2

I recently downloaded XCode. The file size is 1.7 GB. In Activity Monitor, it indicated while downloading, that my upload speed was basically 50% of my download speed for the entire duration of the download. After the download was complete, the 'Data received' in Activity Monitor read 1.7 GB and the 'Date sent' read just under 1 GB (numbers are approximate). I wasn't doing anything else that would involve network usage. This isn't the first time that I've seen this pattern.

It seems to apply when using ethernet or Wi-Fi. If it makes a difference, I'm running Lion on a MBP, connecting through ethernet, and downloading with App Store. Below is a screen shot from Activity Monitor taken during a previous download.

What is being uploaded and why is it always approximately 50% of the download? Does this pattern apply to all data transmission?

Activity Monitor screen shot

Improve this question
6
  • What app are you using to download?
    – Paul
    Nov 21, 2011 at 23:57
  • I'm using App Store to download it. But the same pattern applies when I use a web browser.
    – mockman
    Nov 21, 2011 at 23:58
  • 3
    The only packets sent in return for an http GET would be ACKs, which of a file that size would be less than 1% compared to downloaded. If you are reading the numbers right, then I would get wireshark out and take a look.
    – Paul
    Nov 22, 2011 at 0:03
  • 1
    Do both lines (sent/sec and recieved/sec) drop to zero once the download has completed?
    – Paul
    Nov 22, 2011 at 0:18
  • Yes. They move in lock-step.
    – mockman
    Nov 24, 2011 at 19:20

1 Answer 1

Reset to default
0

Bad connection quality and re-transfer requests and re-transfers for TCP-packets probably.

Checked rather easy: try any other download from nearest (in net, not geo, sense) location

Improve this answer
2
  • I just downloaded iTunes using a web browser (Omniweb). The same pattern occurred. How can I find a nearby download to test? And by the way, if the connection were bad, would I be able to get 20 MB/s speeds?
    – mockman
    Nov 24, 2011 at 19:43
  • While a bad connection would result in retransmission of data, the downloaded quantity would increase at a far greater rate than the uploads. A TCP ACK is tiny, as is an entire HTTP request for the 1.7GB to be sent again - less than 1KB. As the download took 1.7GB for a 1.7GB file and the speeds are healthy, this does not account at all for the upload.
    – Paul
    Nov 24, 2011 at 20:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.