: "Re: Why can download manager can help?"

    This is especially relevant to satellite IP networks where the
    latency affects each TCP connection by limiting the maximum
    throughput to an un-modified TCP stack on a client.

    Opening multiple parallel TCP connections is a way "pull" more
    bandwidth on "one session".

    You're right though, it probably wouldnt improve things over low
    latency 56k or T1 lines.

    jm

    >?Some download managers such as NetAnts claim to be designed to maximize
    >throughput by making multiple HTTP connections, each of which downloads
    >a separate part of a single big file.
    >
    >I wonder why doing this is helpful.
    >
    >Suppose a user connects to the Internet via a 56kbps line. His first
    >HTTP connection should consume all the bandwidth of his line, how can
    >the multiple simultanous connections help?
    >
    >Assume the Web server haven't limited the transfer rate for the requests
    >to it. If the user had a 1.5Mbps line now, then his first HTTP
    >connection could still transfer the file at 1.5Mbps (assume the network
    >is not the bottleneck), how can the multiple connections help?
    >
    >Now suppose the network is the performance bottleneck (maybe network
    >congestion), then no matter how many simultanous connections are used,
    >the overall transfer speed is limited by the network. How can the
    >multiple connections help?
    >
    >However, by real experience, this kind of download manager is helpful
    >and reduce the overall respond time. Why? Is it related to the HTTP 1.1?
    >
    >Thank you for your attention.
    >
    >Angus Wong



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