Because he was uploading a file, his computer was sending the modem as many upstream packets as it could handle. And the modem was pretending to handle a lot more than it actually could, turning none away while building up a massive queue. So when Gettys tried to download something at the same time—to visit a webpage or check email—his ACK packets would get stuck behind the upload, having to wait in line at the modem to leave the house. Because his ACKs then took forever to return to the web and email servers, the servers would in turn throttle their own downstream connection speeds to a
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